Dentoskeletal treatment effects produced by the Herbst appliance in the mixed dentition

Marcio Rodrigues de ALMEIDA, José Fernando Castanha HENRIQUES, Renato Rodrigues de ALMEIDA, Weber URSI, Renata Rodrigues de ALMEIDA-PEDRIN, James A. MCNAMARA JR.

Aim: the purpose of this prospective clinical investigation was to evaluate the dentoalveolar and skeletal cephalometric changes produced by the Herbst appliance in individuals with a Class II division 1 malocclusion and who were in the mixed dentition. Methods: thirty patients (15 males, 15 females) treated with the Herbst appliance for a period of 12 months had an initial mean age of 9 years 10 months. For comparison, the records of a historical control group of 30 untreated Class II children (15 males, 15 females) with an initial mean age of 9 years 8 months and who were followed without treatment for a period of 12 months was established. Lateral cephalometric headfilms were available at the beginning and the end of the treatment/observation period. Results and Conclusions: the results of this study indicated that the treatment effects produced in mixed dentition patients were primarily dentoalveolar in nature. The mandibular incisors were tipped labially and the maxillary incisors were retruded; there also was a significant increase in mandibular posterior dentoalveolar height and a restriction in the vertical development of the maxillary molars. There was no difference in the forward growth of the maxilla between the two groups. Herbst treatment, however, produced a modest but statistically significant increase in total mandibular length in comparison to controls, an amount, however, that was less that that observed in adolescent patients treated with a similar Herbst protocol. There were no statistically significant differences in craniofacial growth direction between the Herbst and control groups. Overjet correction averaging 5.4mm was due to 22% skeletal and 78% dental changes. Class II molar correction averaging 4.4mm was due to 27% skeletal and 73% dental changes.

Keywords: Herbst appliance. Orthodontic treatment. Treatment effects. Cephalometrics.

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