PONTIFÍCIA UNIVERSIDADE CATÓLICA DE MINAS ...RESUMO O aparelho Herbst (AH) é um dos dispositivos mais utilizados como opção terapêutica no tratamento das más oclusões de Classe

PONTIFÍCIA UNIVERSIDADE CATÓLICA DE MINAS GERAIS

Programa de Pós-graduação em Odontologia

Paula Loureiro Cheib Vilefort

AVALIAÇÃO TRIDIMENSIONAL DAS MUDANÇAS DENTOESQUELÉTICAS

APÓS TERAPIA COM O APARELHO HERBST EM DIFERENTES ESTÁGIOS DE

MATURAÇÃO ESQUELÉTICA: um estudo multicêntrico

Belo Horizonte

2018





Tese apresentada ao Programa de Pós-graduação em

Odontologia da Pontifícia Universidade Católica de

Minas Gerais, como requisito parcial para a

obtenção do título de Doutor em Odontologia, Área

de Concentração: Clínicas Odontológicas.

Linha de Pesquisa: Métodos de Diagnóstico por

Imagem, Radiobiologia e Radioproteção.

Orientador: Prof. Dr. Bernardo Quiroga Souki

Coorientadora: Profa. Dra. Lucia Helena Soares

Cevidanes

Belo Horizonte

2018

FICHA CATALOGRÁFICA

Elaborada pela Biblioteca da Pontifícia Universidade Católica de Minas Gerais

Vilefort, Paula Loureiro Cheib

V699a Avaliação tridimensional das mudanças dentoesqueléticas após terapia com

o aparelho herbst em diferentes estágios de maturação esquelética: um estudo

multicêntrico / Paula Loureiro Cheib Vilefort. Belo Horizonte, 2018.

168 f. : il.

Orientador: Bernardo Quiroga Souki

Coorientadora: Lucia Helena Soares Cevidanes

Tese (Doutorado) – Pontifícia Universidade Católica de Minas Gerais. Programa

de Pós-Graduação em Odontologia

1. Ortodontia interceptora. 2. Aparelhos ativadores. 3. Má oclusão de angle

classe II. 4. Tomografia computadorizada por raios x. 5. Imagem tridimensional.

6. Traumatismos dentários. I. Souki, Bernardo Quiroga. II. Cevidanes, Lucia

Helena Soares. III. Pontifícia Universidade Católica de Minas Gerais. Programa

de Pós-Graduação em Odontologia. IV. Título.

CDU: 616.314-089.23





Tese apresentada ao Programa de Pós-graduação em

Odontologia da Pontifícia Universidade Católica de

Minas Gerais, como requisito parcial para obtenção

do título de Doutor em Odontologia, Área de

Concentração: Clínicas Odontológicas.

COMPOSIÇÃO DA BANCA EXAMINADORA:

1- Prof. Dr. Rogério Lacerda dos Santos – UFJF

2- Prof. Dr. Camilo de Aquino Melgaço – UNINCOR

3- Profa. Dra. Vânia Eloísa de Araújo Silva – PUC Minas

4- Prof. Dr. Amaro Ilídio Vespasiano Silva – PUC Minas

5- Prof. Dr. Bernardo Quiroga Souki – PUC Minas

DATA DA APRESENTAÇÃO E DEFESA: 14 de março de 2018

A tese, nesta identificada, foi aprovada pela Banca Examinadora

Prof. Dr. Bernardo Quiroga Souki Prof. Dr. Rodrigo Villamarim Soares Orientador Coordenador do Programa de Pós-graduação

em Odontologia

Ao meu orientador

que acreditou e me mostrou que eu seria capaz,

e ao meu amado marido

que nunca falha na missão de me apoiar e me sustentar em amor e alegria.

AGRADECIMENTOS

À Deus a minha diária e eterna gratidão pelo dom da vida e por me fazer saber e sentir

que Ele está ao meu lado todo o tempo, me abençoando com saúde, capacidade e disposição.

Aos meus pais por serem minha fonte de apoio e meu porto seguro. À Cida, minha sogra

querida e amiga, que nunca esquece de mim durante suas orações e preces. Tenho certeza de

que elas foram imprescindíveis para que eu chegasse até aqui. Aos meus irmãos, familiares e

amigos queridos. A torcida de vocês é incentivo para mim! Ao Alex por caminhar todos os

dias ao meu lado, mesmo que a milhares de quilômetros de distância, tornando essa

caminhada muito mais leve e feliz; seu amor por mim foi peça fundamental, não me deixando

desanimar diante das dificuldades e fazendo com que elas parecessem muito menores do que

realmente eram para mim. Obrigada por compreender, com paciência, minhas ausências, me

incentivar e me fazer mais forte para correr atrás nos nossos planos. Grande privilégio eu

tenho de te ter como parceiro, ensinando-me sempre sobre alegria, gratidão e esperança.

Ao meu orientador Prof. Bernardo Quiroga Souki que foi meu maior incentivador e

exemplo. Sua inteligência incomum, capacidade de orientar, alegria em ensinar e sua

organização fizeram de mim uma profissional melhor. Facilmente observo e admiro sua

elevada exigência, infinita paciência e persistência, zelo e empenho em tudo o que faz. Serei

eternamente grata por cada passo que dei, onde, de perto ou de longe, agindo ou somente me

vendo agir, me apoiou e me ensinou muito mais que ortodontia.

À Prof. Lucia Helena Soares Cevidanes por tamanho aprendizado de vida e

profissional. Obrigada pela recepção, orientação e oportunidades. Muito grata também pela

parceria e ricos ensinamentos recebidos pelo Prof. Antônio Carlos de Oliveira Ruellas, Dra.

Marília Yatabe, Dr. Marcos Ioshida e Prof. James McNamara.

Agradeço ao Prof. Alexandre Moro e sua aluna de Mestrado Letícia Farah, da

Universidade Positivo, a parceria e confiança depositados em mim, para o desenvolvimento

desse trabalho. E aos alunos do Mestrado em Ortodontia da PUC Minas, Patrícia de Souza

Costa, Juliana Macêdo de Mattos, Karine Sayure Okano, Paula Moreira Oliveira e Lucas

Santana pela preciosa ajuda, e grande parceria.

Agradeço a todos os professores do Programa que de formas distintas e pessoais

transmitiram conhecimento e enriqueceram a minha formação como pesquisadora. Em

especial ao Prof. Dr. Martinho Campolina Rebello Horta e ao Prof. Dr. Rodrigo Villamarim

Soares que conduziram a coordenação do Programa com afinco e dedicação durante o meu

Doutoramento.

Agradeço aos colegas de doutorado e mestrado, pela amizade e parceria. Foi muito

bom poder caminhar com cada um de vocês.

E por fim à CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior),

por me proporcionar uma bolsa de estudo durante meu período no Brasil e durante meu

período na Universidade de Michigan (EUA), através do Programa de Doutorado Sanduíche

no Exterior (PDSE).

“O correr da vida embrulha tudo.

A vida é assim: esquenta e esfria, aperta e daí afrouxa, sossega e depois desinquieta.

O que ela quer da gente é coragem.” (GUIMARÃES ROSA, 1986)

RESUMO

O aparelho Herbst (AH) é um dos dispositivos mais utilizados como opção terapêutica no

tratamento das más oclusões de Classe II. Apesar de já existirem evidências na literatura de

que o tratamento da Classe II deveria incorporar o pico do período puberal de crescimento,

uma parcela dos ortodontistas e dos estudos clínicos científicos da atualidade ainda têm

realizado essa modalidade de tratamento de maneira precoce, durante a fase pré-puberal.

Algumas razões podem ser atribuídas a isto como por exemplo, fator psicossocial e risco

aumentado de traumatismo dentário. Ainda existem alguns questionamentos sobre a eficácia e

eficiência de um tratamento realizado de maneira precoce ou não, em relação a todas as

estruturas do complexo dentofacial, especialmente devido às limitações de metodologia de

imagens bidimensionais (2D) de estudos prévios. O objetivo desse estudo foi investigar as

alterações tridimensionais (3D) dentoesqueléticas do complexo facial (mandíbula, maxila e

relação côndilo-fossa mandibular), após o uso do AH em dois diferentes momentos do estágio

de maturação biológica de crescimento. Uma amostra proveniente de banco de dados de dois

centros universitários foi utilizada e dividida em quatro grupos: (1) Grupo Herbst Puberal –

GHP; 2) Grupo Comparação Puberal – GCP; 3) Grupo Herbst Pre-puberal – GHPP; e 4)

Grupo Comparação Pre-puberal – GCPP. Utilizando software gratuitos (ITK-SNAP 2.2;

Slicer CMF 4.0), modelos virtuais 3D foram construídos a partir de TCFC de crânio

estendido, realizadas em dois tempos; no início do tratamento e após um intervalo de 8 a 12

meses. Superposições em regiões de interesse (base do crânio, maxila, mandíbula e fossa

mandibular) foram realizadas em nível de voxel. Análises utilizando medições entre pontos

anatômicos de referência, superposições com semi-transparências e mapas por código de

cores associados à vetorização foram realizados. Cálculo amostral e análise estatística foram

feitos para cada etapa desse estudo, separadamente. A correlação de concordância intra-classe

foi utilizada para a análise da confiabilidade das leituras. Análises de erro sistemático (teste T

pareado) e aleatório (fórmula de Dahlberg), e a verificação dos pressupostos de normalidade

na distribuição das variáveis (Kolmogorov-Smirnov) foram realizados para a escolha dos

testes de comparação entre os grupos. Pacientes tratados com o AH apresentaram um

significante deslocamento anterior do pogônio (P <0.05), sem giro no sentido horário da

mandíbula. Além disso, o côndilo e porção posterior do ramo apresentaram maior crescimento

superior e posterior (P <0.05). Na maxila, independentemente do estágio de maturação, o AH

promoveu distalização e controle vertical dos molares (P <0.05) e verticalização dos incisivos.

Os efeitos esqueléticos na maxila foram mais expressivos durante o período pré-puberal (P

<0.05). Não foram encontradas mudanças clinicamente significativas, em nenhum dos

estágios de maturação biológica, na relação côndilo-fossa mandibular. Conclui-se que após o

tratamento com o AH realizado durante diferentes estágios do período puberal, distinto padrão

de magnitude e direção de crescimento e deslocamento mandibular e maxilar podem ser

observados. Efeitos dentoalveolares foram mais expressivos e independem do estágio de

maturação esquelética. Efeitos esqueléticos maxilares foram maiores durante o estágio pré-

puberal. A relação côndilo-fossa mandibular não se altera após o uso do AH.

Palavras-chave: Ortodontia interceptora. Aparelhos ativadores. Má oclusão de Angle Classe

II. Tomografia Computadorizada por raios X. Imagem tridimensional.

ABSTRACT

The Herbst appliance (HA) is one of the most frequently used devices worldwide in the

treatment of Class II malocclusion in contemporary orthodontics. Although several studies

have already reported that the treatment of Class II should include puberty in the treatment

plan, a large number of orthodontists still decide for an early approach of Class II, during the

pre-puberty period. Some reasons could be attributed for the decision of early treatment, as

psychosocial factors, and the increased risk of maxillary incisors traumatic injury. Gaps in the

knowledge of the effects of the HA can be attributed to the limitations of the two-dimensional

(2D) methodology. The aim of the current study was to investigate the three-dimensional (3D)

dentoskeletal changes of the facial complex (mandible, maxilla and condyle-glenoid fossa

relationship), after the use of HA at two stages of biological maturation. From the database of

two university centers, the sample was divided into four groups: (1) Herbst pubertal group -

HPG; 2) Comparison pubertal group - CPG; 3) Herbst pre-pubertal group - HPPG; and 4)

Comparison pre-pubertal group - CPPG. Using open-source software (ITK-SNAP 2.2; Slicer

CMF 4.0), 3D virtual models were built from the CBCT’s. Superimpositions in regions of

interest (anterior cranial base, maxilla, mandible, and glenoid fossae) were performed at the

voxel level, and analyzes using point-to-point measurements, semi-transparent overlays, and

color mapping associated with vectorization were done. Sample size calculation and statistic

analysis were done for each section of this study. Intra class correlation coefficients were

performed to test agreement. Random error (Dahlberg`s formula) and systematic error (paired

t-test) were also assessed. Kolmogorov-Smirnov was used to test the normal distribution.

Parametric or non-parametric tests were used accordingly. HA patients showed a significant

anterior displacement of pogonion (P <0.05), with no clockwise mandibular rotation.

Moreover, the condyle and posterior surface of rami presented greater superior and posterior

growth (P <0.05). For the maxilla, independently the stage of biological maturation, the AH

promoted distalization and vertical control of the molars (P <0.05) and uprighting of the

incisors. The maxillary skeletal effects were greater during the pre-pubertal stage (P <0.05).

No clinically significant changes were found in the condyle-fossa relationship during any

biological maturation stages. It was concluded that following HA treatment, performed during

different stages of pubertal period, distinct patterns of magnitude and direction of maxillary

and mandibular growth and displacements could be expected. Dentoalveolar effects were

greater than skeletal ones, independently the skeletal maturation stage. Skeletal maxillary

effects were greater during the pre-pubertal stage. The condyle-glenoid fossa relationship was

not altered after HA treatment, regardless the stage of skeletal maturation.

Keywords: Interceptive orthodontics. Activator appliances. Class II Angle malocclusion.

Cone beam computed tomography. Three-dimensional imaging.

SUMÁRIO

1 INTRODUÇÃO ................................................................................................................... 19

2 REFERENCIAL TEÓRICO .............................................................................................. 23

2.1 Displasia óssea de Classe II: época ideal para a terapia ortopédica ............................ 23

2.2 Ativador mandibular tipo Herbst ................................................................................... 24

2.3 Mudanças na ATM associadas ao uso de ativadores mandibulares ............................ 25

2.4 O uso de Tomografia Computadorizada de Feixes Cônicos na Ortodontia ............... 27

3 HIPÓTESES ........................................................................................................................ 29

4 OBJETIVOS ........................................................................................................................ 31

4.1 Objetivos gerais ................................................................................................................ 31

4.2 Objetivos específicos ......................................................................................................... 31

5 MATERIAL E MÉTODOS ............................................................................................... 33

5.1 Amostra ............................................................................................................................. 33

5.2 Protocolo de instalação e ativação do aparelho ............................................................. 35

5.3 Método de registro ............................................................................................................ 39

5.4 Método de medida ............................................................................................................ 39

5.5 Método de análise ............................................................................................................. 58

6 ARTIGO CIENTÍFICO 1 ................................................................................................... 59

7 ARTIGO CIENTÍFICO 2 ................................................................................................... 85

8 ARTIGO CIENTÍFICO 3 ................................................................................................. 119

9 CONSIDERAÇÕES FINAIS ............................................................................................ 143

REFERÊNCIAS ................................................................................................................... 145

ANEXO A - 1º Parecer Consubstanciado do CEP PUC Minas ....................................... 153

ANEXO B - 2º Parecer Consubstanciado do CEP PUC Minas ........................................ 155

ANEXO C - Artigos científicos publicados ou aceitos em periódicos durante o curso de

Doutorado .............................................................................................................................. 157

ANEXO D - Capítulos de livros publicados durante o curso de Doutorado ................... 163

ANEXO E - Demais produções técnicas feitas durante o curso de Doutorado............... 165

ANEXO F - Trabalhos publicados em anais de eventos (resumo) durante o curso de

Doutorado .............................................................................................................................. 167

19

1 INTRODUÇÃO

As displasias ósseas de Classe II têm elevada prevalência em todo o mundo

(EMRICH; BRODIE; BLAYNEY, 1965; PROFFIT; FIELDS; MORAY, 1998; SANTOS et

al., 2012; LAGANÀ et al., 2013), sendo que a deficiência de crescimento sagital da

mandíbula é o fator etiológico mais associado a este tipo de má oclusão (McNAMARA

JUNIOR, 1981; PANCHERZ; ZIEBER; HOYER, 1997). Tratamentos utilizando dispositivos

ortopédicos removíveis e fixos tem sido preconizados há muitas décadas com o intuito de

normalizar a relação sagital interarcos e obter uma melhora no perfil facial de pacientes em

crescimento (PANCHERZ, 1979; COZZA et al., 2006).

O aparelho Herbst (AH), apresentado por Emil Herbst no início do século XX

(HERBST, 1932), se trata de um ativador mandibular fixo muito utilizado na Europa e

Estados Unidos desde sua reintrodução na literatura por Hans Pancherz algumas décadas mais

tarde (PANCHERZ, 1979). A baixa dependência de colaboração do paciente (PANCHERZ,

1979), bem como a previsibilidade dos resultados clínicos fizeram com que esse aparelho

ganhasse popularidade e aceitação entre os clínicos para a correção da Classe II (RUF;

PANCHERZ, 1999). Diversos aspectos do uso do AH e de seus efeitos biológicos foram

investigados e estão disponíveis na literatura (RUF; PANCHERZ, 1998; PANCHERZ; RUF;

KOHLHAS, 1998; McNAMARA JUNIOR.; PETERSON; PANCHERZ, 2003; KINZINGER;

KOBER; DIEDRICH, 2007; BOOIJ et al., 2013; FRANCHI et al., 2013; PANCHERZ et al.,

2014; SILVA et al., 2014). Existem evidências sobre a remodelação óssea do côndilo e o

aumento do comprimento mandibular após o tratamento com o AH (ALMEIDA et al., 2006;

SERBESIS-TSARUDIS; PANCHERZ, 2008). Além disso, estudos relataram também sobre a

projeção de incisivos inferiores, inclinação lingual dos incisivos superiores, mesialização e

extrusão dos molares inferiores e distalização e intrusão dos molares superiores (SILVA

FILHO; AIELLO; FONTES, 2005; ALMEIDA et al., 2006).

Apesar de extensa literatura ter sido gerada sobre os efeitos dentários e esqueléticos do

tratamento com o AH (PANCHERZ, 1997; HÄGG; DU; RABIE, 2002; HANSEN, 2003;

VANLAECKEN et al., 2006; BARNETT et al., 2008), até o presente momento, a maioria dos

estudos que avaliaram as mudanças associadas ao tratamento com o AH foram baseados em

exames utilizando imagens bidimensionais como radiografias cefalométricas em norma lateral

da face e radiografias transcranianas (PANCHERZ, 1979; PAULSEN, 1997; PANCHERZ;

RUF; KOHLHAS, 1998; PANCHERZ; FISCHER, 2003; ALMEIDA et al., 2006; HÄGG et

al., 2008; SERBESIS-TSARUDIS; PANCHERZ, 2008; PANCHERZ; BJERKLIN;

20

HASHEMI, 2015), ou ainda através de imagens de ressonância magnética (RUF;

PANCHERZ, 1998; RUF; PANCHERZ, 1999; RUF; PANCHERZ, 2000; RUF; WÜSTEN;

PANCHERZ, 2002; AIDAR et al., 2006; KINZINGER et al., 2006; KINZINGER; KOBER;

DIEDRICH, 2007; AIDAR et al., 2009; AIDAR et al., 2010). Sabe-se que métodos de

registro radiográficos bidimensionais estão sujeitos às limitações operacionais como

magnificação da imagem, sobreposição de estruturas ósseas, distorções, posição inadequada

do paciente no momento da tomada radiográfica, e viés do examinador ao sobrepor duas

imagens em tempos diferentes. Dessa maneira, esses métodos de registro têm baixa

reprodutibilidade, não permitindo uma avaliação confiável pelas superposições de estruturas

ósseas (LeCORNU et al., 2013). Para a ressonância magnética, a dificuldade e o desconforto

do paciente ao realizar o exame, o elevado custo e o fato de que esta não é o padrão ouro para

avaliação de tecidos duros, descrevem as limitações desse tipo de exame.

