Mandibular orthopedic advancement in different facial patterns and distinct stages of skeletal maturation

ABSTRACT The Herbst appliance can be very effective in treatment of Class II patients with mandibular retrognathism. Because of the continuous action in a full-time basis, treatment time using it normally takes from six to ten months, and is usually followed by a second phase of full fixed appliances, in order to obtain both occlusal refinement and long term stability. Despite Herbst appliance's effectiveness in the occlusal and dentoalveolar perspectives, its facial results may differ among patients with different growth patterns, as well as in distinct stages of skeletal maturation. In the current paper, two patients with different facial patterns are presented, who were treated under the same protocol, using Herbst and full fixed appliances in different skeletal maturation stages, and both dentoalveolar and facial results are compared and discussed.

RESUMO Um número significativo de pacientes que procuram o tratamento ortodôntico apresenta má oclusão de Classe II acompanhada pelo retrognatismo mandibular. Abordagens ortopédicas para avanço mandibular são comumente utilizadas enquanto houver crescimento facial remanescente e, nesses casos, o estágio de maturação esquelética deve ser avaliado para definir a melhor época de intervenção terapêutica. Após concluída a fase ortopédica, normalmente é realizada uma segunda fase ortodôntica para refinamento oclusal, com o intuito de oferecer maior estabilidade das correções em longo prazo. No presente artigo, serão discutidos os resultados do avanço mandibular ortopédico considerando-se diferentes estágios de crescimento.

Cone beam computed tomography analysis of the bony structure of the temporomandibular joint during two phase treatment with Herbst appliance / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study assessed the effects of two-phase treatment with Herbst appliance on the bony structure of the temporomandibular joint via cone beam computed tomography (CBCT) analysis.</p><p><b>METHODS</b>This study selected 15 patients exhibiting early permanent dentition and classⅡmalocclusion combined with mandibular retrusion treated by a two phase treatment (Herbst and fixed appliance). The CBCT scans of the patients were obtained at the following stages: 2 weeks before Herbst treatment (T1), at the start of treatment when the Herbst appliance was set in place (T2), immediately after removal of the Herbst appliance (T3), and immediately after removal of the edgewise appliance (T4). Three-dimensional reconstruction and related measurements were performed using InvivoDental software, and the acquired data were statistically analyzed.</p><p><b>RESULTS</b>1) CBCT showed a crescent-shaped hyperplasia at the posterior-superior border of the condyles that the outer edge was highly dense and the inner region was lowly dense in T3 in 14 patients (28 condyles). 2) In T3-T2 and T4-T1, the diameters of the anteroposterior condyles increased by 0.62 and 0.66 mm, respectively (P<0.01), and the condylar head height correspondingly increased by 0.54 and 0.53 mm (P<0.01).</p><p><b>CONCLUSIONS</b>Condylar growth remodeling occurs during Herbst treatment.
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Cephalometric evaluation of skeletal alterations induced by Herbst appliance during mixed dentition

OBJECTIVE: The present prospective clinical study was designed in order to evaluate horizontal and vertical skeletal alterations induced by the use of Herbst appliance in individuals with Class II, division 1 malocclusion during mixed dentition stage. METHODS: The sampling consisted of 15 pre-pubertal individuals (12 boys and 3 girls; initial age 9 years and 6 months), who were treated with Herbst appliance for a period of 7 months. The effects of the treatment were compared to a group of 15 individuals with Class II, division 1 malocclusion (8 boys and 7 girls, initial age averaged 9 years and 1 month), orthodontically untreated, who were followed up for a period of 12 months. Statistical analysis was performed with Student's t-test with significance level at 5%. RESULTS: It was showed that the treatment with Herbst appliance in mixed dentition stage has restricted maxilla growth. Mandibular and palatal planes have not undergone significant alteration; however, anterior and posterior facial heights have increased significantly. Facial convexity and maxillomandibular relationship were altered positively. Mandible has positioned significantly forward and its effective length increased 2.5 times more than the increase observed in control group. CONCLUSION: It was possible to conclude that Herbst appliance was able to provide satisfactory results in individuals during mixed dentition stage.

