Cephalometric study of the early treatment of Class II division 1 malocclusion with the Herbst appliance: sagittal skeletal alterations

Marcus Vinicius Neiva Nunes do REGO, Guilherme THIESEN, Ernani Menezes MARCHIORO, Omar Gabriel da SILVA FILHO, Susana Maria Deon RIZZATTO

Aim: the present study aimed at evaluating the sagittal skeletal alterations after Herbst appliance treatment. Methods: the sample was comprised by in 22 subjects with Class II division 1 malocclusion, being 11 males and 11 females, with a mean age of 9.01 years (±06 months), who presented Class II facial pattern, mandibular deficiency and Class II skeletal pattern (ANB≥5º and Co-Gn – Co-Sn ≤20mm) and were consecutively treated with the Herbst appliance for a mean period of 12 months. All subjects were on the intermediate period of the mixed dentition and on the pre-pubertal stage. Evaluation was performed on lateral cephalograms taken in three different moments: T1) initial, T2) soon after removal of the appliance, T3) 2 years after treatment completion. The control group was composed by 105 subjects with skeletal Class II malocclusion not submitted to orthodontic treatment, matched as to the bone and chronological ages of the study group. Statistical analysis was performed by means of Analysis of Variance (ANOVA), complemented by the Tukey test for multiple comparisons and the Student’s t test, at a significance level of 5%. Results and Conclusion: the results revealed an not significant effect of restriction of the maxillary growth, stimulation of the mandibular growth and forward positioning of the mandible, which contributed to a significant improvement in the jaw relationship. These sagittal skeletal alterations accounted for about 41% of the correction of the Class II molar relationship and 65% of the overjet correction. At 2 years after removal of the appliance there was a tendency towards a reduction in the magnitude of the alterations achieved; however, significant improvements in the jaw relationship, overjet and molar relationship were noticeable.

Keywords: Class II malocclusion. Mandibular growth. Herbst appliance.

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