Com o surgimento da tomografia computadorizada de feixes cônicos, um novo campo

na pesquisa surgiu, permitindo entender o que de fato acontece nas estruturas avaliadas após

um tratamento ortodôntico, já que uma superposição volumétrica, e consequentemente, uma

verdadeira avaliação tridimensional é possível com o uso deste tipo de exame. Alguns estudos

(PAULSEN et al., 1995; PAULSEN; KARLE, 2000; VanLAECKEN et al., 2006; MAIA;

RAVELI; SANTOS-PINTO, 2010; BORGES, 2013; LeCORNU et al., 2013; YILDIRIM;

KARACAY; ERKAN, 2014; SESSIRISOMBAT, 2015; CHEN, et al., 2016; WEIWEI et al.,

2016; SAH et al., 2017) utilizaram a TCFC para a avaliação das mudanças esqueléticas após o

uso do AH. Entretanto eles apresentam limitações em sua metodologia já que, em sua grande

maioria, não utilizaram modelos de superposição verdadeiramente tridimensionais (3D) e/ou

apresentaram amostras com tamanho reduzido e ausência de cálculo amostral.

Estudos prévios (RUF; PANCHERZ, 2003; RUF, 2006; PERINETTI et al., 2015;

PERINETTI et al., 2016) relataram que o momento ideal para o tratamento da má oclusão de

Classe II deveria incluir a puberdade, a fim de alcançar um resultado mais eficaz e eficiente.

Existem evidências que o pico de crescimento mandibular coincide com o pico do

crescimento puberal e que o pico do crescimento mandibular ocorre entre os estágios CS3 e

CS4 da maturação das vértebras cervicais (COZZA et al., 2005; BACCETTI; FRANCHI;

McNAMARA JUNIOR, 2005). Logo, o tratamento da Classe II visando o estímulo do

crescimento mandibular se beneficiaria desse estágio biológico de maturação. No entanto,

muitos clínicos continuam tratando seus pacientes portadores de má oclusão de Classe II de

maneira precoce, antes do pico puberal de crescimento (ALMEIDA et al., 2015). Seja por

questões psicossociais, risco aumentado de traumatismo dentário devido a overjet acentuado

21

ou por fatores etiológicos diversos, como por exemplo, má oclusão de Classe II causada por

excesso maxilar.

Outro aspecto ainda pouco documentado e que permanece em discussão entre os

clínicos (IVORRA-CARBONELL et al., 2016) é uma eventual desadaptação do

posicionamento condilar em sua fossa mandibular, após o tratamento com o AH, podendo

levar à mordida dupla, recidivas da correção sagital, e disfunções têmporo-mandibulares.

Considerando que toda a região da articulação temporomandibular sofre modificações por

crescimento e desenvolvimento tridimensional ao longo da maior parte das duas primeiras

décadas de vida (ZARB, 2000; BUMANN; LOTZMANN; MAH, 2002), as avaliações das

mudanças relativas dos côndilos em relação às suas próprias fossas mandibulares precisam

levar em consideração a necessidade de superposições volumétricas 3D.

Sendo assim, justificam-se investigações adicionais por meio de metodologia 3D,

como objetivo de avaliar as mudanças dentoesqueletais no complexo facial, após o período

terapêutico com o AH, tratados em dois momentos diferentes da maturação biológica.

23

2 REFERENCIAL TEÓRICO

2.1 Displasia óssea de Classe II: época ideal para a terapia ortopédica

A displasia óssea de Classe II apresenta uma prevalência de aproximadamente 20%,

sendo a segunda má oclusão mais prevalente (SANTOS et al., 2012; BOURZQUI et al.,

2012). A retrusão mandibular está presente em 70% dos casos contribuindo como fator mais

comum para a discrepância sagital esquelética. Todavia, existem ainda má oclusões de Classe

II causadas pelo excesso de crescimento ântero-posterior da maxila ou ainda pela associação

desses dois fatores (McNAMARA JUNIOR, 1981; TANG; WEI, 1993).

Considerando-se a época do tratamento, dois protocolos de tratamento de Classe II são

utilizados na Ortodontia contemporânea: precoce ou tardio (KING et al., 1990). O tratamento

precoce, feito em duas fases, inicia-se ainda na fase de dentadura mista inicial com uma

abordagem ortopédica, na tentativa de se conseguir uma remodelação esquelética. É

necessária uma contenção dos resultados até que o paciente atinja a fase de dentadura

permanente, onde é feita a fase ortodôntica de finalização (SILVA FILHO; AIELLO;

FONTES, 2005).

No protocolo de tratamento tardio, o início do tratamento é adiado até a fase de

dentadura permanente, coincidindo com o surto puberal de crescimento. Nesse protocolo, a

idade óssea é mais relevante que a idade cronológica ou dentária. Existem evidências que a

incorporação da terapia ortopédica da má oclusão de Classe II na fase puberal de crescimento

favoreça a eficácia e a eficiência. Segundo Baccetti, Franchi e McNamara Junior (2005) este

estágio de maturação corresponde aos estágios de maturação das vértebras cervicais (CS3 e

CS4), avaliado por radiografia lateral cefalométrica. No protocolo de tratamento tardio da má

oclusão de Classe II, também é necessária a segunda fase ortodôntica de finalização.

Entretanto não há um intervalo de tempo entre as fases, excluindo-se a necessidade de

contenção dos resultados parciais da fase ortopédica, e assim diminuindo o tempo total do

tratamento e as chances de recidivas (SILVA FILHO; AIELLO; FONTES, 2005).

Nos pacientes portadores de más oclusões de Classe II por deficiência mandibular, o

deslocamento terapêutico anterior da mandíbula é fator importante na melhora facial. Este

ganho facial é, em tese, alcançado pelo estímulo do crescimento diferencial favorável do

côndilo, ramo e fossa mandibular. Todavia, estudos utilizando avaliação bidimensional

(BURHARDT; McNAMARA JUNIOR; BACCETTI, 2003; BARNETT et al., 2008) e

tridimensional (LeCORNU et al., 2013) relatam não haver crescimento mandibular adicional

24

significante após o uso do AH. Em contrapartida, há na literatura muitos artigos que

utilizaram avaliação bidimensional e avaliação histológica para relatar um crescimento maior

na superfície posterior do côndilo e do ramo mandibular. Peterson e McNamara Junior (2003),

através de um estudo histológico realizado em macacos, relataram ter encontrado significativo

aumento do crescimento na superfície posterior e póstero-superior do côndilo e aumento

significativo da aposição óssea na borda posterior do ramo.

2.2 Ativador mandibular tipo Herbst

Estima-se que o AH seja o mais utilizado na correção das más oclusões esqueléticas

de Classe II na América do Norte (SILVA et al., 2015). Ele foi apresentado por Emil Herbst

no início do século XX (HERBST, 1932) e foi reintroduzido na literatura por Hans Pancherz

no final da década de 1970 (PANCHERZ, 1979). Desde então, esse dispositivo ortopédico

tem sido utilizado por muitos clínicos no tratamento de pacientes portadores de má oclusão de

Classe II com severa deficiência mandibular (RUF; PANCHERZ, 2000). Suas vantagens

clínicas e seus efeitos ortopédicos já têm sido testados e comprovados por muitos

pesquisadores. Por ser um aparelho fixo que mantém a mandíbula continuamente posicionada

anteriormente, sua resposta ortopédica é conseguida através da remodelação da articulação

temporomandibular (ATM) e do aumento no comprimento mandibular (SILVA FILHO;

AIELLO; FONTES, 2005).

Algumas pesquisas avaliaram também seus efeitos maxilares, tanto dentários como

esqueléticos, (HÄGG; DU; RABIE, 2002; HANSEN, 2003; VanLAECKEN et al., 2006;

BARNETT et al., 2008). Há uma concordância na literatura quanto às alterações provocadas

nos componentes dento-alveolares maxilares. Tem-se relatos que os incisivos superiores

foram retruídos e lingualizados (ALMEIDA et al., 2006; NAHÁS et al., 2008). Os molares

superiores foram inclinados para a distal (SILVA FILHO; AIELLO; FONTES, 2005;

NAHÁS et al., 2008) e tiveram sua irrupção restringida no sentido inferior (ALMEIDA et al.,

2006; BARNETT et al., 2008; HAGG et al., 2008; NAHÁS et al., 2008). Porém, a capacidade

do AH causar efeitos esqueléticos ainda é tema de debate na literatura. Alguns estudos

relataram que o AH não induziu uma restrição do crescimento alveolar (ALMEIDA et al.,

2006; NAHÁS et al., 2008; BARNETT et al., 2008). Outros trabalhos discordam com estes

resultados e relatam que o tratamento com o AH provocou uma restrição no comprimento

maxilar (SILVA FILHO; AIELLO; FONTES, 2005; VAN LAECKEN et al., 2006) e no seu

25

deslocamento para frente e para baixo (HÄGG; DU; RABIE, 2002; VAN LAECKEN et al.,

2006). Tal efeito auxiliaria na aquisição de uma melhor relação sagital com a mandíbula.

Não depender da colaboração do paciente é uma vantagem clínica importante

observada no uso desse tipo de aparelho. Em contrapartida, os aparelhos funcionais

removíveis estão sujeitos à cooperação do paciente e, muitas vezes, esse é o motivo que leva

ao insucesso do tratamento (PANCHERZ, 1979).

2.3 Mudanças na ATM associadas ao uso de ativadores mandibulares

O objetivo geral de um tratamento de uma má oclusão de Classe II por deficiência

mandibular é obter um posicionamento mais anterior da mandíbula (PANCHERZ; RUF;

KOHLHAS, 1998; SERBESIS-TSARUDIS; PANCHERZ, 2008). Essas mudanças podem ser

alcançadas através de três mecanismos associados à ATM (separadamente ou a combinação

das três): 1) crescimento mandibular por remodelação condilar; 2) deslocamento anterior da

mandíbula pela remodelação da anatomia da fossa mandibular; e 3) deslocamento anterior da

mandíbula pela rotação e translação condilar dentro da fossa (PANCHERZ; FISCHER, 2003;

SERBESIS-TSARUDIS; PANCHERZ, 2008). Entretanto existem controvérsias acerca dos

mecanismos associados à remodelação côndilo-fossa da ATM após a terapia com o AH

(PANCHERZ, 1979; RUF; PANCHERZ, 1999).

Existem relatos na literatura que afirmam que o tratamento com o AH favorece o

crescimento mandibular em comparação com uma amostra de pacientes sem tratamento

(PANCHERZ, 1979; RUF; PANCHERZ, 1998; HÄGG; DU; RABIE, 2002). Serbesis-

Tsarudise e Pancherz (2008) concluíram que um tratamento com o AH oferece um efeito

ortopédico sagital favorável numa avaliação de curto prazo. Além disso, Ruf e Pancherz

(1998) observaram também que houve uma remodelação óssea durante o período do

tratamento na região anterior da espinha pós-glenóide e, em maior quantidade, na região

póstero-superior do côndilo.

Estudos que utilizaram a radiografia cefalométrica para avaliação das mudanças

encontradas no côndilo após o uso do AH observaram que o crescimento condilar foi dirigido

horizontalmente para trás, com magnitude três vezes maior do que no grupo controle sem

tratamento (PANCHERZ; RUF; KOHLHAS, 1998; SERBESIS-TSARUDIS; PANCHERZ,

2008). Paulsen (1997) observou mudanças na morfologia e presença de um contorno duplo na

parte distoposterior do côndilo e também, em alguns casos, na superfície distal do ramo

interpretando-as como uma remodelação óssea. Nos estudos de Ruf e Pancherz (1998) e Ruf e

26

Pancherz (1999) foi observada uma remodelação óssea na parte mais póstero-superior da

cabeça do côndilo e na superfície anterior da fossa mandibular. Relatou-se que o crescimento

condilar durante o tratamento foi cinco vezes maior e que apresentou uma direção de

crescimento relativamente mais horizontal comparado com o grupo controle que não recebeu

tratamento e que apresentavam uma oclusão ideal. Observou-se, ainda, que a relação côndilo-

fossa não foi afetada pela terapia com o AH.

Ruf e Pancherz (2000), utilizando a ressonância magnética para a avaliação das

mudanças encontradas no crescimento condilar e sua relação com a fossa mandibular,

relataram que o côndilo apresentou um deslocamento estatisticamente significativo mais

anterior na fossa mandibular imediatamente após a remoção do aparelho (T2) em comparação

com a posição inicial em T1 (antes da instalação do aparelho). Entretanto, depois de um ano

que o aparelho havia sido removido (T3), o côndilo retornou para sua posição inicial.

Kinzinger et al. (2006) e Kinzinger, Kober e Diedrich (2007) usaram um aparelho

ortopédico funcional fixo e, através de imagens de ressonância magnética, observaram que o

côndilo se deslocou mais para região inferior e anterior logo que o aparelho foi instalado, mas

que retornou para sua posição original no final do tratamento. Os autores afirmaram que a

reconstrução 3D da superfície do côndilo e suas superposições mostraram que houve um

mecanismo de adaptação e que a melhora na oclusão foi alcançada através de um

reposicionamento fisiológico da ATM (KINZINGER et al., 2006; KINSINGER; KOBER;

DIEDRICH, 2007).

Durante a presente revisão de literatura, foram encontrados alguns artigos publicados e

duas dissertações de mestrado utilizando TC no estudo dos efeitos dentoalveolares do AH

(PAULSEN et al., 1995; PAULSEN; KARLE, 2000; BORGES, 2013; LeCORNU et al.,

2013; YILDIRIM; KARACAY; ERKAN, 2014; SESSIRISOMBAT, 2015; CHEN et al.,

2016; WEIWEI et al., 2016; SAH et al., 2017). Nos relatos de casos de Paulsen et al. (1995) e

Paulsen e Karle (2000) foram avaliados pacientes adultos jovens, após o pico de crescimento

puberal, em que o crescimento endocondral já havia cessado. Foram encontrados contornos

duplos na fossa mandibular e na parte disto-superior dos côndilos durante o tratamento com o

AH, caracterizando uma neoformação óssea dessa região. Yildirim, Karacay e Erkan (2014)

avaliaram a resposta condilar após o uso de 8 meses do aparelho funcional removível Twin-

Block e concluíram que esse aparelho aumenta o volume condilar, o comprimento mandibular

e a distância condilar estimulando o crescimento para cima e para trás do côndilo. Estudos

prévios utilizando avaliação tridimensional de LeCornu et al. (2013) e BORGES (2013)

relataram ter sido observada reabsorção óssea na parede anterior e aposição óssea na parede

27

posterior da fossa, coerentes com a direção de deslocamento condilar após a instalação do

AH. Entretanto, esses estudos apresentam diferenças metodológicas como período de

observação, tipo de aparelho/ancoragem e estágio de maturação dos pacientes em relação ao

modelo de estudo que foi utilizado pela amostra deste pesquisa aqui apresentada.

2.4 O uso de Tomografia Computadorizada de Feixes Cônicos na Ortodontia

Diante do grande avanço científico para o diagnóstico diferencial, a tomografia tem

sido utilizada largamente nas diversas áreas de saúde como um aliado indispensável em casos

de maior complexidade, principalmente por permitir visualizar estruturas com maior acurácia

e uma definição admirável. Permite também, a montagem de secções multiplanares e uma

visão tridimensional, que possibilitam as delimitações de irregularidades e medidas de alta

precisão bem como a representação exata da região avaliada no exame (GARIB et al., 2007).

O surgimento e aumento na acessibilidade das Tomografias Computadorizadas de Feixes

Cônicos (TCFC), especialmente indicadas para a região dentomaxilofacial (HECHLER, 2008;

TYNDALL; RATHORE, 2008) representaram a abertura de novas perspectivas nas

investigações sobre o tema (SMITH; PARK; CEDERBERG, 2011).

Modelagem virtual 3D é conseguida pelo desenvolvimento de uma representação

matemática de estruturas tridimensionais por meio de programas especializados de

computador. Os modelos podem ser criados automaticamente utilizando algorítimos ou

manualmente através de segmentações threshold utilizando as escalas de cinzas de cada

imagem. Esse segundo método consegue reproduzir estruturas mais fiéis à realidade e já é

uma metodologia consolidada (CEVIDANES; STYNER; PROFFIT, 2006). Modelos virtuais

3D representam um objeto ou estrutura anatômica usando uma coleção de pontos no espaço,

conectados por várias formas geométricas como triângulos, linhas e curvas. Atualmente, a

construção e superposição de modelos virtuais 3D permite uma avaliação real da relação

côndilo-fossa e do deslocamento sofrido pelo côndilo após a inserção do AH tanto

qualitativamente como quantitativamente (LeCORNU et al., 2013).

29

3 HIPÓTESES

a) Hipótese Nula 1: após a terapia com o AH, não há diferenças em relação às

mudanças quantitativas e qualitativas na morfologia e posicionamento da mandíbula;

b) Hipótese Alternativa 1: após a terapia com o AH há diferenças em relação às

mudanças quantitativas e qualitativas na morfologia e posicionamento da mandíbula;

c) Hipótese Nula 2: após a terapia com o AH, não há diferenças entre os grupos de

diferentes estágios de maturação esquelética em relação às mudanças quantitativas e

qualitativas na morfologia e posicionamento da maxila;

d) Hipótese Alternativa 2: após a terapia com o AH há diferenças entre os grupos de


qualitativas na morfologia e posicionamento da maxila;

e) Hipótese Nula 3: após a terapia com o AH, não há diferenças entre os grupos de


qualitativas na relação côndilo-fossa mandibular;

f) Hipótese Alternativa 3: após a terapia com o AH há diferenças entre os grupos de


qualitativas na relação côndilo-fossa mandibular.

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4 OBJETIVOS

4.1 Objetivos gerais

Avaliar tridimensionalmente as mudanças na morfologia e no posicionamento da

maxila, mandíbula, na relação côndilo-fossa mandibular e as alterações dentoalveolares após a

terapia com o AH em diferentes estágios do crescimento puberal.

4.2 Objetivos específicos

a) avaliar e mensurar as mudanças no deslocamento total (3D) e linear

(horizontal, vertical e lateral) bem como na morfologia dos côndilos e ramo

mandibular após a terapia com o AH durante o estágio puberal (ARTIGO

CIENTÍFICO 1);

b) avaliar e mensurar a rotação mandibular após a terapia com o AH durante o

estágio puberal (ARTIGO CIENTÍFICO 1);

c) avaliar e mensurar as mudanças no deslocamento e na morfologia da maxila

após a terapia com o AH durante os estágios pré-puberal e puberal e compará-

las (ARTIGO CIENTÍFICO 2);

d) avaliar e mensurar as alterações dentoalveolares maxilares após a terapia

com o AH durante o estágio pré-puberal e puberal e compará-las (ARTIGO

CIENTÍFICO 2);

e) avaliar e mensurar as mudanças na relação côndilo-fossa mandibular após o

uso do AH, nos estágios pré-puberal e puberal de maturação (ARTIGO

CIENTÍFICO 3).

33

5 MATERIAL E MÉTODOS

A metodologia apresentada nessa seção é o detalhamento de todas as etapas seguidas

para obter os resultados de todos os objetivos dessa pesquisa. Alguns detalhes metodológicos

específicos de cada artigo serão descritos na seção de Materiais e Métodos de cada um deles.

5.1 Amostra

Essa investigação é classificada como um estudo observacional retrospectivo de coorte

e ela foi submetida e aprovada pelo Comitê de ética e pesquisa em humanos da PUC Minas

sob os números CAAE 21534013.8.5137 e 79957417.5.0000.5137 (ANEXOS A e B).