Influence of the banded Herbst appliance on dental changes in mixed dentition

OBJECTIVE: This prospective clinical study was conducted with the purpose of evaluating the influence of the banded Herbst appliance on dental changes during the early treatment of Class II malocclusion. METHOD: The sample consisted of 15 prepubertal subjects (12 boys and 3 girls, initial age: 9 years and 6 months) who were treated with the Herbst appliance. Treatment effects were compared with those of a Class II Division 1 group of 15 subjects (8 boys and 7 girls, mean initial age 9 years and 1 month), not treated orthodontically. Statistical analysis was performed using Student t-test with 5% significance level. RESULTS: The results showed that treatment with the banded Herbst appliance in the mixed dentition stage tended to upright maxillary incisors (mean: 4.14°). The maxillary molars were distalized and intruded significantly (mean 2.65 mm and 1.24 mm, respectively), the lower incisors slightly protruded anteriorly (mean 1.64 mm) and the molars showed no significant changes in the horizontal and vertical directions. Furthermore, significant improvements were noted in overbite (1.26 mm), overjet (4.8 mm) and molar relationship (12.08 mm). CONCLUSIONS: Changes in the upper dental arch were found to be greater than changes in the lower arch. Furthermore, mandibular anchorage loss was reduced due to the anchorage system used in the study.

Estudo comparativo de complicações durante o uso do aparelho de Herbst com cantiléver e com splint inferior de acrílico removível / Comparative study of complications during Herbst treatment with cantilever bite jumper and removable mandibular acrylic splint

OBJETIVO: verificar e comparar os tipos de complicações durante o tratamento com o aparelho de Herbst com cantiléver (CBJ) e com splint removível inferior. MÉTODOS: vinte e um pacientes tratados consecutivamente com o CBJ foram comparados a vinte e um pacientes tratados consecutivamente com o aparelho de Herbst com coroas de aço nos primeiros molares superiores e com splint de acrílico inferior removível. A idade inicial média para o grupo com CBJ foi de 12 anos e 3 meses, e para o grupo com splint foi de 11 anos e 3 meses. Ambos os grupos utilizaram o aparelho por um período de 12 meses. A partir da ficha clínica dos pacientes foi realizado um levantamento de ocorrências de complicações acontecidas durante o tratamento com os aparelhos de Herbst. RESULTADOS: o número total de ocorrências de complicações foi de 24 para o grupo com CBJ e de 53 para o grupo com splint. O teste de Mann-Whitney (p<0,05) demonstrou diferença significativa entre os dois tipos de tratamento em relação ao total de ocorrências de complicações durante o tratamento. A prevalência de pacientes que apresentaram alguma complicação durante o tratamento foi de 66,67 por cento para os pacientes tratados com CBJ, e de 85,71 por cento para os pacientes tratados com splint. CONCLUSÕES: o grupo com CBJ apresentou menor número de complicações durante o tratamento com o aparelho de Herbst. Em ambos os grupos, nenhum paciente apresentou individualmente um grande número de complicações. O aparelho CBJ é preferível ao modelo com splint de acrílico inferior removível, devido à economia de tempo clínico e laboratorial.