Para cada etapa desta pesquisa foi realizado um cálculo amostral específico, sempre

considerando um alfa (α) de 5% e um beta (β) de 20%, para se atingir uma poder de 80%. Foi

aceito um effect size de até 1. Em cada artigo está descrito detalhadamente essa cálculo.

O banco de dados de duas instituições de ensino (Pontifícia Universidade Católica de

Minas Gerais – PUC Minas; e Universidade Positivo – Curitiba- PR) foi acessado e pacientes

que atendiam aos critérios de inclusão e exclusão desse estudo foram incluídos nessa amostra

(Fig. 1 e 2).

Os critérios de inclusão foram:

a) presença de má oclusão de Classe II com retrognatismo mandibular

identificado pela indicação clínica de avanço terapêutico da mandíbula;

b) overjet ≥ 6 mm;

c) discrepância sagital dentária de no mínimo 4 mm, medida na região dos

primeiros molares permanentes;

d) perfil facial convexo;

e) diferentes estágios de maturação esquelética (puberal ou pré-puberal) avaliado

pelo método das vértebras cervicais (entre CS1 e CS4), sendo essa avaliação

feita pela telerradiografia lateral extraída da TCFC de cada paciente;

f) possuir dois tempos de TCFC com intervalos de 8 a 12 meses entre eles.

Os critérios de exclusão foram:

a) portadores de síndromes, fissuras, deformidades dentofaciais;

34

b) portadores de disfunção temporomandibular;

c) indivíduos que foram submetidos à tratamento ortodôntico prévio onde foi

utilizado Aparelho Extra Bucal e/ou ativadores mandibulares;

Figura 1: Fluxograma de seleção da amostra

Fonte: Elaborada pela autora.

35

Figura 2: Fluxograma da montagem dos grupos avaliados

5.2 Protocolo de instalação e ativação do aparelho

Para as investigações apresentadas nesta tese, os pacientes foram alocados em grupos

de indivíduos tratados com o AH, ou em grupos usados como comparação. Os pacientes dos

grupos “Comparação” também eram portadores de má oclusão de Classe II esquelética mas

não tiveram essa má oclusão corrigida no primeiro momento. Isto ocorreu devido à outras

prioridades de tratamento odontológicos não-ortopédicos, como por exemplo tratamento e

acompanhamento de patologias, tracionamento de dentes impactados ou algum tipo de

tratamento protético/restaurador. Na investigação apresentada no Artigo científico 1, apenas

pacientes em estágio puberal foram incluídos, sendo então gerados os grupos Herbst (GH) e

Comparação (GC). Nos Artigos científicos 2 e 3, foram incluídos os pacientes em estágios

puberal e pré-puberal, formando quatro grupos, sendo denominados Herbst puberal (HP),

Comparação puberal (CP), Herbst pré-puberal (HPP), e Comparação pré-puberal (CPP).


37

Os pacientes dos grupos Herbst foram tratados utilizando o mesmo protocolo, tanto na

PUC Minas como na Universidade Positivo. O aparelho Herbst possuía um sistema do tipo

telescópio da marca Abzil (São José do Rio Preto, São Paulo). Na arcada maxilar um aparelho

expansor tipo Hyrax da marca Morelli (Sorocaba, São Paulo) e na arcada mandibular um arco

lingual de Nance com fio de aço 1,0mm. Tais acessórios objetivaram o aumento da resistência

do dispositivo e da estabilidade do sistema. Diante da discrepância transversal gerada com o

avanço mandibular, o parafuso expansor foi ativado de acordo com as necessidades

individuais, evitando-se as interferências oclusais. Um fio 0,7 mm de aço na oclusal dos

segundos molares permanentes foi acoplado ao sistema para evitar a extrusão desses dentes,

quando presentes (Fig. 3).

Todos os casos seguiram o mesmo protocolo de avanço mandibular, com ativação em

tempo único, objetivando obter uma relação de Classe I de caninos. Aqueles pacientes que

apresentaram interferências no movimento protrusivo e retroinclinação de incisivos

superiores, foram submetidos à alinhamento dentário com aparelho fixo 2x4 na maxila antes

da inserção do AH para permitir a ativação em tempo único.

Figura 3: Design do aparelho Herbst.


39

5.3 Método de registro

TCFC obtidas antes (T0) e ao final de 8 a 12 meses (T1) (média de 10,2 meses) foram

selecionadas de todos os pacientes. As imagens foram obtidas pelo tomógrafo i-CAT

(Imaging Sciences International, Hatfield, Pennsylvania, Estados Unidos) com FOV de 23 cm

x 17 cm (crânio estendido), voxel de 0,3 x 0,3 x 0,3 mm ou 0,4 x 0,4 x 0,4 mm, 36.90 mA,

120 kV e tempo de exposição de 40 segundos.

5.4 Método de medida

Modelos virtuais tridimensionais (3D), construídos a partir das TCFC, permitiram

mensurar as mudanças entre T0 e T1. O processamento das TCFC e dos modelos virtuais foi

feito através dos software ITK-SNAP 2.2 (software de livre acesso, www.itksnap.org),

SLICER CMF 4.0 (software de livre acesso, www.slicer.org). Para tanto, as tomografias

foram submetidas a uma série de processamentos que incluíram seis etapas:

a) Construção dos modelos 3D: utilizando a ferramenta Intensity Segmenter (Slicer

CMF 4.0), labelmaps (segmentações) das estruturas anatômicas ósseas foram

identificadas baseadas na imagem obtida pela TCFC em uma escala de cinzas, e

modelos tridimensionais volumétricos do crânio foram construídos. Utilizando o

ITK-SNAP 2.2 os ajustes e edições necessárias nos labelmaps foram feitos;

b) Orientação das cabeças: para comparar os dados de todos os pacientes em um

mesmo sistema de coordenadas, o modelo 3D T0 de todos os pacientes foi

posicionado espacialmente utilizando planos de referência padronizados para cada

plano do espaço: o plano axial foi determinado pelos pontos pórion esquerdo e

direito e pela mediana dos pontos orbital direito e esquerdo; o plano sagital

passou pela crista galli e pelo ponto médio da curvatura anterior do forame

magno; e o plano coronal tangenciou o tuberculum da sela túrcica. A orientação

do modelo T0 em uma localização espacial padronizada produziu uma matriz

matemática individual que pode ser aplicada nos scanT1 gerando a mesma

orientação do crânio para todos os dois tempos e para todos os pacientes (Fig. 4);

c) Superposição 3D na base do crânio: a superposição 3D consistiu de duas etapas

(Slicer CMF 4.0): a) aproximação manual dos scans (Fig. 5 e 6) e b) o registro

volumétrico automático baseado em voxel (Fig. 7). Para o registro na base do

40

crânio, os scans T0 e T1 foram manualmente aproximados, tendo como referência

a melhor superposição possível das estruturas da fossa craniana anterior,

especificamente das superfícies endocranianas da região da crista cribiforme do

osso etmóide e na superfície interna do osso frontal. Essas regiões foram

escolhidas já que seu crescimento finaliza-se muito cedo na vida das crianças. A

fase do registro foi feita de maneira totalmente automatizada, baseada em voxels.

O software computou o registro rígido (translação e rotação) que alinha as escalas

de cinzas de T0 e T1 a partir dos dados obtidos pela TCFC, com uma elevada

acurácia, em nível de voxel, na região anterior da base do crânio. Esse registro é

delimitado por uma máscara (uma referência volumétrica) criada a partir do

modelo 3D T0. Essas máscaras volumétricas informam ao software em qual

região os voxels de dois tempos diferentes (T0 e T1) devem se sobrepor;

d) Superposição regional 3D da mandíbula, maxila e fossa craniana: de maneira

similar ao registro feito na base do crânio, a superposição regional da mandíbula,

maxila e fossa mandibular requerem uma aproximação manual prévia dos scans, e

a partir daí um registro automático baseado em voxel (Slicer CMF 4.0). Para a

mandíbula, os scans T0 e T1 foram aproximados tendo como referência a melhor

sobreposição possível das linhas externas do corpo da mandíbula nas três vistas da

tomografia (axial, coronal e sagital). Para a etapa do registro, a máscara utilizada

incluiu o corpo da mandíbula, exceto os dentes e a cortical externa da superfície

inferior do corpo e da sínfise mandibular. O limite posterior da máscara é um

plano adjacente à superfície anterior do ramo, perpendicular à borda inferior da

mandíbula (Fig. 8). Para a maxila, os scans T0 e T1 foram aproximados tendo

como referência a linha inferior do palato duro numa vista sagital e o assoalho da

cavidade nasal numa vista frontal. A máscara utilizada na maxila incluiu a região

do palato duro, excluindo a região dentoalveolar, indo até a linha que passa pelos

forames palatinos (RUELLAS et al., 2016). Para o registro regional na fossa

mandibular, primeiramente os scans T0 e T1 foram aproximados tendo como

referência a borda inferior da fossa mandibular. A máscara foi confeccionada

contendo toda a porção anatômica da fossa mandibular (Fig. 1 do ARTIGO

CIENTÍFICO 3);

e) Avaliações qualitativas utilizando modelos 3D: avaliações qualitativas do

crescimento e do deslocamento maxilar, mandibular e da fossa mandibular, além

das mudanças dentárias, foram feitas através do software SLICER, utilizando a

41

técnica de superposição com semi-transparência de modelos virtuais 3D T0 e T1

(Fig. 9), e mapas por código de cores associados a vetorização de direção e

magnitude de crescimento e deslocamento como exemplificado nas Figuras 10 e

11.

f) Avaliações quantitativas utilizando modelos 3D: a avaliação quantitativa foi

realizada através de uma ferramenta chamada Q3DC (Slicer CMF 4.0). Para tal,

identificação de pontos de referência (landmarks) pelo software ITK-SNAP 2.2

foi realizada previamente. Para evitar erros associados à localização desses pontos

de referência nos modelos virtuais 3D, landmarks tridimensionais, com o tamanho

de um voxel (0,3 mm), foram cuidadosamente plotadas simultaneamente nas três

vistas multiplanares (axial, coronal e sagital), bem como utilizando o modelo 3D

do crânio para conferência final (Fig. 12). Utilizando cores distintas, landmarks

foram colocadas na maxila, mandíbula e fossa mandibular que estarão

especificadas em cada artigo correspondente.

43

Figura 4: Orientação do crânio nas três vistas: sagital, coronal e axial (Software

SLICER).


45

Figura 5: Tomografias sobrepostas antes da aproximação (Software SLICER).


47

Figura 6: Tomografias sobrepostas após a aproximação na base do crânio (Software

SLICER).


49

Figura 7: Registro em nível de voxel da base do crânio T0. A) T0; B) T1; C) registro de

T1 em T0.


51

Figura 8: Região de sínfise mandibular funcionando como máscara para realizar o

registro regional da mandíbula em nível de voxel.


53

Figura 9: Método de superposição com semi-transparência dos modelos virtuais T0 e T1

demonstrando mudanças que ocorreram imediatamente após à instalação do AH.


55

Figura 10: Mapas por código de cores.


57

Figura 11: Associação do método por mapas por código de cores com o método de

correspondência por forma: vetores indicando direção e magnitude de crescimento.

Figura 12: Identificação de landmarks nos dentes, nas três vistas e no modelo 3D

(Software ITK-Snap).



58

5.5 Método de análise

A análise dos dados foi conduzida utilizando o software estatístico SPSS (versão 21.0;

SPSS, Chicago, IL, EUA). Foi realizada uma exploração geral dos dados com estatística

descritiva. O teste Kolmogorov-Smirnov indicou que a maioria das variáveis não atendia aos

pressupostos de normalidade e, por isso, para a comparação entre os grupos foi utilizada uma

estatística não-paramétrica (testes de Mann-Whitney, Kruskall-Wallis e Wilcoxon). A

concordância entre as leituras intra e inter-examinadores foi feita utilizando o teste ICC. As

análises de erro foram feitas com o teste t pareado (erro sistemático), e a fórmula de Dalhberg

(erro aleatório). Para isto, foram feitas releituras dos dados de 15 pacientes com intervalo de 1

mês para cada seção desta pesquisa (mandíbula, maxila, relação côndilo-fossa mandibular). O

nível de significância foi estabelecido em 5%.

59

6 ARTIGO CIENTÍFICO 1

Three-dimensional skeletal mandibular changes associated with Herbst appliance

treatment

Publicado no periódico Orthodontics Craniofacial Research em Maio de 2017.

Esse artigo foi formatado respeitando as normas da revista presente no link abaixo:

http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1601-6343

60

Three-dimensional skeletal mandibular changes associated with Herbst appliance

treatment

BQ Souki1, PLC Vilefort

1, DD Oliveira

1, I Andrade Junior

1, AC Ruellas

2, MS Yatabe

3, T

Nguyen4, L Franchi

5, JA McNamara Jr

6, LHS Cevidanes

6

Pontifical Catholic University of Minas Gerais, Belo Horizonte, Brazil1

Federal University of Rio de Janeiro, Rio de Janeiro, Brazil2

University of Sao Paulo, Bauru, Brazil3

University of North Carolina, Chapel Hill, USA4

University of Florence, Florence, Italy5

University of Michigan, Ann Arbor, USA6

Correspondence to:

Bernardo Souki

Pontifical Catholic University of Minas Gerais

Av. Dom José Gaspar, 500 Coração Eucarístico Belo Horizonte Brazil (30535-901).

Phone: 55-31-32455108

E-mail: [email protected]

61

Abstract

Objectives: Three-dimensional evaluation of skeletal mandibular changes following Herbst

appliance treatment. Setting and Sample Population: Retrospective case–control study, based

on a sample size calculation. Twenty-five pubertal patients treated with Herbst appliance

(HAG), and 25 matched Class II patients who received other non-orthopaedic dental

treatments (CG). Material and Methods: Three-dimensional models were generated from pre-

treatment (T0) and post-treatment (T1) cone beam computed tomograms. Volumetric

registration on the cranial base was used to assess mandibular displacement; volumetric

regional registration was performed to evaluate mandibular growth. Quantitative

measurements of X, Y, Z and 3D Euclidian changes, and also qualitative visualization by

colour-mapping and semi-transparent overlays were obtained. Results: Downward

displacement of the mandible was observed in both HAG and CG (2.4 mm and 1.5 mm,

respectively). Significant forward displacement of the mandible was observed in the HAG

(1.7 mm). HAG showed greater 3D superior and posterior condylar growth than the CG

(3.5 mm and 2.0 mm, respectively). Greater posterior growth of the ramus was noted in the

HAG than in CG. Conclusions: Immediately after Herbst therapy, a significant mandibular

forward displacement was achieved, due to increased bone remodelling of the condyles and

rami compared to a comparison group. Three-dimensional changes in the direction and

magnitude of condylar growth were observed in Herbst patients.

62

Introduction

The primary goal of Herbst appliance therapy is to correct Class II malocclusion and

improve facial convexity (1-3). Numerous clinical studies (4-9) have reported a short-term

increase in mandible length and forward displacement of the mandible. Furthermore,

histological animal studies corroborated these findings by showing growth modification of the

mandibular condyle and ramus following Herbst treatment (10-11). Much debate still exists,

however, as to whether the bite jumping mechanism has the capacity of stimulating greater

mandibular growth and consequently forward displacement of the mandible (12-15).

To date, the majority of Herbst studies were performed using two-dimensional (2D)

cephalometric imaging, an approach that cannot explain adequately the complex interactions

of three-dimensional (3D) changes that occur with growth and treatment (16). In a recently

published systematic review (14) concerning the changes in the TMJ morphology in Class II

patients treated with fixed mandibular repositioning evaluated with 3D imaging, the authors

concluded that previous literature has “failed to establish conclusive evidence of the exact

nature of TMJ tissue response”. The authors suggested the development of an adequate

sample size CBCT 3D investigation, using valid and reliable superimposition technique to

quantify bone remodeling.

Therefore, the aim of this retrospective study was to compare the mandibular skeletal

changes in pubertal Class II patients treated with Herbst appliance versus orthopedically-

untreated Class II controls, using a 3D virtual modeling protocol.

Materials and methods

Sampling

This investigation is a retrospective study that followed the ethical standards of the

institutional review board of Pontifical Catholic University of Minas Gerais, Belo Horizonte,

63

Brazil. The primary focus was to evaluate increases in condylar growth during Herbst therapy.

Based on the standard deviation of 1.85 mm reported by Pancherz et al. (17), an alpha

significance level of 0.05 and a power of 0.80 to detect changes of 1.5 mm, a sample size of

25 patients per group was calculated. The total sample included 50 skeletal Class II pubertal

patients.

Patients had been treated at the graduate program in orthodontics of the Pontifical

Catholic University of Minas Gerais and were considered eligible for this study when they

had routine pre-treatment (T0) and post-treatment (T1) CBCTs acquired for the purpose of the

orthodontic or dental diagnosis and treatment planning. Moreover, the patients at T0 were: 1)

in the permanent dentition; 2) age between 12 and 16 years old; 3) in the pubertal growth

period, as determined by the Cervical Vertebrae Maturation Method (18); 4) with Class II

division 1 malocclusion characterized by full Class II molar relationships, and canines that

had at least 4 mm sagittal discrepancy to achieve a Class I relationship; 5) and an improved

facial profile when the mandible was postured in a forward position (19).

Twenty-five patients who had received one-step mandibular activation with a

cantilever Herbst to obtain a Class I canines relationship were included in the Herbst

appliance group (HAG). The remaining 25 subjects were assigned to the comparison group

(CG). The patients in the CG had the need for other dental treatments or an orthodontic

leveling and alignment of maxillary teeth, without dentofacial orthopedic effects. At T0, no

significant different morphologic characteristics were detected between HAG and CG patients

(p>0.05). The Herbst patients presented with an ANB of 6.4°±1.2°, SNB of 72.4°±2.1°, and

SNGoGn of 32.1°±2.2°. The Comparison Group patients had an ANB of 5.9°±1.0°, SNB of

73.0°±3.0° and SNGoGn of 32.0°±2.6°.

64

Image Acquisition

Cone Beam Computed Tomographic (CBCT) scans had been taken for all subjects,

using an iCat machine (Imaging Sciences International, Hatfield, PA), with a 40-second scan,

a 23 x 17 cm field of view (FOV), and a voxel size of 0.3 mm. In the HAG, the scans were

taken before HA delivery (T0) and after 7.9 ± 0.4 months of treatment (T1). In the CG, the

scans were taken at two time-points: at baseline (T0), and at the end of the orthodontic or

prosthetic treatment, during the follow-up of impacted canine treatment, or after maxillary

cyst marsupialization. The average time between films in CG was 8.4 ± 1.3 months. All

patients had been instructed to bite into centric occlusion during scan acquisition.

Image analysis

The 3D image analysis procedures followed the protocol that has been published

elsewhere (20-23), which included the following: (1) construction of 3D surface models (20);

(2) 3D model orientation in the Cartesian planes (20-21); (3) 3D cranial base superimposition

for the mandibular displacement analysis (20); (4) 3D mandibular regional superimposition

(manual approximation and automated registration on the body of the mandible) for the

mandibular growth analysis (22); (5) qualitative assessments using 3D mesh surface models

(20, 23); and (6) quantitative measurements using Pick-n’-Paint and Q3DC tools of 3D Slicer

(20, 24).

Statistical analysis

Fourteen scans were selected randomly, and models were rebuilt and re-measured by

two blinded investigators after a two-week interval. Random error was measured according to

Dahlberg’s formula, and both intra and inter-observer agreement measurements were tested

using intraclass correlation coefficients (ICC).

65

Systematic error was assessed using the paired t-test. To evaluate the differences

between the Herbst and Comparison groups with regard to T1-T0 changes, independent

sample t-tests with Holm-Bonferroni correction for multiple tests were used. Analysis of

covariance (ANCOVA) was conducted with the mean T0-T1 change in the several ROI’s as

the dependent variables, group of treatment as the independent variable, and SNGoGn angle

as the covariate. Chi-square test was used to assess differences in the gender distribution. The

level of significance was set at 0.05.

Results

The two groups were matched by gender (HAG, 11 males vs. CG 15 males, chi-square

P > 0.05), chronological age (13.7 ± 1.8 years for HAG vs. 13.9 ± 1.2 years for CG), stage of

dental development, stage of skeletal maturation (88% in CS3 or CS4), and by length of

observational period (8 months). In each group, 2 patients were in stage CS2 and 1 patient

was in stage CS5.

The ICCs were greater than 0.89 for both intra- and inter-observer repeated

measurements. There were no statistically significant systematic errors between the 2

measurements performed by the same operator (p>0.05), and random error values varied

between 0.07 mm (3D condyle anterior) and 0.18 mm (3D condyle superior).

Mandibular displacement and rotation in HAG and CG is shown in Table 1. The

condylar and ramal growth changes in the right and left side were symmetrical, with no

statistically significant difference between sides in both groups (Table 2). Mean differences in

mandibular and ramal growth between the HAG and CG are reported in Table 3.

Fig. 1 shows the mandibular displacement with the cranial base superimposition of

HAG and CG individuals, while Figures 2 and 3 show the pattern of growth of the condyle

66

and rami with color-coded with regional superimposition. The skeletal mandibular changes

associated with Herbst treatment can be summarized as follows:

The forward displacement of the mandible was greater in the HAG

Pogonion showed a significant anterior displacement (Y axis) in the HAG (HAG, 2.2

mm vs. CG, 0.5 mm; mean difference, 1.7 mm; Table 1, Figure 1). The 3D displacement was

significantly greater in the HAG (HAG, 3.7 mm vs. CG, 2.2 mm; mean difference, 1.5 mm).

Both groups showed a similar (p>0.05) downward (Z axis) mandibular displacement (2.4 mm

vs. 1.5 mm in the HAG and CG, respectively). Changes in mandibular pitch were minimal in

both groups (mean 0.1° clockwise; 95% CI from -2.1° to 2.3° in the HAG vs. 0.3°

counterclockwise 95% CI from -2.5° to 2.0° in the CG group). Fifteen patients in the HAG

showed clockwise pitch, while 11 patients in the CG showed clockwise pitch.

Patients in the HAG presented a different pattern of condylar growth

The 3D net growth of condyles in all surfaces was significantly greater in the HAG

(superior, 1.4 mm; lateral 1.1 mm; medial, 0.5 mm; anterior 1.3 mm; posterior, 1.2 mm; Table

3, Figs. 2 and 3), with the exception of the medial pole. Patients in the HAG showed more

posterior and superior condylar growth than the CG (p<0.05), with the exception of the

vertical growth of the medial condylar pole (Table 3). The right-left lateral skeletal changes

did not show statistically significant differences between groups.

The posterior surface of the rami in the HAG showed greater amounts of posterior

growth

The Herbst group showed a statistically significant greater net change for the lower

region of the ramus in the projected Y component (0.6 mm; Fig. 3). The vertical and lateral

67

growth of the mandibular ramus (Z and X axis, respectively) was not significantly different

between the groups. 3D net changes in the superior (neck) region of the rami did not show

statistically significant differences between HAG and CG.

Discussion

Previous reports on the net gain of mandibular advancement are controversial.

Pancherz (8) reported 2.5 mm of Pogonion advancement when compared to an untreated

sample of Class II sample after 6 months of HA treatment. However, 16 years later, Pancherz

et al. (17) reported only a 0.9mm gain in the position of Pogonion in the Herbst group in

comparison to values from the Bolton Standards (2.2 mm vs. 1.3 mm). De Almeida et al. (25)

did not find statistical difference in the Pogonion position between treated and control

patients. In our study, the net mean of 1.5 mm increment (HAG 3.7 mm vs. CG 2.2 mm) in

mandibular anterior displacement in the projected y-axis may have contributed to facial

profile improvement, as well as correction of the malocclusion that was observed clinically in

all HAG patients.

Our findings concerning the 3D directional components of the mandibular growth and

displacement relative to the cranial base revealed 2.4 mm downward displacement of the

Pogonion region. Pancherz et al. (17) reported that Herbst treatment produced 3.9 mm of

downward displacement of the Pogonion region. Differences in appliance design using

mandibular first premolars as anchorage in the Pancherz study (17) versus first molars in the

present study may have resulted in differences on the point of force application and improved

control of vertical growth in the present study.

The results of this investigation suggest that condylar and ramal growth are modified

with Herbst appliance treatment. Our findings indicated that in the superior region and the

posterior surface of the condyles showed 1.4 mm and 1.2 mm greater growth in the HAG than

68

the CG over an 8-month period. The 3D components of bone remodeling, however, were not

uniform along the whole condylar surface. As was expected from a morphological and

functional standpoint, changes in the shape of the mandible typically take place during normal

growth. Such morphological changes in the shape and position of the condyles were observed

in most of the HAG and CG subjects.

The amount of effective condylar growth in Herbst subjects found in the current 3D

investigation (1.4 mm in the superior aspect of the condyles) was very close to data reported

previously in 2D cephalometric studies that used Condylion as reference landmark. Pancherz

(17) reported 1.8 mm of effective condylar growth in the Herbst groups. Another study (25)

found 2.5 mm of supplementary mandibular length increase in Herbst patients. The relatively

smaller net differences in condylar growth observed in the present study can be explained by:

1) the stage of skeletal maturation of the patients; 2) differences in the control groups; and 3)

the methods of registration and measurement.

The short observational period in the current investigation could account for the

relatively small skeletal changes. However, previous Herbst studies using 2D imaging have

shown greater skeletal changes with even shorter observational periods (6 months). The 3D

condylar growth, ranging between 2 and 3 mm observed in the HAG in this study cannot be

considered small. As the CG showed 3D condylar growth ranging between 1 and 2 mm,

however, the net differences were not as high as described previously in the literature. The

growth of the rami posteriorly was significantly greater in the HAG. Although 0.6 mm in the

inferior region of the rami might be considered small from a clinical point of view, this

perspective can change if the short observation period is taken into account. Significant bone

deposition along the posterior border of the ramus has been reported in experimental studies

with juvenile rhesus monkey (11).

69

Conclusions

Immediately after Herbst therapy, significant more mandibular forward displacement

without pitch was achieved, due to increased bone remodeling of the condyles and rami

compared to an untreated sample. Herbst patients presented different magnitude and direction

of condylar growth as contrasted to comparison patients.

Acknowledgment

The authors would like to acknowledge the CAPES (Coordenação de Aperfeiçoamento de

Pessoal de Nível Superior – “Coordination for higher Education Staff Development”) and

CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico – “National Counsel

of Technological and Scientific Development”) for their financial support.

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73

Figures

Fig. 1. Cranial base volumetric superimposition and the 3D models semi-transparent overlays.

A) Anterior cranial base superimposition mask. B) Full face displacement after Herbst

appliance treatment. C) Mandibular displacement in comparison group individual. D)

Mandibular displacement after Herbst appliance treatment.

75

Fig. 2. Semi-transparent overlays of the 3D models (T0, red; and T1, black mesh), and closest

point color maps in the qualitative assessment of the condylar growth (mandibular regional

superimposition). A) Herbst appliance patient. B) Comparison group patient.

77

Fig. 3 Shape correspondence color mapping with vectors in the qualitative assessment of the

condylar and rami growth (mandibular regional superimposition). A) Herbst appliance

patient. B) Comparison group subject.

79

Table 1. Comparison of mandibular displacement (T1-T0) in Herbst appliance and Comparison groups (t-test and ANCOVAa). Cranial base superimposition.

ROI Coordinates Groups Mean SD Mean difference CI 95% T-test p value

F Groups

F SNGoGn

Pogonion X

Herbst -0.37 0.65 -0.29 -0.85 0.25 0.279 2.056 0.073

Comparison -0.08 0.46

Y Herbst 2.20 1.31 1.66 0.74 2.60

0.001** 14.396** 0.088 Comparison 0.54 1.34

Z Herbst 2.37 1.6 0.90 -0.21 2.03

0.110 2.134 1.897 Comparison 1.47 1.64

3D Herbst 3.68 1.55 1.46 0.42 2.49

0.007** 8.052** 1.833

Comparison 2.22 0.43

Mandible

Pitch Herbst 0.06 0.6 0.35 -0.20 0.90

0.207 1.853 0.926 Comparison -0.29 0.95

Notes: a ANCOVA indicates analysis of covariance; SD, standard deviation; CI 95%, confidence interval of 95%; X, mesial-lateral; Y, anterior-posterior; Z superior-inferior; (+), rightward, forward, downward, clockwise

rotation; (-), leftward, backward, upward, counterclockwise rotation.

* p<0.05; ** p<0.01

Pitch is defined as clockwise and/or counterclockwise rotation in a lateral view.

80

Table 2. Condylar and rami growth after Herbst appliance therapy with the comparison between right and left sides (t-test). Mandibular regional superimposition.

Continuação

Herbst Group Comparison Group

Right Side Left Side Right Side Left Side

ROI Coordinates Mean SD Mean SD T-test

p value Mean SD Mean SD T-test

p value

Condyle Superior

X 0.53 0.48

0.53 0.49 0.948

0.44 0.31

0.49 0.29 0.684

Y 1.87 1.13

1.95 0.99 0.473

0.72 0.95

0.67 1.16 0.603

Z 2.55 0.95

2.61 1.17 0.783

1.67 1.28

1.64 1.08 0.820

3D 3.39 1.18

3.50 1.28 0.599

2.03 1.4

2 1.43 0.866

Condyle Lateral

X 0.87 0.55

0.54 0.60 0.103

0.42 0.34

0.5 0.58 0.621

Y 0.97 0.58

0.95 0.61 0.869

0.33 0.38

0.31 0.37 0.846

Z 2.56 0.87

2.62 1.03 0.823

1.56 1.2

1.56 1.1 0.819

3D 2.4 1.41

2.01 1.1 0.194

1.17 0.92

1.29 1.04 0.598

Condyle Medial

X 0.97 0.45

0.86 0.66 0.425

0.63 0.44

0.77 0.71 0.214

Y 2.19 1.5

2.47 1.35 0.092

0.85 0.96

1.08 1.3 0.152

Z 1.81 0.75

1.77 1.03 0.856

1.3 0.89

1.24 0.77 0.649

3D 2.21 1.31

2.55 1.6 0.297

1.63 1.12

2.01 1.5 0.122

Condyle Anterior

X 0.43 0.38

0.47 0.39 0.717

0.53 0.42

0.44 0.48 0.569

Y 1.80 1.22

1.89 1.04 0.542

0.66 0.76

0.82 1.11 0.244

Z 1.83 0.77

1.80 1.18 0.906

1.16 0.98

1.07 0.62 0.653

3D 2.70 1.16

2.71 1.31 0.975

1.43 0.98

1.37 1.25 0.784

Condyle Posterior

X 1.30 0.86

1.19 0.83 0.361

0.71 0.62

0.85 0.78 0.193

Y 1.16 0.95

1.23 0.82 0.625

0.5 0.5

0.54 0.76 0.768

Z 2.26 0.87

2.20 0.83 0.746

1.49 0.75

1.5 0.77 0.639

3D 2.80 1.27

2.68 1.02 0.532

1.51 1.15

1.62 1.29 0.689

Rami Neck X 0.97 0.56

0.80 0.67 0.385

0.64 0.4

0.77 0.73 0.375

81

Y 0.70 0.60

0.74 0.51 0.625

0.26 0.26

0.24 0.18 0.139

Z 1.03 0.71

0.90 0.48 0.659

1.03 1.08

0.76 0.63 0.423

3D 1.40 1.16

1.37 0.74 0.851

1.22 1.16

1.04 0.95 0.515

Rami Posterior

X 0.63 0.62

0.62 0.85 0.912

0.44 0.26

0.46 0.36 0.999

Y 0.82 0.48

0.86 0.57 0.751

0.20 0.15

0.26 0.21 0.996

Z 0.95 0.93

0.91 0.82 0.703

0.72 0.79

0.54 0.45 0.954

3D 1.52 1.11

1.47 0.96 0.754

1.21 1.16

1.03 0.95 0.976

Notes:

X: mesial-lateral, Y: anterior-posterior; Z: superior-inferior

(+): lateral, backward, upward

82

Table 3. Comparison of condylar and rami changes (T1-T0) in Herbst appliance and Comparison groups (t-test and ANCOVAa) Continuação

83

Conclusão

Notes: a ANCOVA indicates analysis of covariance; SD, standard deviation; CI 95%, confidence interval of 95%; X, mesial-lateral; Y, anterior-posterior; Z superior-inferior; (+), rightward, forward,

downward, clockwise rotation; (-), leftward, backward, upward, counterclockwise rotation, *p<0.05; **p<0.01.,

85


Maxillary dentoskeletal changes following Herbst appliance treatment in pre-

pubertal and pubertal stages

Esse artigo será submetido para publicação no periódico The Angle Orthodontist

(Qualis A2) e ele foi formatado respeitando as normas da revista presente no link abaixo:

http://www.angle.org/page/submit?code=angf-site

86

Maxillary dentoskeletal changes following Herbst appliance treatment in pre-pubertal

and pubertal stages

Paula Loureiro Cheib-Vileforta; Lucia Helena Soares Cevidanes

b; Patricia de Souza Costa

c;

Marilia Sayako Yatabed; Antonio Carlos de Oliveira Ruellas

b; James A. McNamara Jr.

e;

Alexandre Morof, Bernardo Quiroga Souki

g

aPhD Student, Graduate Program in Dentistry, Pontifical Catholic University of Minas Gerais, Belo

Horizonte, Brazil. bAssociate Professor, Department of Orthodontics and Pediatric Dentistry, School of Dentistry,

University of Michigan, Ann Arbor, Mich. cPrivate Practice, Former resident of Orthodontics, Pontifical Catholic University of Minas Gerais,

Belo Horizonte, Brazil. dResearch Fellow, Department of Orthodontics and Pediatric Dentistry, School of Dentistry,

University of Michigan, Ann Arbor, Mich. e Thomas M. and Doris Graber Endowed Professor of Dentistry Emeritus, Department of

Orthodontics and Pediatric Dentistry, School of Dentistry; Professor Emeritus of Cell and

Developmental Biology, School of Medicine; Research Professor Emeritus, Center for Human

Growth and Development, The University of Michigan, Ann Arbor, Mich; and Private Practice, Ann

Arbor, Mich. fAssociate Professor, Federal University of Parana, Graduate Program in Dentistry, University

Positivo; and Private Practice, Curitiba, Brazil. gAssociate Professor, Graduate Program in Dentistry, Pontifical Catholic University of Minas Gerais,

Belo Horizonte, Brazil; and Private Practice, Belo Horizonte, Brazil.

Mailing address:

Bernardo Quiroga Souki

Av. Dom José Gaspar 500 – Coração Eucarístico

Belo Horizonte – MG – Brazil - CEP 30535-901

Phone: +55 31 3319-4414

Email: [email protected]

87

ABSTRACT

Objective: To assess the maxillary dentoskeletal changes associated with the Herbst

appliance (HA) treatment. Materials and Methods: 3D virtual surface models were

generated from CBCT scans of 41 Class II patients treated with HA, and 37 Class II

comparison patients. According to the skeletal age, four groups were composed: 1) Pubertal

Herbst Group – PHG, n=21; 2) Pubertal Comparison Group – PCG, n=16; 3) Pre-pubertal

Herbst Group – PPHG, n=20; and 4) Pre-pubertal Comparison Group – PPCG; n=21. Total

and regional volumetric superimpositions of the scans were performed. Point-to-point

measurements of the displacements of dental and skeletal landmarks, in the X, Y, Z and 3D

perspectives, provided the quantitative data. Color maps and semitransparent overlays

offered the qualitative analysis. Non-parametric statistics were used. Results: Restriction of

the forward displacement of A-point (0.7 mm), and restriction of the downward

displacement of ANS (0.6 mm) was found in PPHG (P < .05). No significant skeletal

maxillary changes were found in the PHG. HA did not impact the maxillary downward

displacement of PHG and PPHG patients. Relative to the maxilla, the molars of HA patients

had a significant vertical control. Incisors were uprighted (approximately 2.3 degrees, P >

.05) and molars were distalized (approximately 1.2 mm, P < .05) in both HA groups. In the

Herbst groups, pre-pubertal patients showed greater dental compensations, but without

significant statistical difference. Conclusions: HA treatment provided some restriction of

the anterior and inferior maxillary growth and the effects were more evident in the pre-

pubertal patients than in the pubertal patients. Maxillary dentoalveolar changes were

observed in all patients regardless the stage of maturation.

KEYWORDS: Angle Class II Malocclusion; Maxilla; Herbst Appliance; Cone Beam

Computed Tomography.

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INTRODUCTION

The Herbst appliance (HA) treatment aims to correct the convex profile of Class II

malocclusion patients associated with mandibular deficiency. Notable scientific efforts have

been already applied in order to understand the biological effects of this appliance.1–3

Due to

the fact that the mechanism of action of the HA is focused on the mandible, the literature

about this topic is mostly dedicated to the mandibular dentoskeletal effects.4–6

Only few

reports are available about the maxillary HA effects.7–9

Critics have been raised on the

effective exclusive mandibular improvements, and in the opinion of some researchers, the

maxillary effects would overcome the mandibular ones, at least in the long term.10,11

There is evidence that the ideal timing to treat mandibular deficiency of Class II

malocclusion patients, using fixed mandibular advancement devices, should include puberty,

in order to achieve a more effective and efficient outcome.12,13

However, the ideal treatment

timing to target maxillary effects could be different, since significant maxillary growth

occurs earlier.14

Regarding the maxilla, the HA effects are skeletal or dentoalveolar? Is there

any difference if the HA treatment is performed before or during the peak of pubertal

growth?

Most findings about HA dentoskeletal effects were based on two-dimensional

analysis.3,7,13,15,16

Such registration method, however, is subject to operational limitations as

bone structures overlap, imaging distortions and examiner`s bias by overlapping two images

from different time-point exams.17,18

Volumetric CBCT superimpositions, in the other hand,

allows a comprehensive assessment of the three-dimensional (3D) dentoskeletal changes

associated with treatments and or facial growth.18–20

A previous 3D pilot study reported a

significant restriction of the maxillary growth after the use of HA by pubertal patients,

comparatively to a group of Class II elastic patients.17

Therefore, this study aims to assess the 3D maxillary dentoskeletal changes associated

with the HA in groups of patients treated in the pre-pubertal and pubertal stages of

maturation.

MATERIALS AND METHODS

Sampling

This study was approved by the Institutional Review Board of the Pontifical Catholic

University of Minas Gerais (PUC Minas), in Belo Horizonte, Brazil. A retrospective cohort

was conducted from February 2011 to December 2014, by means of the database review

89

from graduate programs in orthodontics of two universities in Brazil. The sample size

calculation was based on the standard deviation value of 1.49 mm presented by Manfredi et

al.21

related to the primary aim of this study (A-point sagittal displacement). Considering α

of 5%, and a power of 80%, and to detect maxillary changes greater than 0.6 mm (effect-size

of 0.4), using ANOVA F-test, it was recommended the minimum of 19 individuals in each

group.

Seventy-eight skeletal Class II malocclusion patients who met the eligibility criteria

were included in this cohort. All of them had CBCT scans taken before treatment (T0) and at

the end of the observation period (T1 – mean of 10.2 months later); 37 treated in the pre-

pubertal and 41 in the pubertal stage of maturation. Forty patients had been treated with

cantilever HA (3M Abzil, São José do Rio Preto, Brazil).