OBJECTIVE: To assess and compare the type of complications during Herbst treatment with Cantilever Bite Jumper (CBJ) and removable mandibular splint. METHODS: Twenty one consecutive Herbst patients treated with the CBJ were compared with twenty one patients consecutively treated with Herbst with stainless steel crowns on the maxillary first molars and a removable mandibular acrylic splint. The initial mean age for the CBJ group was 12 years and 3 months and for the Splint group was 11 years and 3 months. Both groups used the Herbst appliance for 12 months. Based on the patients' clinical records an occurrence survey of complications during Herbst treatment was performed. RESULTS: There were 24 complications for the CBJ and 53 for the Splint group, which were statistically different (Mann-Whitney test, p<0.05). The prevalence of patients exhibiting complications during treatment was 66.67 percent in the CBJ and 85.71 percent in the Splint group. The frequencies of complications were also statistically different between the groups. CONCLUSIONS: The CBJ exhibited a significantly smaller number of complications during Herbst appliance treatment than the removable mandibular splint. Herbst appliance with first molar crowns and a cantilever on the mandibular molars is preferable to the removable mandibular acrylic splint because of savings in clinical and laboratory time.

Avaliação in vitro da resistência à flexão de um protótipo de mini-implante desenvolvido para ancoragem do aparelho de Herbst / In vitro flexural strength evaluation of a mini-implant prototype designed for Herbst appliance anchorage

OBJETIVO: o propósito do presente estudo é avaliar o limite de resistência à flexão de um protótipo de mini-implante desenvolvido para ancoragem do aparelho de Herbst. MÉTODOS: após a realização de um cálculo do tamanho da amostra, quatro corpos de prova contendo os protótipos de mini-implantes foram submetidos a uma força de flexão por engastamento simples, utilizando-se uma máquina universal de ensaios mecânicos, sendo calculado o limite de resistência à força de flexão. RESULTADOS: após os ensaios mecânicos, os novos mini-implantes apresentaram o limite de resistência à força de flexão de 98,2kgf, que foi o menor valor encontrado. CONCLUSÃO: os protótipos de mini-implantes desenvolvidos para ancoragem do aparelho de Herbst foram capazes de suportar forças de flexão maiores do que as forças de mordida descritas na literatura.

AIM: The purpose of this study was to evaluate the limit of flexural strength of a mini-implant prototype designed for Herbst appliance anchorage. METHODS: After sample size calculation, four specimens with the new mini-implant were submitted to a single cantilever flexure test using a universal testing machine. The limit of flexural force strength was calculated. RESULTS: The mini-implant prototype showed a limit of flexural force strength of 98.2 kgf (982 N), that was the lowest value found. CONCLUSION: The mini-implant prototype designed for Herbst appliance anchorage can withstand flexural forces higher than the maximum human bite forces reported in the literature.

Tratamento ortopédico com aparelho de Herbst: ocorrem mudanças verticais no padrão de crescimento facial / Orthopedic treatment with the Herbst appliance: do vertical changes occur in the facial growth pattern

OBJETIVO: o objetivo deste estudo prospectivo de 32 adolescentes com má oclusão de Classe II, divisão 1, associada a retrognatismo mandibular, tratados com aparelho de Herbst, construído sobre bandas e coroas metálicas, foi avaliar cefalometricamente as possíveis mudanças no padrão de crescimento facial. METODOLOGIA: as telerradiografias laterais foram obtidas ao início do tratamento (T1) e imediatamente após 12 meses de tratamento com o referido aparelho ortopédico (T2). Foram utilizados o quociente de Jarabak e o VERT de Ricketts (modificado) para determinação do padrão facial em T1 e T2. RESULTADOS: utilizando o quociente de Jarabak, os resultados evidenciaram que 27 casos (84,4 por cento) apresentaram padrões hipodivergentes em T1 e permaneceram da mesma forma em T2. Cinco casos (15,6 por cento) apresentaram padrão neutro em T1 e não exibiram mudanças em T2. Quando avaliado o VERT de Ricketts (modificado), não ocorreram mudanças no padrão facial em 31 pacientes. Em apenas um caso ocorreu mudança do tipo facial. CONCLUSÃO: baseado nos resultados obtidos, pode-se concluir que, após 12 meses de tratamento com aparelho de Herbst, não ocorreram mudanças verticais no padrão de crescimento facial dos pacientes estudados.