The sample was grouped in pubertal (Pubertal Herbst Group – PHG; n=20; 9 girls vs.

11 boys) and pre-pubertal (Pre-pubertal Herbst Group – PPHG; n=20; 7 girls vs. 13 boys)

patients that received HA; and pubertal (Pubertal Comparison Group – PCG; n=16; 8 girls

vs. 8 boys) and pre-pubertal (Pre-pubertal Comparison Group – PCG; n=21; 3 girls vs. 18

boys) comparison patients. Pubertal patients had a mean age of 13.6 years old, and pre-

pubertal patients has a mean age of 9.5 years old. The comparison groups consisted of

patients that received others dental treatments before the orthopedic Class II correction, as

the follow up of impacted tooth, pathological cyst marsupialization treatment, or prosthetic

treatments. The inclusion criteria were that at T0 individuals had: 1) to present full molars

and canines in Class II division 1 relationship; 2) at least, 4 mm of mandibular advancement

to reach a first molar Class I relationship after HA insertion; 3) facial aspect of mandibular

retrusion, 4) to be at pubertal stages of CS3 or CS4 for the pubertal groups, and at stages

CS1 or CS2 for the pre-pubertal groups, 5) presenting CBCT scans before and after HA

treatment (for HA groups). Individuals with craniofacial anomalies were not included in the

sample.

Image Acquisition

All CBCT scans were taken using an iCat machine (Imaging Sciences International,

LLC, Hatfield, PA), with 40 seconds of digitalization, a field of view (FOV) of 23 cm x 17

cm, and a voxel of 0.3 or 0.4 mm. In the pubertal groups, the exams were carried out before

the HA insertion (T0) and 8 to 10 months (SD 1.2 months) after the HA treatment (T1). In

pre-pubertal groups, the exams were carried out at some time point (T0) and 10 to 12

90

months later (SD 1.5 months) (T1). All patients were instructed to bite in centric occlusion

during the acquisition of CBCTs.

Image Analysis

Image analysis protocol has been previously described.22–24

The methodology allows

the volumetric voxel based registration in the anterior cranial base,25

as well in regional

areas of interest. Maxillary regional registration has been described elsewhere.22

The 3D

virtual models of the heads were oriented in the same coordinate system, allowing reliable

comparisons between several patients.26

Open-source software (Slicer CMF 4.0 and ITK-

Snap 2.2) were used. The quantitative assessment of maxillary dentoskeletal changes was

carried out using the Q3DC tool on the Slicer CMF 4.0. From anatomic landmarks

accurately and simultaneously identified and pre-labeled in the multiplanar views (sagittal,

axial and coronal), and confirmed on the 3D surface model, point-to-point measurements

were carried out, quantifying the X, Y, Z and 3D displacements between the T0 and T1

models, relative to the anterior cranial base (ACB). The maxillary dental changes were also

measured relative to the maxillary regional superimposition. Maxillary rotations (pitch, roll,

and yaw) were also evaluated.

A total of seven landmarks were pre-labeled19

in each time-point scan. Three skeletal

landmarks were identified on the maxilla: (1) at anterior nasal spine (ANS); (2) at A-point

(AP); and (3) at the posterior nasal spine (PNS). Four dental landmarks were identified at:

(4) the mid-point of the incisal edge of the permanent right upper central incisor (IE); (5) the

root apex of the permanent right upper central incisor (IRA); (6) the mesio-buccal cusp tip

of the first permanent maxillary molars (MC); and (7) the mesio-buccal root apex of the

same molar (MRA).

Qualitative assessments of the maxillary growth and displacement were carried out

using semi-transparent overlays and shape-correspondence color maps (Figures 1 to 5), with

3D Slicer software tools.


The data analysis was carried out using SPSS version 20.0. To determine the errors in

the identification of landmarks, and in the measurements of the virtual models, 10 scans

were randomly selected, models were rebuilt, and re-measured by two investigators after an

interval of two weeks. The random error was measured according to Dahlberg’s formula34

and an analysis of the reproducibility of the intra-observer and inter-observer measurements

91

was tested using intraclass correlation coefficients (ICC), with a confidence level of 95%.

The systematic error (bias) was assessed using paired t-test. The normality and

homoscedasticity assumptions inspection was carried out by means of Kolmogorov-Smirnov

e Levene tests, respectively. Because most of the variables did not present normal

distribution and same variance, non-parametric comparison of the median values for

independent samples test (Mann-Whitney) was used. It was chosen the level of significance

of 5%.

RESULTS

The ICCs were greater than 0.87 for both intra and inter-observer repeated

measurements. There were no statistically significant systematic errors between the two

measurements performed by the same operator (P > .05).

Descriptive data relative to the maxillary skeletal and dental displacements are

presented in Table 1. The difference between HA groups (PPHG and PHG), and the

differences between these groups and their matched comparison groups (PPCG and PCG,

respectively) are shown in Table 2.

Based on the current findings, the following results can be presented:

Herbst appliance promoted a restriction of the anterior displacement of A-point in pre-

pubertal patients

The A-point showed statistically significant anterior-posterior (Y component)

displacement (P < .01) during the pre-pubertal period (HPPG, 0.28 mm vs. CPPG, 0.96 mm)

but not during the pubertal period (HPG, 0.12 mm vs. CPG, 0.22 mm) (Tables 1 and 2).

ANS and PNS did not show statistically significant anterior-posterior displacement (Table

2). The ANS of pubertal patients moved forward 0.43 mm and 0.54 mm (for Herbst and

Comparison groups, respectively), and 0.47 mm vs. 0.83 mm for the pre-pubertal patients

(Table 1), with P > .05 in the comparison of these groups (Table 2). PNS displaced

backward in all groups (HPG, -0.03 mm; CPG, -0.13 mm; HPPG, -0.24 mm; CPPG, -0.15

mm; P > .05). In Tables 1 and 2, positive signals means that the landmark displaced

anteriorly, while negative signals means that landmarks had posterior displacement between

T0 and T1. Figures 1 to 4 show the visual analysis of the pattern of maxillary displacement

of the four groups. Figures 6 and 7 summarize the difference between HA and comparison

groups, during pubertal and pre-pubertal stages respectively.

92

The Herbst appliance did not influence the downward displacement of the maxilla

ANS, A point and PNS moved downward in all groups, and no major differences were

found in the values of vertical displacement of skeletal landmarks, except to the ANS in the

pre-pubertal period (HPPG, -1.09 mm vs. CPPG, -1.67 mm (Table 1); P < .05 (Table 2)).

The negative signals in all groups means that landmarks had downward displacement

between T0 and T1. Maxillary vertical displacement can be observed in the semi-transparent

overlays and color mapping in the four groups (Figures 1 to 4).

Incisors moved backward in Herbst groups

Relative to the cranial base superimposition the maxillary incisors of treated groups

were statistically significant moved backward (P < .05), (HPG vs. CPG, 0.69 mm; HPPG vs.

CPPG, 1.44 mm), without pitch rotation (clockwise). Relative to the regional maxillary

superimposition the maxillary incisors were distalized 0.55 mm in the comparison of

pubertal groups (PHG vs. CPG), and 0.33 mm in the comparison of pre-pubertal groups

(PPHG vs. CPPG), but without statistically significant differences (P > .05) (Tables 1 and 2,

Figure 6 and 7). No statistically significant pitch rotation was found in the incisors

angulation in the maxillary regional superimposition analysis.

No vertical changes in the position of the incisors were observed

Relative to the cranial base (HPG, -1.84 mm; CPG, -1.53 mm; HPPG, -1.99 mm;

CPPG, -2.62 mm), and to the regional superimposition (HPG, -0.92 mm; CPG, -0.62 mm;

HPPG, -0.69 mm; CPPG, -0.22 mm), the Y component (superior-inferior) of the IE did not

show statistically significant differences (P > .05).

The amount of the molar distalization and tipback were not influenced by the pubertal

stage

Table 1 shows that molars were moved backward approximately 0.9 mm in the

pubertal groups (HPG, -0.86 mm vs. CPG, -0.15 mm – right side; HPG, -1.17 mm vs. CPG,

-0.13 mm – left side); and approximately 1.5 mm in the pre-pubertal groups (HPPG, -1.35

mm vs. CPPG, 0.15 mm – right side; HPG, -1.11 mm vs. CPG, 0.40 mm – left side). The

distalization was greater on the crown than on the root, with a pitch rotation (tipback) of

approximately 3.0 degrees in PHG and 5 degrees in PPHG. No significant differences in the

distalization of the molars were observed between PHG and PPHG.

A vertical control of the molars was observed in the Herbst patients

93

Molars moved downward relative to the cranial base in all groups (Table 1). However,

a statistically significant difference was observed in the amount of the downward

displacement between the HA and comparison groups within the two stages of skeletal

maturation (Table 2). Despite the downward maxilla displacement relative to the cranial

base in all groups, vertical control of the molars was observed in the HA patients. Relative

to the maxillary regional registration, the molars had less vertical displacement in PHG

(right side, 0.70 mm difference HPG vs. CPG; left side, 0.96 mm difference HPG vs. CPG).

These differences (average between sides of 0.84 mm) were statistically significant (P <

.05). Also relative to the maxillary regional registration, the molars in PPHG were vertically

stable (0.00 mm) and in PPCG, they extruded 0.64 mm in PPCG. The difference (0.63 mm)

was also statistically significant.

DISCUSSION

Previous studies on the dentoskeletal effects of the HA treatment have been mainly

focused on the mandibular effects.4–6

But, some researchers have questioned if in fact

maxillary effects would overcome mandibular gains.10,11

Recently, Rogers et al.11

affirmed

that “the primary effect of the Herbst in terms of maxillomandibular correction was in the

maxilla”. Wieslander10

reported a significant maxillary effect of the headgear-Herbst

appliance, concluding that the maxillary sutural remodeling might be more receptive to

long-term orthopedic treatment than the mandibular condylar growth process. But, due to

their small sample size, different orthopedic approach, and individual variability, such

findings should be interpreted with caution. Moreover, these studies used only 2D

assessments and no maxillary regional superimposition. Even with the possible maxillary

dentoskeletal contribution of the HA on the treatment of the Class II malocclusion, most of

the debate about mandibular versus maxillary effects have been presented based on believes

and personal thoughts. The current paper reports the first 3D investigation of the maxillary

effects of HA.

This study findings revealed that pre-pubertal Class II patients treated with the HA

presented more maxillary sagittal influence than pubertal individuals. Pre-pubertal patients

presented a restriction of 0.7 mm of sagittal displacement of A-point relative to the matched

comparison group, while pubertal individuals showed only 0.1 mm of net change. In

agreement, with a sample of 30 pre-pubertal patients, de Almeida et al.27

also found 0.7mm

of A-point restraint after 12 months of HA treatment. But, with a sample of 10 patients,

94

Pancherz28

described that patients treated with HA had 0.4 mm of distalization from the A-

point. Otherwise, some investigations did not find significant maxillary skeletal changes

after HA treatment. A recent systematic review reported that publication bias was detected

in A point measurements.29

And in another systematic review, Barnett et al.30

concluded that

minimal effects were demonstrated on the maxilla. Phan et al.31

reported no restraint of

maxillary growth in patients treated with HA. In the current study, we found 0.5 mm of ANS

growth restriction in pre-pubertal patients treated with HA, but without statistical difference.

However, de Almeida et al27

reported significant 0.8 mm of ANS restraint in their pre-

pubertal patients. As differences are small they may be explained by individual variability

in the different study samples.

The qualitative assessments using overlays with semitransparency, as well as the

color-maps, allow clear visualization of maxillary growth changes with the HA. In these

images, a restriction of the anterior region of the maxilla is observed in the HA groups, and a

forward displacement of the maxilla took place in the comparison groups (Figures 1 to 5).

These findings represent individual findings, while Tables 1 and 2 reveal that only A-point

in the PPHG showed statistically significant result.

For the assessment of 3D skeletal maxillary changes, this study utilized classic

landmarks in cephalometrics as fiducials for skeletal structures, due to their location are at

well-defined areas of maximum surface curvature. Another previous CBCT investigation

have also used ANS, PNS, A-point.17

The assessment of maxillary skeletal displacement as

measures at such landmarks must be carefully interpreted, as it may be a source of error

when maxillary growth changes are expected to happen. Because ANS, PNS and A-point

present independent and variable changes along time, they do not necessarily indicate the

behavior of the whole maxillary growth. The ANS forward displacement does not mean that

the maxillary body moved forward. Moreover, the A-point localization in the alveolar bone

exposes the landmark location to changes associated with the incisors movement. In the

sample of pubertal patients, several individuals had maxillary incisors aligned and leveled

with edgewise brackets, what might have influenced the displacement of A-point. However,

as both HA and comparison groups had similar number of patients with such condition, it

probably did not brought differences between groups.

Evidence-based reports have indicated puberty as the gold-standard timing to

effectively correct the Class II malocclusion using dentofacial orthopedic appliances.13

However, clinicians may need to begin the correction of the excessive overjet due to

psychosocial problems or the increased risk of traumatic injuries in the pre-pubertal stage.32–

95

34 Thus, our sample included patients within the two stages of skeletal maturity (pre-pubertal

and pubertal), in order to understand if maxillary effects of the HA were different in patients

treated with different timing. We have found that pre-pubertal patients in our comparison

group presented more forward and downward maxillary displacement than pubertal subjects

in the comparison group, indicating that maxillary growth is more active during early stages

of maturity. Probably due to the greater maxillary growth potential during pre-puberty,

greater maxillary growth restriction was found in patients treated early with HA. Thus, the

decision for early treatment with the HA can have an additional indication, besides the

previously described special recommendations (risk of trauma, or psychosocial effects), to

achieve maxillary sagittal growth control.

The maxillary anterior region present a downward displacement on the HA groups, of

approximately 1 mm (0.8 mm in PHG, and 1.1 mm in PPHG), while the posterior region

suffered a smaller vertical displacement (0.4 mm in PHG, and 0.6 mm in PPHG). Maxillary

clockwise rotation has been previously reported. Pancherz28

described the clockwise rotation

on the palatine plan, reporting 0.6 degrees in relation to the cranial base. In another study,

Pancherz and Anehus-Pancherz7 confirmed such findings, and reported 2 degrees of occlusal

plane inclination, and 0.2 degrees of palatal plane rotation. In the present study, the

maxillary incisors were vertically displaced 0.45 mm downward in PHG and 0.83 mm in

PPHG, according Table 1. In Pancherz’s study28

, a downward movement of 0.9 mm of the

incisors was described.

The molars vertical behavior in the HA groups was not similar to the comparison

groups. In the superior-inferior direction, we hypothesized that the direction of the forces

generated by the appliance, would lead to molar intrusion. This study results show that the

HA caused a relative intrusion of the molars relative to the cranial base, since in the HA

patients the molars were vertically stable while in the CG patients molars erupted. Such

finding is in accordance with previous 2D studies.14,28

The first permanent molars displaced

laterally significantly (coordinate X), in the Herbst groups (P < .05) due to the rapid

maxillary expansion (RME) included in HA preparation for the mandibular advancement.

A limiting aspect of the current investigation was the inclusion of comparison patients,

instead of control patients. The teeth alignment before HA treatment, as well as the RME

might have influenced the results. The alignment of the incisors and the RME are routinely

performed in order to allow the mandibular advancement. But, because they were performed

in 60% of the Herbst and also comparison patients, it is possible that they were not a bias in

that sample. We can infer that comparison Class II patients who had received tooth

96

movements, other than that target primarily to correct the molars sagittal relationship, might

present some degree of mandibular spontaneous growth aid. If a real control group were

used, probably the differences between HA and comparison groups would be greater.

Moreover, the minor intrusion of the molars observed in the current sample after HA

treatment would be greater if RME had not been carried out in several HA patients.

The significant maxillary molars distalization (puberal, 0.9 mm; pre-pubertal, 1.5 mm)

and tipback crown rotation (puberal, 3°; pre-pubertal, 6.5°), and also to the minor maxillary

skeletal changes helped the correction of the dental Class II relationship. These

measurements were small as Table 1 shows, but are clearly visible with the qualitative 3D

tools. These findings are in accordance with prior studies that compared the HA to the high-

pull headgear appliance, as to restriction effect of the development on the vertical direction

of the upper molars.7,31

Pancherz and Anehus-Pancherz7 concluded that HA had therapeutic

action similar to the headgear conventional applicance.29

Clinically, with the current design

of HA, was not noticed a so remarkable inclination, as with the use of a cervical headgear.

CONCLUSIONS

HA treatment provided some restriction of the anterior and inferior maxillary growth

and the effects were more evident in the pre-pubertal patients than in the pubertal patients.

Maxillary dentoalveolar changes were observed in all patients regardless the stage of

maturation.

ACKNOWLEDGMENT

The authors would like to acknowledge the CAPES and FIP PUC Minas for their financial

support.

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26. Ruellas AC de O, Tonello C, Gomes LR, et al. Common 3-dimensional coordinate system

for assessment of directional changes. Am. J. Orthod. Dentofac. Orthop. 2016;149:645-

656.

27. de Almeida MR, Henriques JFC, de Almeida RR, Weber U, McNamara JAJ. Short-term

treatment effects produced by the Herbst appliance in the mixed dentition. Angle Orthod.

2005;75:540-547.

28. Pancherz H. The effect of continuous bite jumping on the dentofacial complex: a follow-

up study after Herbst appliance treatment of class II malocclusions. Eur. J. Orthod.

1981;3:49-60.

29. Yang X, Zhu Y, Long H, et al. The effectiveness of the Herbst appliance for patients with

Class II malocclusion: A meta-analysis. Eur. J. Orthod. 2016;38:324-333.

99

30. Barnett G a, Higgins DW, Major PW, Flores-Mir C. Immediate skeletal and dentoalveolar

effects of the crown- or banded type Herbst appliance on Class II division 1

malocclusion. Angle Orthod. 2008;78:361-369.

31. Phan KLD, Bendeus M, Hagg U, Hansen K, Rabie ABM. Comparison of the headgear

activator and Herbst appliance--effects and post-treatment changes. Eur. J. Orthod.

2006;28:594-604.

32. O’Brien K, Wright J, Conboy F, et al. Effectiveness of early orthodontic treatment with

the Twin-block appliance: a multicenter, randomized, controlled trial. Part 2:

Psychosocial effects. Am. J. Orthod. Dentofacial Orthop. 2003;124:488-495.

33. O’Brien K. Is early treatment for Class II malocclusion effective? Results from a

randomized controlled trial. Am. J. Orthod. Dentofacial Orthop. 2006;129:64-65.

34. O’Brien K, Macfarlane T, Wright J, et al. Early treatment for Class II malocclusion and

perceived improvements in facial profile. Am. J. Orthod. Dentofac. Orthop.

2009;135:580–585.

101

FIGURES

Figure 1 – Semitransparent overlays of T0 (red) and T1 (black mesh) virtual models of a

pubertal Herbst appliance patient. (A) Cranial base registration, showing a minor backward

and major downward maxillary displacement. (B) Regional maxillary registration, showing

minor backward and downward displacements. Transversal dimensional gain can be

observed associated with RME. The distalization and vertical control of molars can be

observed in semitransparency and color map with shape correspondence method.

103

Figure 2 – Semitransparent overlays of T0 (red) and T1 (black mesh) virtual models of a

pubertal comparison patient. (A) Cranial base registration, showing a minor forward

displacement. (B) Regional maxillary registration, showing no skeletal changes and the

color map with shape correspondence method presented minor forward dental displacement.

105

Figure 3 - Semitransparent overlays of T0 (red) and T1 (black mesh) virtual models of a

pre-pubertal Herbst appliance patient. (A) Cranial base registration, showing minor

backward and major downward maxillary displacement. (B) Regional maxillary registration,

showing the real backward and downward displacement of the maxilla, with no association

with cranial base growth or displacement. Transversal growth could not be observed. The

distalization and vertical control of molars could be observed in semitransparency and color

map with shape correspondence method.