OBJECTIVE: The aim of this prospective study was to evaluate through the exam of cephalograms the occurrence of changes in facial growth pattern. The sample was composed by 32 adolescent with Angle Class II, division 1 malocclusion and mandibular retrognathism. All patients were treated with the Herbst appliance built over bands and metal crowns. METHODOLOGY: Lateral cephalograms were taken at the beginning of treatment (T1) and immediately after 12 months of treatment with Herbst appliance (T2). Jarabak's coefficient and Ricketts' VERT (modified) were used to establish the facial pattern in T1 and T2. RESULTS: According to Jarabak's coefficient, in T1, 84.4 percent (27 cases) presented hypodiverging pattern and 15.6 percent (5 cases) presented neutral pattern. The facial growth pattern was maintained in all patients from T1 to T2. When the (modified) Ricketts' VERT was used, 31 patients showed the same growth pattern from T1 to T2. Only one patient exhibited a different pattern. CONCLUSION: Based on the results it can be concluded that, after 12 months of treatment with the Herbst appliance, there were no vertical changes in the facial growth pattern of the studied subjects.

Estudo cefalométrico das alterações dentoesqueléticas da má oclusão de Classe II, divisão 1 tratada com o aparelho de Herbst com cantiléver / Cephalometric study in patients that displayed Class II, division 1 malocclusion treated with herbst appliance

OBJETIVO: Realizou-se um estudo cefalométrico, em telerradiografias, objetivando-se determinar os efeitos no complexo craniofacial de pacientes com más oclusões de Classe II, divisão 1 submetidos ao tratamento com o aparelho de Herbst com cantiléver. METODOLOGIA: Para tanto, utilizou-se uma amostra composta por dois grupos, sendo um experimental e um controle. O grupo experimental originou-se da Faculdade de Odontologia de Bauru - USP, com 25 pacientes tratados com o aparelho ortopédico funcional e a idade inicial média de 12,01 anos. O grupo de controle, pareado cronologicamente ao grupo experimental, foi composto por pacientes não tratados ortodonticamente e/ou ortopedicamente, oriundos do arquivo de documentações denominado Burlington Growth Centre, localizado na Faculdade de Odontologia da Universidade de Toronto, Canadá. Para cada componente dos dois grupos, obtiveram-se as telerradiografias ao início (T1) e ao final (T2) do período de tratamento ou de observação, sendo traçadas manualmente e digitalizadas para um programa de cefalometria. Foram estabelecidas 33 grandezas cefalométricas. RESULTADOS E CONCLUSÕES: A comparação estatística entre o grupo experimental e o grupo controle (teste t de Student, com nível de significância p<0,05) evidenciou que a terapia corrigiu, em curto prazo, a má oclusão inicial, com grandes alterações dentoalveolares, em decorrência da perda substancial de ancoragem dentária, mesializando os molares inferiores e vestibularizando os incisivos inferiores. A terapia restringiu o desenvolvimento normal no sentido vertical dos dentes póstero-superiores, contribuindo decisivamente para a correção da relação molar de Classe II e manutenção do padrão de crescimento craniofacial dos pacientes.

OBJECTIVE: This study investigated the treatment effects on the craniofacial growth of Class II patients treated with Herbst appliance. METHODOLOGY: The sample was comprised of two groups, one experimental and one control group. The experimental group originated from Bauru Dental School, University of São Paulo. This consisted of 25 patients treated by the Herbst appliance, with an initial mean age of 12,01 years. The control group, matched by age with the experimental group, was originated from the Burlington Growth Centre, located at the Faculty of Dentistry, University of Toronto, Canada. All patients were assessed at the beginning (T1) and at the end of the treatment or observation period (T2) and 33 cephalometric variables were established. RESULTS AND CONCLUSIONS: The statistical comparison between the experimental group and the control group (Student t test) showed in short-term fashion, the correction of the initial malocclusion with pronounced dental changes (loss anchorage). The effect in inhibiting the vertical development of the maxillary first molars, essential characteristic to correct the Class II molar relationship and to maintain the craniofacial growth pattern, was shown with the therapy.