107

Figure 4 - Semitransparent overlays of T0 (red) and T1 (black mesh) virtual models of a

pre-pubertal comparison patient. (A) Cranial base registration, showing minor forward and

downward maxillary displacement relative to the cranial base. (B) Regional maxillary

registration, showing minor skeletal changes. Color map with shape correspondence method

presented an uprighting of the incisors, probably due to the RME. No dental changes of the

molars were found.

109

Figure 5 – Shape Correspondence color mapping with vectorization of the four groups.

Relative to the cranial base, all groups showed downward maxillary displacement but with

different pattern of magnitude. (A) HPG showing minor backward maxillary displacement.

(B) CPG showing minor forward maxillary displacement. (C) HPPG showing more

backward maxillary displacement than HPG. (D) CPPG showing more forward maxillary

displacement that CPG.

111

Figure 6 – Differences between HPG and CPG. The positive sign means that Herbst group

presented greater changes than Comparison group. Negative sign means that Herbst group

presented smaller changes than comparison group. The arrows indicate the net changes

direction for the Herbst groups. The red numbers indicate statistically significant changes.

113

Figure 7 - Differences between HPPG and CPPG. The positive sign means that Herbst

group presented greater changes than Comparison group. Negative sign means that Herbst

group presented smaller changes than comparison group. The arrows indicate the net

changes direction for the Herbst group. The red numbers indicate statistically significant

changes.

115

Table 1. Descriptive data of the skeletal and dental maxillary changes relative to the cranial base, for the four groups (T1 – T0).

PHG PCG PPHG PPCG

Landmarks Coordinate Mean SD Median Mean SD Median Mean SD Median Mean SD Median

ANS

Y 0.43 1.13 0.30 0.54 0.81 0.61 0.47 0.78 0.41 0.83 0.75 0.69

Z -0.98 0.89 -0.75 -1.06 0.63 -0.90 -1.09 0.68 -0.93 -1.67 0.90 -1.94

3D 1.40 1.14 0.79 1.39 0.72 1.27 1.42 0.67 1.20 1.95 1.01 2.34

A Point

Y 0.12 0.39 0.06 0.22 0.82 0.15 0.28 0.62 0.30 0.96 0.77 0.81

Z -0.79 0.90 -1.05 -0.83 0.47 -0.82 -1.05 0.61 -1.14 -1.60 1.06 -1.55

3D 1.10 0.67 1.21 1.17 0.45 1.08 1.29 0.48 1.33 2.01 1.07 2.20

PNS

Y -0.03 0.55 -0.09 -0.13 0.76 0.00 -0.24 0.47 -0.30 -0.15 0.39 -0.09

Z -0.28 0.70 -0.36 -0.72 0.63 -0.66 -0.61 0.77 -0.60 -0.87 0.79 -0.73

3D 0.75 0.51 0.64 0.98 0.73 0.78 1.10 1.16 0.68 1.03 0.70 0.88

ANS-PNS Yaw 0.00 0.04 0.00 0.02 0.06 0.00 0.03 0.07 0.01 -0.03 0.09 -0.01

Pitch -0.35 1.67 -0.36 -0.38 0.57 -0.57 -0.56 0.88 -0.87 -0.94 0.98 -0.77

Incisal Edge

Y -0.44 1.77 -0.64 0.25 1.09 0.60 -0.13 1.60 0.01 1.30 1.16 1.28

Z -1.84 1.31 -1.73 -1.53 1.15 -1.20 -1.99 0.91 -2.10 -2.62 1.42 -2.90

3D 2.53 1.62 2.24 1.97 1.12 1.92 2.72 0.75 2.65 3.10 1.61 3.19

CM

X 1.33 1.20 1.20 0.71 1.21 0.49 0.79 1.10 0.54 0.20 0.56 0.02

Y -0.87 1.91 -1.50 0.25 0.99 0.45 -1.36 1.36 -1.30 1.19 1.01 1.06

Z -0.75 2.08 -0.15 -1.57 1.07 -1.51 -0.90 1.16 -1.05 -2.26 1.37 -2.44

3D 2.83 2.06 2.44 2.29 1.10 2.07 2.57 0.96 2.55 2.82 1.30 2.90

LAI Pitch -3.63 4.24 -4.09 -1.26 3.78 -0.14 -2.95 4.27 -3.90 -0.16 2.71 -0.57

LAM Pitch -3.43 3.78 -3.73 -0.19 2.51 0.33 -5.98 5.20 -4.80 1.25 2.23 1.56

Roll 0.69 2.45 0.02 -0.34 2.87 -0.08 1.26 2.65 0.98 -1.05 1.48 -0.92

Notes:

SD. Standard Deviation; Incisal Edge. Mid-point of the incisal edge of the permanent right upper central incisor; CM. mesio-buccal cusp tip of the permanent maxillary first molar; LAI. Long axis of the permanent right upper central incisor; LAM. Long axis of the permanent maxillary first molar; X. mesial-lateral; Y. anterior-posterior; Z superior-inferior; (+). Rightward; forward; upward; clockwise rotation; (-). Leftward; backward;

downward; counterclockwise rotation.

116

Table 2. Descriptive data of the dental maxillary changes relative to the maxillary superimposition for the four groups (T1 – T0).

PHG PCG PPHG PPCG

Landmarks Coordinate Mean SD Median Mean SD Median Mean SD Median Mean SD Median

Incisal edge

Y -0.43 1.69 -0.78 0.12 1.07 -0.30 -0.07 1.40 0.08 0.26 1.21 0.15

Z -0.92 0.90 -0.62 -0.62 0.43 -0.75 -0.69 0.74 -0.90 -0.22 1.33 -0.58

3D 1.75 1.39 1.32 1.20 0.66 1.08 1.69 0.66 1.63 1.57 1.00 1.34

R CM

X 1.40 1.06 1.38 0.59 1.05 0.45 0.77 0.89 0.49 0.11 0.54 0.00

Y -0.86 1.86 -1.02 -0.15 0.53 0.00 -1.35 1.28 -1.19 0.15 0.78 0.00

Z 0.08 1.80 0.43 -0.63 0.62 -0.62 0.00 1.10 -0.10 -0.30 1.25 -0.46

3D 2.57 1.92 2.25 1.38 0.76 1.38 2.15 1.15 2.02 1.42 0.71 1.42

L CM

X -1.10 0.82 -0.90 -0.54 0.97 -0.60 -0.51 1.14 -0.60 -0.21 0.37 -0.26

Y -1.17 1.13 -1.05 -0.13 0.49 -0.30 -1.11 1.58 -0.84 0.40 0.55 0.30

Z 0.44 0.74 0.53 -0.52 0.43 -0.60 -0.02 1.29 -0.15 -0.97 0.53 -1.02

3D 2.05 0.99 1.98 1.21 0.65 1.12 2.27 1.27 2.00 1.25 0.53 1.37

LAI Pitch -3.44 4.39 -3.64 -1.65 4.27 -0.56 -1.22 5.68 -1.01 0.12 3.09 -0.09

R LAM Pitch -2.92 4.00 -2.73 -0.08 2.45 0.48 -5.52 5.08 -5.06 0.62 2.26 0.36

Roll 0.82 2.46 0.68 -0.40 2.82 -0.39 1.70 3.12 0.61 -0.84 1.50 -0.70

L LAM Pitch -3.54 4.08 -3.24 -0.38 2.37 0.00 -5.45 6.78 -3.75 1.37 1.53 1.01

Roll -0.58 1.95 -0.46 -0.62 2.35 -0.04 -0.23 4.43 -1.82 -0.04 2.13 0.09

Notes:

Incisal Edge. mid-point of the incisal edge of the permanent right upper central incisor; R CM. mesio-buccal cusp tip of the right permanent maxillary first molar; L CM. mesio-buccal cusp tip of the left permanent

maxillary first molar LAI. Long axis of the permanent right upper central incisor; R LAM. Long axis of the right permanent maxillary first molar; L LAM. Long axis of the left permanent maxillary first molar X.

mesial-lateral; Y. anterior-posterior; Z superior-inferior; (+). Rightward; forward; upward; clockwise rotation; (-). Leftward; backward; downward; counterclockwise rotation.

117

Table 3. The mean differences of the skeletal and dental maxillary changes relative to the cranial base in the comparison between the groups.

PHG vs. PCG PHG vs. PPHG PPHG vs. PPCG

Landmarks Coordinates Mean difference SE 95% CI P Value

Mean difference SE 95% CI P Value


ANS Y -0.11 0.33 -0.79 0.56 0.679 0.20 0.29 -0.40 0.80 0.845 -0.51 0.25 -1.02 0.01 0.179 Z 0.07 0.25 -0.44 0.58 0.342 0.33 0.25 -0.19 0.84 0.328 0.63 0.26 0.10 1.16 0.042

3D 0.01 0.31 -0.61 0.63 0.342 -0.19 0.30 -0.80 0.42 0.163 -0.67 0.27 -1.23 -0.11 0.054

A Point Y -0.10 0.22 -0.56 0.36 0.842 -0.17 0.21 -0.60 0.26 0.425 -0.69 0.25 -1.21 -0.18 0.003 Z 0.03 0.23 -0.43 0.50 0.976 0.34 0.29 -0.25 0.93 0.354 0.57 0.29 -0.03 1.16 0.062

3D -0.07 0.19 -0.46 0.32 0.358 -0.26 0.21 -0.70 0.18 0.201 -0.71 0.27 -1.28 -0.15 0.011

PNS Y 0.10 0.22 -0.34 0.54 0.723 0.29 0.16 -0.03 0.61 0.241 -0.12 0.15 -0.44 0.19 0.674 Z 0.44 0.22 -0.02 0.89 0.060 0.49 0.26 -0.04 1.02 0.042 0.19 0.25 -0.31 0.69 0.441

3D -0.22 0.21 -0.64 0.19 0.356 -0.16 0.22 -0.61 0.30 0.372 -0.20 0.23 -0.67 0.26 0.845

ANS-PNS Yaw -0.02 0.02 -0.06 0.01 0.448 -0.02 0.02 -0.06 0.01 0.094 0.05 0.03 0.00 0.10 0.030 Pitch 0.03 0.44 -0.86 0.92 0.297 -0.14 0.29 -0.73 0.44 0.865 0.50 0.33 -0.17 1.17 0.426

Incisal

Edge

Y -0.69 0.73 -2.20 0.83 0.192 -0.61 0.52 -1.68 0.46 0.345 -1.44 0.45 -2.37 -0.52 0.009 Z -0.32 0.57 -1.51 0.88 0.423 0.52 0.35 -0.20 1.24 0.398 0.52 0.40 -0.30 1.35 0.121

3D 0.56 0.68 -0.85 1.96 0.462 -0.52 0.37 -1.29 0.25 0.389 -0.36 0.42 -1.23 0.52 0.302

CM

X 0.63 0.40 -0.19 1.44 0.141 0.64 0.42 -0.22 1.50 0.130 0.55 0.33 -0.14 1.24 0.106 Y -1.12 0.53 -2.19 -0.05 0.002 -0.19 0.46 -1.13 0.75 0.734 -2.41 0.41 -3.24 -1.58 0.000 Z 0.82 0.57 -0.34 1.98 0.004 0.91 0.43 0.03 1.79 0.060 1.29 0.42 0.44 2.13 0.003

3D 0.55 0.57 -0.61 1.70 0.172 -0.13 0.37 -0.88 0.62 0.784 -0.27 0.39 -1.06 0.51 0.473 LAI Pitch -2.37 1.86 -6.25 1.51 0.285 -0.93 1.50 -4.01 2.15 0.640 -3.13 1.22 -5.65 -0.62 0.075

LAM Pitch -3.25 1.09 -5.47 -1.02 0.001 1.72 1.65 -1.67 5.10 0.137 -7.41 1.49 -10.52 -4.31 0.000 Roll 1.02 0.88 -0.76 2.80 0.232 -0.20 0.91 -2.06 1.65 0.449 1.99 0.79 0.34 3.64 0.002

Notes:

SE. Standard Error of Mean; 95% CI. 95% confidence interval; Incisal Edge. Mid-point of the incisal edge of the permanent right upper central incisor; CM. mesio-buccal cusp tip of the permanent maxillary first molar; LAI. Long axis of the permanent right upper central incisor; LAM. Long axis of the permanent maxillary first molar; X. mesial-lateral; Y. anterior-posterior; Z superior-inferior; (+). Rightward; forward; upward; clockwise rotation; (-). Leftward; backward; downward; counterclockwise rotation.

118

Table 4. The mean differences of the dental maxillary changes relative to the maxillary superimposition in the comparison between the groups.

PHG vs. PCG PHG vs. PPHG PPHG vs. PPCG

Landmarks Coordinates Mean difference SE 95% CI P Value



Incisal

Edge

Y 0.55 0.70 -1.54 1.38 0.481 -0.63 0.44 -1.53 0.27 0.282 -0.33 0.42 -1.20 0.54 0.670

Z -0.30 0.36 -1.05 0.45 0.622 0.00 0.24 -0.49 0.49 0.822 -0.47 0.36 -1.18 0.24 0.207

3D 0.56 0.56 -0.61 1.72 0.397 -0.15 0.27 -0.70 0.39 0.395 0.12 0.29 -0.44 0.62 0.447

R CM

X 0.80 0.35 0.09 1.52 0.050 0.75 0.36 0.02 1.48 0.056 0.62 0.28 0.04 1.19 0.014

Y -0.71 0.48 -1.69 0.27 0.005 -0.08 0.42 -0.94 0.78 0.490 -1.34 0.35 -2.07 -0.62 0.000

Z 0.70 0.47 -0.26 1.66 0.000 0.56 0.35 -0.16 1.28 0.093 0.13 0.42 -0.72 0.97 0.303

3D 1.20 0.51 0.16 2.24 0.011 0.14 0.40 -0.68 0.96 0.516 0.79 0.31 0.15 1.43 0.045

L CM

X -0.55 0.30 -1.16 0.06 0.078 -0.94 0.36 -1.67 -0.21 0.106 -0.13 0.29 -0.74 0.49 0.215

Y -1.04 0.28 -1.61 -0.46 0.005 -0.54 0.54 -1.65 0.56 0.607 -1.30 0.44 -2.21 -0.38 0.001

Z 0.96 0.21 0.54 1.38 0.000 0.75 0.40 -0.07 1.57 0.042 0.80 0.36 0.03 1.56 0.005

3D 0.84 0.27 0.28 1.40 0.012 0.22 0.44 -0.68 1.12 0.685 0.86 0.37 0.08 1.63 0.003 LAI Pitch -1.80 1.99 -5.95 2.36 0.378 -2.11 1.64 -5.47 1.25 0.323 -1.98 1.41 -4.90 0.93 0.485

R LAM Pitch -2.84 1.14 -5.16 -0.52 0.003 1.71 1.60 -1.58 4.99 0.105 -6.27 1.43 -9.26 -3.28 0.000

Roll 1.22 0.88 -0.57 3.01 0.171 -0.69 1.04 -2.82 1.44 0.589 2.48 0.92 0.55 4.40 0.004

L LAM Pitch -3.16 1.09 -5.38 -0.94 0.018 -0.10 2.19 -4.58 4.38 0.449 -6.07 1.82 -9.92 -2.23 0.000

Roll 0.04 0.72 -1.42 1.49 0.987 -0.81 1.18 -3.25 1.63 0.626 0.33 1.15 -2.07 1.52 0.297 Notes: SE. Standard Error of Mean; 95% CI. 95% confidence interval; Incisal Edge. Mid-point of the incisal edge of the permanent right upper central incisor; R CM. mesio-buccal cusp tip of the right permanent maxillary first molar; L CM. mesio-buccal cusp tip of the left permanent maxillary first molar LAI. Long axis of the permanent right upper central incisor; R LAM. Long axis of the right permanent maxillary first molar; L LAM. Long axis of the left permanent maxillary first molar X. mesial-lateral; Y. anterior-posterior; Z superior-inferior; (+). Rightward; forward; upward; clockwise rotation; (-). Leftward; backward; downward; counterclockwise rotation.

119


Changes of the condyle-glenoid fossa relationship after Herbst appliance

treatment. Do they really happen?

Esse artigo será submetido para publicação no periódico The Angle Orthodontist

(Qualis A2) e ele foi formatado respeitando as normas da revista presente no link abaixo:

http://www.angle.org/page/submit?code=angf-site

120

Changes of the condyle-glenoid fossa relationship after Herbst appliance treatment. Do

they really happen?

Paula Loureiro Cheib Vileforta, Leticia Orefice Farah

b, Alexandre Moro

c, Antonio Carlos de

Oliveira Ruellasd, Bernardo Quiroga Souki

e, Lorenzo Franchi

f, James A McNamara Jr

g, Lucia

Helena Soares Cevidanesd

aPhD Student, Graduate Program in Dentistry, Pontifical Catholic University of Minas Gerais, Belo

Horizonte, Brazil. bPrivate Practice, Former resident of Orthodontics, University Positivo, Curitiba, Brazil.

cAssociate Professor, Federal University of Paraná, Graduate Program in Dentistry, University

Positivo; and Private Practice, Curitiba, Brazil. dAssociate Professor, Department of Orthodontics and Pediatric Dentistry, School of Dentistry,

University of Michigan, Ann Arbor, Mich. eAssociate Professor, Graduate Program in Dentistry, Pontifical Catholic University of Minas Gerais,

Belo Horizonte, Brazil; and Private Practice, Belo Horizonte, Brazil. fAssociate Professor, Graduate Program in Orthodontics, University of Florence, Florence, Italy.

g Thomas M. and Doris Graber Endowed Professor of Dentistry Emeritus, Department of Orthodontics

and Pediatric Dentistry, School of Dentistry; Professor Emeritus of Cell and Developmental Biology,

School of Medicine; Research Professor Emeritus, Center for Human Growth and Development, The

University of Michigan, Ann Arbor, Mich; and Private Practice, Ann Arbor, Mich.

Mailing address:

Bernardo Quiroga Souki

Av. Dom José Gaspar 500 – Coração Eucarístico

Belo Horizonte – MG – Brazil- CEP 30535-901

Telephone: +55 31 3319-4414

Email: [email protected]

121

ABSTRACT

Objective: To evaluate the spatial position of the mandibular condyles relative to their

glenoid fossae in Class II malocclusion patients after Herbst appliance (HA) treatment.

Materials and Methods: CBCT scans of 41 patients treated with cantilever HA were

compared with scans of 30 comparison individuals. Patients were grouped according to their

stage of skeletal maturation at baseline. Pubertal Herbst Group (PHG; n=24, mean age 14.5

years, CS 3-4) and Pre-pubertal Herbst Group (PPHG; n=17, mean age 9.9 years, CS 1-2)

were compared with Class II individuals in pubertal (PCG; n=12, mean age 13.9 years), and

pre-pubertal stage (PPCG; n=18, mean age 10.6 years) whose dental treatment did not include

dentofacial orthopedics. CBCT scans had been taken before treatment (T0), and after 8 to 12

months (T1). 3D surface models were constructed from scans to allow the volumetrically

superimposing of each independently glenoid fossa. Point-to-point measurements of pre-

labeled anatomic landmarks located in the condyles, and at the fossae were performed relative

to the X, Y, Z and 3D projected displacements. Qualitative assessment using semi-transparent

overlays and color-mapping were also run. Results: Relative to the glenoid fossa, condylar

position at T1 was similar to T0, in all groups (P > .05). The displacement of the condyles

within the glenoid fossae was very small (≤ 1.04 mm). Conclusion: Regardless the stage of

skeletal maturation, HA treatment did not change the original condyle-glenoid fossa

relationship.