Avaliação cefalométrica dos efeitos do aparelho herbst no tratamento da deficiência mandibular na dentadura permanente / Cephalometric evaluation of the effect of the herbst appliance in the treatment of the mandibular retrognathism in the permanent dentition

OBJETIVO: o objetivo do presente estudo cefalométrico retrospectivo consistiu em investigar os efeitos induzidos pelo aparelho Herbst, complementados pela mecânica ortodôntica com aparelho Straight wire e elásticos de Classe II, na correção da má oclusão Classe II, divisão 1, Padrão II, com deficiência mandibular, na dentadura permanente. METODOLOGIA: foram traçadas telerradiografias iniciais (idade média de 12 anos e 10 meses) e finais (idade média de 14 anos e 8 meses) de 18 pacientes, 12 meninos e 6 meninas, para quantificar o comportamento de 12 grandezas cefalométricas representativas da posição sagital das bases apicais, convexidade facial, rotação mandibular e posição sagital dos incisivos superiores e inferiores. O tempo médio de tratamento foi de 22,5 meses, sendo 9,8 meses com o aparelho Herbst e 13 meses com a mecânica ortodôntica subseqüente. RESULTADOS E CONCLUSÕES: os resultados registraram: 1) ausência de influência no comportamento da maxila; 2) avanço mandibular; 3) redução na convexidade facial; 4) preservação da inclinação do plano mandibular e 5) presença de compensação dentária, sobretudo nos incisivos inferiores (vestibularização). Reitera-se, portanto, o fato de que, mesmo com aparelho ortopédico fixo, é mais previsível e mais fácil obter compensação dentária do que remodelação esquelética na correção ortopédica da deficiência mandibular.

AIM: The purpose of the current cephalometric study was to investigate the effects induced by the Herbst appliance followed by fixed orthodontic Straight wire mechanics and Class I elastics to correct a Class II division 1 malocclusion with a mandibular deficiency in the permanent dentition. MATERIAL AND METHODS: Initial (mean age of 12 years and 10 months) and final (mean age of 14 years and 8 months) cephalometric radiographs of 12 boys and 6 girls were traced to measure 12 cephalometric measurements that represented the sagittal position of the apical bases, facial convexity, mandibular rotation and sagittal position of the upper and lower incisors. Mean treatment time was 22.5 months, with 9.8 months using the Herbst appliance and 13 months with the fixed orthodontic mechanics. RESULTS AND CONCLUSIONS: The results showed: 1) no influence in the maxilla; 2) mandibular advancement; 3) reduction on the facial convexity; 4) maintenance of the mandibular plane inclination; 5) dental compensation mainly in the lower incisors (buccal tipping). Therefore, even with the Herbst fixed appliance it is more predictable and easy to obtain dental compensation than skeletal remodelling in the orthopedic correction of the mandibular deficiency.

Cephalometric roentgenographic study of Herbst appliance therapy on growing children with Class Ⅱ division 1 malocclusion and mandibular retrusion / 实用口腔医学杂志

Objective: To analyze the sagittal and vertical skeletal an d dental changes contributing to correction of Class Ⅱ division Ⅰ malocclusion and mandibular retrusion in growing children treated with Herbst appliance. Method: 27 cases of Class Ⅱ division 1 malocclusion were studied, 17 of them were treated with the domestic Herbst appliance and the other 10 case s without treatment served as the controls. Results: After 6 to 8 months (on an average of 7 months) of Herbst appliance therapy, Class II malo cclussion was corrected to Class I occlussion, overjet decreased by 7.2 mm on a n average. SNB, mandibular ramas height (Co-Go), mandibular length (Co-Pg), ma ndibular body length (Go-Pg) and the distance from Pg to OLP plane increased si gnificantly(P