KEYWORDS: Herbst appliance, mandibular condyles, Temporomandibular Joint, Imaging

three-dimensional

122

INTRODUCTION

Since its re-introduction in the late 1970´s1, dentoskeletal effects of the Herbst

appliance (HA) treatment have been extensively reported in the literature2–6

. The high

predictability of its clinical outcome, and the requirement of low patient`s compliance favored

the popularity of HA among orthodontists for the correction of the Class II malocclusion7.

However, an aspect on HA that still generates concern among clinicians is the hypothetical

changes in the original spatial position of the condyle within the glenoid fossa after the

mandibular therapeutic advancement, what would lead to temporomandibular (TMJ)

disorders, to dual bites, and/or to a relapse of the sagittal correction. Nevertheless, do they

really happen?

During the first two decades of life, the TMJ region and the posterior region of the

cranial base undergo three-dimensional (3D) changes associated with normal growth and

development. Significant transverse gain occurs in the TMJ, to compensate the V-shaped

growth of the mandible.8 Thus, the longitudinal spatial changes assessment of the relative

position of the condyles within their glenoid fossae should take into consideration the need for

a volumetric registration (superimpositions) of models at each glenoid fossa independently,

avoiding the bias of the transverse changes. But most studies on the condylar positional

changes following HA treatment have been performed using two-dimensional (2D)

cephalometric imaging9–13

or magnetic resonance imaging (MRI) and/or computed

tomography, but all with 2D methods.9,13–20

Unfortunately, 2D methods have low validity and

reproducibility due to magnification, distortion, and problems with the patient positioning.

Based on the assumption that the ideal situation would be, to have the condyles in their

original relationship within the glenoid fossae at the end of HA treatment, the superimposition

of two time-point scans should be performed using the volumetric best-fit of the inner contour

of the fossa. The increase in the accessibility of cone-beam computed tomography (CBCT),

and the lower radiation doses in current CBCT equipment, additional investigations on

craniofacial growth could be designed.21

Therefore, the aim of this investigation was to evaluate the condylar position relative

to the glenoid fossa after the HA treatment, comparing the spatial changes of the condyle

position of patients treated during pubertal and pre-pubertal stages of biological maturation.

123

MATERIALS AND METHODS

Sample

This retrospective clinical study was based on patient’s orthodontic records from two

universities databases (Pontifical Catholic University of Minas Gerais - Belo Horizonte,

Minas Gerais, Brazil; and Positivo University - Curitiba, Parana, Brazil). Sample size

calculation was based on the standard deviation of 0.6 mm, presented by Kinzinger, Kober

and Diedrich,18

associated with spatial position of the anterior surface of the condyles relative

to the glenoid fossa, which was the target primary outcome to be evaluated. Considering α of

5%, and β of 20%, in order to achieve a power of 80% and to detect condylar position

changes greater than 0.6 mm, it was recommended 17 individuals in each group for an effect-

size of 1.

Forty-one Class II patients with mandibular retrognatism treated effectively with HA

were allocated in HA groups. Thirty matched Class II patients served as comparison

individuals. Patients with syndromes, clefts, dentofacial deformities or temporomandibular

dysfunction were excluded from this investigation.

The skeletal maturation was assessed with the maturation of cervical vertebrae,

according to Baccetti et al.22

, and patients were grouped as pre-pubertal individuals (CS1 and

CS2) or pubertal individuals (CS3 and CS4). Patients of the PHG (pubertal Herbst group)

received the HA during the CS3 and CS4 maturation stages, while patients at PPHG (pre-

pubertal Herbst group) were treated during CS1 and CS2 maturation stages.

In PHG (n=24, mean 14.5 years old – ranging from 12 to 16 years old), and in PPHG

(n=17, mean 10.8 years old – ranging from 9 to 13 years old), the treatment duration was 8 to

12 months (mean 10 months). For all HA patients the Class II was treated and molars and

canines Class I relationship were obtained.

Comparison patients received other dental treatments that did not include dentofacial

orthopedic effects (e.g. orthodontic traction of impacted teeth, dentigerous cyst

marsupialization, prosthetic treatment or occlusal interferences in the region of the incisors

with the indication for orthodontic treatment for prior dental decompensation). The

observation period of PCG (pubertal comparison group – n=12, mean 14.1 years old – ranging

from 12 to 16 years old), and PPCG (pre-pubertal comparison group – n=18, mean 10.4 years

old – ranging from 10 to 11 years old) also ranged from 8 to 12 months (mean 10 months).

All Herbst patients were treated with a cantilever HA design with a ‘one step’

mandibular advancement (varied between 3 to 10mm, depending on the patient’s sagittal

124

discrepancy), to achieve a Class I canines and first molar relationship at the day of the HA

insertion.

Image acquisition

CBCT’s were performed using the i-Cat machine (Imaging Sciences International,

LLC, Hatfield, PA, USA) with isotropic 0.3 x 0.3 x 0.3 mm voxel. During CBCT

acquisitions, the head position had been standardized (Frankfurt plane parallel to the ground).

All patients were instructed to bite into maximum occlusal contacts. The CBCT were

performed before HA installation (T0) and after 8 to 12 months of treatment (T1). HA

patients had their T1 scans taken shortly after HA removal. Analysis of serial CBCT images

to evaluate changes between T0 and T1 included 3D analysis procedures using ITK-SNAP

(open-source software, www.itksnap.org), and 3D SLICER CMF (open-source software,

www.slicer.org). The image analysis procedures included: (1) virtual 3D surface models

construction: automatic segmentation of the anatomical structures of the patients' head were

performed using the "Intensity Segmenter" tool in 3D Slicer CMF 3.0 software; (2) head

orientation in the same Cartesian coordinate system, as described by Ruellas et al.23

(3)

manual approximation (best fit) of T0 and T1 scans using the lowest surface of right glenoid

fossa roof as reference; (4) semi-automatic and manual segmentation of the right glenoid

fossa for the construction of virtual 3D surface models of glenoid fossa that it served as

reference region for the automatic voxel based registration (Figure 1); (5) automated voxel-

based registration, of T0 and T1 scans, with the region of interest defined as the most inferior

surface of the right glenoid fossa roof, and (6) quantitative and qualitative measurements.

Methods of Measurements

Quantitative assessment of the changes of the position of the right side condyle at T1,

relative to the most inferior surface of the glenoid fossa, was performed using a 3D

volumetric registration. 3D point-to-point measurements, using ITK-SNAP for the

identification of landmarks, and the Q3DC tool of 3D Slicer for the quantification of T1

displacements in the X, Y, Z projections, and the Euclidean 3D distance were assessed. Thus,

T0 and T1 landmarks identification and pre-labeling were conducted by the same investigator,

using two independent screens, simultaneously, using the multiplanar views (sagittal, axial,

coronal) of oriented T0 grayscale scan, and registered T1 grayscale scan. Fourteen landmarks

were constructed with 0.5 mm 3D spheres (Figure 2) in each time-point scan (T0 and T1). In

the sagittal view it was marked seven spheres (Figure 2A): the most superior point of the

125

inner surface of the glenoid fossa; the most inferior point of the articular eminence; the mid-

point between spheres 1 and 2; the most posterior point of the glenoid fossa; the most superior

point of the condyle; the most anterior point of the condyle; the most posterior point of the

condyle. In the coronal view it was marked 4 spheres (Figure 2B): the most lateral point of the

glenoid fossa; the most medial point of the glenoid fossa; the most lateral point of the

condyle; the most medial point of the condyle. In the axial view it was measured the greatest

condylar diameter using the medial and lateral poles of the condyle (Figure 2C).

In order to select the sagittal slice to be used as the reference for sagittal view

measurements (named in this study as mater sagittal slice), it was identified in the axial view

the first slice that includes the full roof of the right glenoid fossa, running the mouse scroll

from top to bottom. It is a very thin bone layer. After selecting the geometric center of the

contour of the glenoid fossa roof (axial view), it was generated the mater sagittal slice (Figure

2A).

Six linear measurements from the condyle to the glenoid fossa were performed in each

time-point scan. It was also evaluated the condylar rotations (Pitch, Roll and Yaw) from T0 to

T1 (Figure 2) using the measurement #7.

Qualitative visual analysis of the displacement of the T1 condyle was performed using

semi-transparent overlays and closest-point color mapping (Figure 3). It was used 3D Slice

tools (Model maker, Model-to-model distance, and Shape Population Viewer) to calculate and

visualize the changes in the position of T1 condyle in comparison with T0 condyle, relative to

the glenoid fossa.


Data analysis was performed with the SPSS statistical software package (version 21.0;

SPSS, Chicago, IL). To determine the errors in landmark identification, and in the

displacements of the 3D spheres measurements, 30 scans were randomly selected, the models

were rebuilt, and re-measured by two investigators after a two-week interval. The random

error was measured according to Dahlberg’s formula16

and both intra and inter-observer

agreement measurements were tested using intraclass correlation coefficients (ICC), with a

confidence level of 95%. The systematic error (bias) was assessed using the paired t-test.

Some variables did not show normal distribution, and thus, the non-parametric Mann-

Whitney test was used to compare the medians. The level of significance was set at 0.05.

126

RESULTS

The ICCs were greater than 0.88 for both intra and inter-observer repeated

measurements. There were no statistically significant systematic errors between the two

measurements performed by the same operator (P > .05), and random error values varied

between 0.07 mm and 0.6 mm.

Despite the sample size calculation recommended 17 individuals in each group, it was

not possible to collect data of 17 comparison patients in the pubertal stage of maturation

(PCG). However, with the 12 individuals in that group, the post-hoc assessment computed

78.5% of achieved power (G*Power 3.1, open-source software, Dusseldorf, Germany).

Table 1 shows the descriptive data, including the median, mean and standard deviation

for the linear and rotational angular changes of the condylar position within the glenoid fossa

of treated and comparison groups, during the pubertal and pre-pubertal stages of maturation.

Changes were very small. The greatest sagittal displacement of the condyle was observed in

measurement #1 of the PPHG (0.60 mm) while the greatest vertical displacement was found

in measurement #5 of the PPHG (0.59mm).

The mean differences between groups, including the 95% confidence interval, and

standard error of the mean are shown in Table 2. The maximum displacement from T0 to T1

was found in the HPG (0.6 mm; P < .05) in measurement #3, which represents the distance

from the most posterior point of the condyle to the posterior internal surface of the glenoid

fossa. All other comparisons did not show statistically significance, and were smaller than 0.6

mm.

The difference of Pitch, Roll, and Yaw in the three comparison of the four groups

(Table 2) showed that condylar rotations after HA treatment happened. During the pubertal

period condylar pitch and roll were close to 3 degrees, while in the pre-pubertal period they

were smaller (Pitch, 1.65 degrees; Roll, 2.27 degrees). Yaw was very small, despite the stage

of skeletal maturation. None of the observed rotations presented statistical significance. In the

comparison between HA patients treated in the two stages of maturation (HPG vs. HPPG),

condylar rotations were small (≤ 1.4 degrees).

DISCUSSION

Using a novel imaging methodology, our findings corroborate previous 2D reports that

dentofacial orthopedics, using fixed mandibular advancement, in the effective treatment of

Class II malocclusion does not change the position of the condyles, relative to the glenoid

fossa. Ruf e Pancherz12

had analyzed MRI images of 15 Class II patients treated with HA for

127

7 months. They reported that “the condyle-fossa relationship was, on average unaffected by

Herbst therapy”. Kinzinger et al.17

and Kinzinger, Kober, Diedrich18

evaluated MRI’s of 20

Class II patients treated with fixed mandibular advancement device (FMA, Forestadent

Pforzheim, Germany) and found that “the improved dental occlusion was not achieved at the

price of a change to an unphysiological position in the temporomandibular joints”. The

current investigation adds to the literature a more robust sample size, with adequate statistical

power to affirm that the absence of statistical difference in the previous reports was not due to

small samples. It was also added the information that regardless the stage of maturation,

growing individuals in pre-pubertal and pubertal stages present the same result.

Despite the current knowledge on timing for an effective and efficient approach of

skeletal Class II malocclusion indicates puberty as the gold-standard,24,25

some severe Class II

patients, due to psychological problems or the increased risk of traumatic injury, need early

treatment. 26–30

Thus, we have included in our sample pre-pubertal children who had been

treated in very young age (mean age 8.6 years old). This pioneer information is important to

the clinicians, because even knowing that a significant effective condylar growth at early ages

is not likely to happen, at least an iatrogenic displacement of the condyles will not occur. Ruf

and Pancherz12

had evaluated only older patients, from 11.1 years-old to 17.6 years-old (mean

age 13.6); similar to Kinzinger and co-workers, who had also included adolescents and young

adults from 12 to 25.7 years old (mean age 15.6).18

Spatial changes of condylar position are expected during some modalities of

orthodontic treatment. Melgaço et al.31

reported a statistically significant anterior and inferior

displacements and a lateral inclination of the condyles three weeks after RME. In regard HA,

previous reports had used 2D assessments and measurements of the condylar spatial changes.

9–20 We have performed a full 3D evaluation, including the right-left (X projection), anterior-

posterior (Y projection), superior-inferior (Z), and 3D Euclidean distance measurements.

Also, it was used visual analytics tools as semi-transparent overlays of 3D models, and color

mappings, which provide a qualitative tool to comprehend what the numbers had shown.

To improve the validity of the measurements, it was performed a novel method for

regional volumetric superimposition specific for the glenoid fossa, avoiding the problems

associated with the head transversal growth, which negatively impact superimpositions based

on the mid-sagittal structures. We have decided to use only the right side, because the

mandibular advancement was similar in both sides, and it was inferred that the changes in the

right side must be similar to those in the left. In Figure 3, it is clear that condyles and rami

changed their morphology by means of bone remodeling along the HA treatment, with bone

128

apposition in the lateral surfaces (red color), and bone removal in the medial aspect (blue

color), but that the condyles kept their original position within the glenoid fossa (green color).

Bone remodeling in the superior and posterior regions of the condyle and fossa may

have been one of the factors that contributed to the maintenance of the condyle-fossa

relationship. However, with the methodology used in the present study, this cannot be

confirmed. Recent 3D studies have also suggested compensatory TMJ bone growth after HA

treatment. LeCornu et al.32

showed significant bone remodeling activity within the glenoid

fossae of HA patients. Souki et al.33

found a significant increase and change in the pattern of

bone remodeling of the condyles and mandibular ramus compared to a comparison group. It

was found that the HA patients presented a different magnitude and direction condylar growth

from comparison patients.

According to Buschang and Santos-Pinto,8 the glenoid fossa in normal growth

untreated young patients moves posterior-inferiorly along with the growth of the posterior

base of the skull, mainly by the activity of the spheno-occipital synchondrosis. In addition, the

displacement is twice greater posteriorly than inferiorly. In a period of 4 years, the

displacement reported by these authors was 3 to 4 millimeters. Therefore, displacement of the

fossa in the posterior direction is almost twice larger than the posterior condyle growth, which

would result in a posterior positioning of the mandible. Moreover, in Class II patients, the

glenoid fossa is positioned more posteriorly.8 Faced with this, it could be affirmed that the

normal growth and displacement pattern presented by the condyle and fossa occurs in an

opposite way to the direction that they need to undergo in order to maintain their relationship

as in the beginning of HA treatment. Therefore, it is suggested that the maintenance of the

condyle-fossa relationship after HA treatment is due to a combination of condyle return to the

original position due to ligament and muscle traction and a small portion of bone remodeling

with bone neoformation in the superior and posterior regions condyle, according some studies

with animals showed34,35

It is recommended additional 3D studies, with the aim to understand

the remodeling changes within the glenoid fossa and the mechanism for such a significant

rebound effect of the condyles in their glenoid fossa during HA treatment.

Differently to the current findings, Ruf and Pancherz14

used MRI and reported that the

condyles had a statistically significant anterior displacement in the glenoid fossa, immediately

after removal of the HA, in comparison with their initial position, prior to the appliance

insertion. However, one year after the appliance had been removed, the condyles returned to

its initial position.

Thus, orthodontists should not be concerned about the anterior displacement of the

129

mandibular condyles, immediately after Herbst insertion. The rebound effect is likely to

happen, and at the end of the treatment, condyles will be sited in their original position.

CONCLUSIONS

HA treatment did not change the condyle-fossa relationship, regardless the stage of

skeletal maturation. The condyles remained spatially stable relative to their glenoid fossae

after 8-12 months of treatment.

ACKNOWLEDGMENT

The authors would like to acknowledge the CAPES and FIP PUC Minas for their financial

support.

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FIGURES

Figure 1 – At the ITK-Snap software, label maps at axial (A), sagittal (B) and coronal (D)

views for the semi-automatic and manual segmentation of the right glenoid fossa for the

construction of virtual 3D surface model of glenoid fossa (C) that it served as mask (reference

region) for the automatic voxel based registration.

135

Figure 2 – 0.5 mm diameter landmarks selection at condyles and glenoid fossae, in two time

points, T0 and T1, in sagittal (A), coronal (B) and axial (C) view simultaneously allowed the

following measurements: 1 - Displacement of the most superior point of the condyle relative

to the internal superior surface of the glenoid fossa; 2 - Displacement of the most anterior

point of the condyle relative to the articular eminence; 3 - Displacement of the most posterior

point of the condyle relative to the posterior internal surface of the glenoid fossa; 4 -

Displacement of the most anterior point of the condyle relative to the anterior internal surface

of the glenoid fossa; 5 - Displacement of the most lateral point of the condyle relative to the

lateral internal surface of the glenoid fossa; 6 - Displacement of the most medial point of the

condyle relative to the medial internal portion of the glenoid fossa; 7 - Angular changes of the

most superior point of the condyle.

137

Figure 3 - A - Overlay; B and C - Color map, lateral and medial view respectively.

139

Table 1. Descriptive data and the comparison among the four groups relative to the landmarks changes. Kruskal-Wallis test.

HPG CPG HPPG CPPG P value

Landmarks Coordinates Median Mean SD Median Mean SD Median Mean SD Median Mean SD

1

X 0.00 0.00 0.01 0.00 0.00 0.01 -0.03 -0.03 0.07 0.02 0.07 0.13 0.016

Y -0.01 -0.06 0.72 0.03 0.08 0.82 0.60 0.26 1.52 -0.15 -0.09 0.42 0.247

Z -0.02 0.05 0.52 -0.09 -0.05 0.46 0.48 0.31 1.17 0.09 0.09 0.74 0.485

3D 0.07 0.12 0.57 0.15 0.24 0.59 0.63 0.29 1.54 0.06 0.06 0.70 0.674

2

X 0.00 0.00 0.07 0.00 -0.01 0.06 -0.01 0.00 0.07 0.03 0.57 2.10 0.021

Y -0.30 -0.34 0.76 -0.03 -0.08 0.72 -0.29 -0.22 1.33 -0.55 -0.65 0.92 0.301

Z 0.16 0.13 0.74 -0.44 -0.28 0.58 -0.58 -0.43 0.87 0.01 0.29 0.99 0.129

3D -0.05 -0.04 0.84 0.19 0.30 0.65 -0.37 -0.37 1.11 -0.51 -0.42 0.62 0.037

3

X -0.01 -0.02 0.07 0.00 -0.02 0.06 0.01 0.01 0.11 0.02 0.04 0.16 0.271

Y 0.29 0.32 0.62 -0.09 0.24 1.07 0.09 -0.02 1.46 -0.31 -0.11 0.90 0.245

Z 0.37 0.29 0.91 0.31 0.48 0.83 0.00 0.02 1.46 1.04 0.75 1.03 0.319

3D 0.46 0.38 0.84 -0.31 -0.22 0.66 0.08 -0.01 1.90 0.30 0.43 1.06 0.182

X 0.00 -0.02 0.04 0.00 0.02 0.05 -0.01 -0.01 0.07 0.04 0.07 0.11 0.000

4 Y -0.07 -0.07 0.59 -0.05 -0.09 0.58 -0.22 -0.20 1.26 -0.29 0.04 0.91 0.996

Z 0.24 0.22 0.99 0.17 -0.13 1.02 0.37 -0.15 1.63 0.32 0.40 1.02 0.757

3D 0.13 0.36 0.68 0.09 -0.11 1.01 -0.01 -0.48 1.66 0.14 0.36 1.08 0.289

X 0.00 0.03 0.84 -0.16 0.17 0.43 0.34 -0.12 1.77 -0.55 -0.40 0.64 0.238

5 Y 0.01 0.01 0.04 0.00 0.01 0.03 0.00 0.00 0.04 0.03 0.06 0.08 0.060

Z -0.07 0.04 0.79 -0.24 -0.38 1.03 0.59 -0.04 2.01 0.44 0.51 1.11 0.310

3D 0.26 0.21 0.76 0.18 0.18 1.20 0.89 0.27 2.53 -0.15 0.20 1.14 0.732

140

Continued

HPG CPG HPPG CPPG P value

Landmarks Coordinates Median Mean SD Median Mean SD Median Mean SD Median Mean SD

X 0.24 0.04 0.81 -0.04 0.04 0.67 -0.02 -0.23 1.00 0.07 0.41 1.32 0.648

6 Y 0.00 -0.01 0.04 0.00 -0.01 0.08 0.00 0.01 0.04 0.04 0.07 0.07 0.001

Z 0.09 0.19 0.87 0.16 0.05 0.59 0.35 0.28 1.56 0.70 1.32 2.63 0.356

3D 0.02 0.07 0.94 0.12 0.22 0.51 0.12 0.39 1.42 0.73 1.62 2.85 0.249

Pitch 2.36 2.97 4.63 1.08 -0.13 6.93 3.01 4.58 6.11 5.53 6.23 4.87 0.058

7 Roll 1.62 4.46 8.77 1.97 1.57 4.42 4.29 3.99 3.62 4.62 6.26 5.07 0.144

Yaw 0.94 0.86 3.12 1.60 1.44 1.47 1.88 2.34 1.71 3.44 3.65 1.83 0.003

Notes:

P value = Kruskal-Wallis test

Measurement 1 - Displacement of the most superior point of the condyle relative to the internal superior surface of the glenoid fossa

Measurement 2 - Displacement of the most anterior point of the condyle relative to the articular eminence

Measurement 3 - Displacement of the most posterior point of the condyle relative to the posterior internal surface of the glenoid fossa

Measurement 4 - Displacement of the most anterior point of the condyle relative to the anterior internal surface of the glenoid fossa

Measurement 5 - Displacement of the most lateral point of the condyle relative to the lateral internal surface of the glenoid fossa

Measurement 6 - Displacement of the most medial point of the condyle relative to the medial internal portion of the glenoid fossa

Measurement 7 - Angular changes of the most superior point of the condyle

141

Table 2. The mean differences in the comparison between the groups, including Standard Error of Mean, and the 95% confidence interval.

HPG vs CPG HPG vs. HPPG HPPG vs. CPPG

Measurements Coordinates Mean diff SEM 95% CI P value

Mean diff SEM 95% CI P value

Mean diff SEM 95% CI P value

X 0,00 0,00 -0,01 0,01 0,658

0,03 0,02 -0,01 0,07 0,073

-0,11 0,04 -0,18 0,03 0,058

1 Y -0,15 0,28 -0,72 0,43 0,432

-0,32 0,42 -1,20 0,56 0,167

0,34 0,40 -0,52 1,20 0,055

Z 0,10 0,17 -0,24 0,45 0,802

-0,25 0,32 -0,92 0,42 0,167

0,22 0,35 -0,50 0,93 0,329

3D -0,12 0,20 -0,54 0,30 0,730

-0,17 0,41 -1,05 0,70 0,343

0,23 0,43 -0,67 1,13 0,294

X 0,01 0,02 -0,03 0,06 0,789

0,00 0,02 -0,05 0,04 0,924

-0,57 0,50 -1,61 0,48 0,010

2 Y -0,25 0,26 -0,78 0,27 0,279

-0,11 0,37 -0,90 0,67 0,839

0,43 0,41 -0,41 1,26 0,437

Z 0,40 0,22 -0,05 0,86 0,132

0,55 0,27 0,00 1,10 0,062

-0,72 0,32 -1,38 -0,06 0,089

3D -0,34 0,25 -0,85 0,17 0,132

0,33 0,33 -0,35 1,01 0,343

0,05 0,32 -0,62 0,72 0,759

X 0,00 0,02 -0,05 0,05 0,518

-0,03 0,03 -0,09 0,04 0,249

-0,03 0,05 -0,12 0,06 0,514

3 Y 0,08 0,33 -0,63 0,79 0,198

0,34 0,40 -0,50 1,18 0,401

0,08 0,43 -0,81 0,98 0,575

Z -0,18 0,30 -0,80 0,44 0,851

0,27 0,42 -0,60 1,14 0,417

-0,73 0,45 -1,65 0,20 0,065

3D 0,60 0,25 0,09 1,12 0,022

0,39 0,52 -0,70 1,48 0,417

-0,44 0,55 -1,58 0,71 0,664

X -0,04 0,02 -0,07 0,04 0,139

-0,01 0,02 -0,05 0,03 0,785

-0,08 0,03 -0,15 0,20 0,079

4 Y 0,02 0,20 -0,40 0,44 0,875

0,13 0,35 -0,60 0,86 0,978

-0,24 0,39 -1,04 0,57 0,772

Z 0,34 0,35 -0,39 1,08 0,500

0,37 0,46 -0,60 1,33 0,695

-0,55 0,48 -1,55 0,46 0,470

3D 0,47 0,32 -0,21 1,15 0,272

0,84 0,45 -0,11 1,78 0,093

-0,84 0,50 -1,87 0,19 0,133

X -0,24 0,32 -0,03 0,04 0,265

0,15 0,49 -0,87 1,18 0,808

0,28 0,48 -0,74 1,29 0,164

5 Y 0,00 0,01 -0,03 0,02 0,900

0,01 0,01 -0,01 0,03 0,303

-0,07 0,02 -0,11 0,02 0,094

Z 0,41 0,33 -0,29 1,12 0,245

0,08 0,54 -1,06 1,23 0,756

-0,56 0,58 -1,76 0,65 0,625

3D 0,03 0,38 -0,78 0,83 0,802

-0,06 0,67 -1,48 1,36 0,357

0,06 0,70 -1,41 1,54 0,329

142

Continued

HPG vs CPG HPG vs. HPPG HPPG vs. CPPG

Measurements Coordinates Mean diff SEM 95% CI P value Mean diff SEM 95% CI P value Mean diff SEM 95% CI P value

X 0,00 0,25 -0,52 0,51 0,604 0,26 0,30 -0,36 0,89 0,372 -0,64 0,40 -1,46 0,19 0,270

6 Y -0,01 0,02 -0,06 0,04 0,285

-0,02 0,01 -0,05 0,00 0,297

-0,06 0,02 -0,10 0,02 0,098

Z 0,14 0,24 -0,35 0,64 0,660

-0,08 0,44 -1,00 0,83 0,725

-1,04 0,74 -2,55 0,47 0,294

3D -0,14 0,24 -0,62 0,34 0,683

-0,32 0,41 -1,17 0,54 0,499

-1,23 0,77 -2,81 0,34 0,262

Pitch 3,10 2,20 -1,56 7,77 0,362

-1,61 1,82 -5,38 2,15 0,357

-1,65 1,95 -5,65 2,36 0,426

7 Roll 2,89 2,14 -1,45 7,24 0,851

0,47 1,96 -3,50 4,45 0,291

-2,27 1,52 -5,37 0,82 0,311

Yaw -0,58 0,74 -2,09 0,93 0,572 -1,48 0,75 -3,01 0,04 0,116 -1,32 0,62 -2,57 0,06 0,133

Notes:

P value = Mann Whitney test

Measurement 1 - Displacement of the most superior point of the condyle relative to the internal superior surface of the glenoid fossa

Measurement 2 - Displacement of the most anterior point of the condyle relative to the articular eminence

Measurement 3 - Displacement of the most posterior point of the condyle relative to the posterior internal surface of the glenoid fossa

Measurement 4 - Displacement of the most anterior point of the condyle relative to the anterior internal surface of the glenoid fossa

Measurement 5 - Displacement of the most lateral point of the condyle relative to the lateral internal surface of the glenoid fossa

Measurement 6 - Displacement of the most medial point of the condyle relative to the medial internal portion of the glenoid fossa

143

9 CONSIDERAÇÕES FINAIS

As hipóteses nulas #1 e #2 foram rejeitadas, permanecendo as hipóteses alternativas de

que há diferenças em relação às mudanças quantitativas e qualitativas na morfologia e

posicionamento da mandíbula e maxila. Entretanto não se rejeitou a hipótese nula #3 em que

não há diferenças entre os grupos de diferentes estágios de maturação esquelética em relação

às mudanças quantitativas e qualitativas na relação côndilo-fossa mandibular.

Baseando-se na experiência clínica do corpo de pesquisadores desse estudo, e em

alguns artigos prévios sobre o tema, ao iniciarmos essa investigação existia uma expectativa

de se encontrar um maior impacto esquelético do AH, principalmente quando este fosse

utilizado durante o surto de crescimento puberal. Entretanto, pôde-se observar que, apesar da

diferença estatística estar presente em algumas variáveis testadas, os efeitos esqueléticos da

terapia com o HA foram discretos em comparação com os efeitos dento-alveolares que

tiveram grande peso na correção da má oclusão da Classe II. Mesmo assim, achamos que esse

efeito esquelético, mesmo que discreto, foi fundamental para atingirmos resultados mais

eficientes.

Diante dos resultados encontrados, podemos concluir de maneira geral que:

a) pacientes do grupo Herbst apresentaram diferente magnitude e direção de

crescimento condilar e da superfície posterior do ramo, contrastando com os

pacientes do grupo comparação. Um significativo deslocamento anterior da

mandíbula, sem rotação no sentido horário, foi observado nos pacientes que

usaram o aparelho Herbst;

b) o aparelho Herbst restringiu parcialmente o deslocamento anterior e inferior da

maxila em pacientes pré-puberais mas não em pacientes puberais. Distalização

de molares permanentes, com controle vertical, foi observado em pacientes

pré-puberais e puberais tratados;

c) o tratamento com o aparelho de Herbst não alterou a relação côndilo-fossa

mandibular, independente do estágio de maturação.

Nesse estudo procurou-se responder uma série de perguntas à respeito dos efeitos do

AH. Dividiu-se o conteúdo em três artigos. No primeiro, em que foi avaliado os efeitos

mandibulares após a instalação do AH, o acesso ao banco de dados do grupo de pacientes pré-

puberais ainda não tinha ocorrido. Logo, não foi feita a comparação desses resultados entre os

144

Grupos puberais e pré-puberais. Planeja-se rodar essa análise futuramente. Entretanto, essa

variável temporal não é uma preocupação para a comunidade ortodôntica atualmente, já que é

sabido que resultados mais eficazes e eficientes se tratando da mandíbula são alcançados

quando o tratamento ocorre durante o pico da fase puberal de crescimento.

Contrariamente, os efeitos maxilares e a relação côndilo-fossa mandibular após a

terapia com o AH, ainda não estava bem documentado na literatura se existe diferença em

relação ao estágio de maturação biológica em que o tratamento é realizado. Assim, o segundo

e terceiro artigos trazem uma contribuição acerca deste conhecimento. Encontrou-se nesse

estudo, e foi relatado pela primeira vez na literatura, que os efeitos de um aparelho de tração

extra-oral do AH são maiores em pacientes que se encontram na fase pré-puberal. E que, após

a correção eficaz da má oclusão de Classe II utilizando o aparelho Herbst, a relação côndilo-

fossa mandibular não é alterada independentemente do estágio de maturação em que o

paciente se encontra durante o tratamento.

Dentro deste projeto de estudo, teve-se também como um dos objetivos iniciais a

avaliação das mudanças na morfologia da fossa mandibular após o uso do AH. Entretanto,

devido ao enorme consumo de tempo para rodar essa análise, utilizando a metodologia

escolhida, e considerando que a doutoranda cumpriu todo o programa em 3 anos, esse

objetivo não foi possível de ser alcançado por questões temporais. Esperamos que esse estudo

possa ter continuidade com outros alunos e que essa avaliação seja feita em breve.

Ao longo do desenvolvimento deste projeto obteve-se aprovação de fomento de

pesquisa (FIP PUC Minas #2014/8545-S1) e a doutoranda foi contemplada com uma bolsa

CAPES durante sua permanência no Brasil e também uma bolsa CAPES durante sua

permanência no exterior através do Programa Doutorado-Sanduíche no Exterior (PDSE – no

88881.134753/2016-01). Durante o curso de doutorado, outras atividades foram e estão sendo

desenvolvidas paralelamente à linha de pesquisa apresentada nessa tese (ANEXOS C, D, E,

F).

145

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153

ANEXO A – 1º Parecer Consubstanciado do CEP PUC Minas

155

ANEXO B - 2º Parecer Consubstanciado do CEP PUC Minas

157

ANEXO C - Artigos científicos publicados ou aceitos em periódicos durante o curso de

Doutorado

1. CHEIB, P. L.; CEVIDANES, L. H. S.; RUELLAS, A. C. O.; FRANCHI, L.; OLIVEIRA,

D. D.; BRAGA, W. M.; SOUKI, B. Q. Displacement of the mandibular condyles immediately

after Herbst appliance insertion - 3D assessment. Turkish Journal of Orthodontics, 2016.

158

2. SOUSA, A. A.; CHEIB, P. L.; ANDRADE JUNIOR, I.; OLIVEIRA, D. D.; SOUKI, B.

Q.; CEVIDANES, L. H. S. Comparação de 2 disjuntores na expansão maxilar em pacientes

com fenda labiopalatina: relato de 2 casos. Revista da Sociedade Portuguesa de Estomatologia

e Medicina Dentária, p.116 - 124, 2016.

159

3. SOUKI, B.Q.; VILEFORT, P.L.C.; OLIVEIRA, D.D.; ANDRADE JUNIOR, I.;

RUELLAS, A.C.O.; YATABE, M.S.; NGUYEN, T.; FRANCHI, L.; McNAMARA JUNIOR,

J.A.; CEVIDANES, L.H.S. Three-dimensional skeletal mandibular changes associated with

Herbst appliance treatment. Orthodontics cranio-facial research, v. 20, p. 111-118, May 2017.

160

4. SOUKI, B.Q.; CHEIB, P.L.; ARAUJO, L.F.F.; GONTIJO, H.P.; RUELLAS, A.C.O.;

CEVIDANES, L.H.S. O uso de tomografia computadorizada por feixe cônico em ortodontia:

informações básicas para o clínico. Orthoscience, v.10 (39), p.32-50, Set 2017.

161

5. DE MATTOS, J.M.; PALOMO J.M.; RUELLAS, A.C.O.; CHEIB, P.L.; ELILIWI,

M.; SOUKI, B.Q. Three-dimensional positional assessment of glenoid fossae and mandibular

condyles in patients with Class II subdivision malocclusion. Angle Orthodontist, v. 87, p.

847-854, 2017.

162

6. OKANO, K.S.; CEVIDANES, L.H.S.; CHEIB, P.L.; RUELLAS, A.C.O.; YATABE, M.;

NGUYEN, T.; FRANCHI L.; MCNAMARA J.A.; SOUKI, B.Q. Three-dimensional

assessment of the posterior region of the cranial base following Herbst appliance treatment.

Angle Orthodontist, in press, 2018. (Aceito para publicação).

163

ANEXO D - Capítulos de livros publicados durante o curso de Doutorado

1. SOUKI, BERNARDO Q.; CEVIDANES, L. H. S.; CHEIB, P. L.; MOYSES-BRAGA,

WAGNER FERNANDO; RUELLAS, A. C. O.; FRANCHI, L.; MCNAMARA JUNIOR, J.

Three-dimensional changes in the mandible and articular fossae following Herbst appliance

therapy: A preliminary CBCT study. In: Kapila, S & Goonewardene M. (Org.).

Interdisciplinary Therapy: Using Contemporary Approaches for Complex Cases.1ed, 2016,

v.51, p. 113-134.

165

ANEXO E - Demais produções técnicas feitas durante o curso de Doutorado

1. CHEIB, PAULA L.; SOUKI, B. Q.; ARAUJO, L. F. F.

Odontodrops #1 Dicas clínicas e laboratoriais na confecção do aparelho Herbst, 2016.

(Desenvolvimento de material didático ou instrucional)

167

ANEXO F - Trabalhos publicados em anais de eventos (resumo) durante o curso de

Doutorado

1. VILLORIA, E. M.; CHEIB, P. L.; LEAO, P. L. R.; SOUZA, P. E. A.; SOUKI, B. Q.

ACOMPANHAMENTO TOMOGRÁFICO DA REGRESSÃO DE CISTO

ODONTOGÊNICO APÓS MARSUPIALIZAÇÃO: RELATO DE CASO In: X CONABRO,

2016, Porto de Galinhas. Revista ABRO. Associação Brasileira de Radiologia Odontológica,

2016. v.16. p.154 - 154

2. BARROS, H. M. P.; SOUKI, B. Q.; MATTOS, J. M.; RUELLAS, A. C. O.; PALOMO, J.

M.; CHEIB, P. L. Avaliação 3D da posição da fossa glenóide e côndilos mandibulares em

pacientes com má oclusão de Classe II subdivisão In: 33 Reunião Anual da Sociedade

Brasileira de Pesquisa Odontológica, 2016, Campinas. Brazilian Oral Research. São Paulo:

Faculdade de Odontologia da Universidade de São Paulo, 2016. v.30. p.415-415

168

3. OKANO, K. S.; SOUKI, B. Q.; CHEIB, P. L.; RUELLAS, A. C. O.; CEVIDANES, L. H.

S. Avaliação tridimensional da base posterior do crânio após o uso do aparelho Herbst In: 33

Reunião Anual da Sociedade Brasileira de Pesquisa Odontológica, 2016, Campinas.

Brazilian Oral Research. São Paulo: Faculdade de Odontologia da Universidade de São

Paulo, 2016. v.30. p.418-418

4. SANGALLI, K. L.; FARAH, L. O.; RUELLAS, A. C. O.; CHEIB, P. L.; GRANDE, I. M.

P.; SOUKI, B. Q.; MORO, A. Avaliação tridimensional do posicionamento do côndilo

mandibular após o tratamento com o aparelho Herbst In: 33 Reunião Anual da Sociedade

Brasileira de Pesquisa Odontológica, 2016, Campinas. Brazilian Oral Research. São Paulo:

Faculdade de Odontologia da Universidade de São Paulo, 2016. v.30. p.424-424

5. CHEIB, P. L.; CEVIDANES, L. H. S.; RUELLAS, A. C. O.; SOUKI, B. Q. Mudanças 3D

dentoesqueléticas mandibulares associadas ao aparelho Herbst: um estudo retrospectivo de

caso-controle. In: 33 Reunião Anual da Sociedade Brasileira de Pesquisa Odontológica, 2016,

Campinas. Brazilian Oral Research. São Paulo: Universidade de São Paulo, 2016. v.30.

p.485-485

Documents

PONTIFÍCIA UNIVERSIDADE CATÓLICA DE MINAS ...RESUMO O aparelho Herbst (AH) é um dos dispositivos mais utilizados como opção terapêutica no tratamento das más oclusões de Classe