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Herbst treatment of Class II division 1 malocclusions in retrognathic and prognathic facial types.

OBJECTIVE
The aim of this retrospective pilot study was to analyze and compare the short-term and long-term changes of Herbst treatment in Class II division 1 subjects of the retrognathic and prognathic facial type.


MATERIALS AND METHODS
The subject material comprised 10 retrognathic (mean SNA = 74.5 degrees, SNB = 70.4 degrees, ML/NSL = 41.1 degrees) and 16 prognathic (mean SNA = 86.7 degrees, SNB = 81.5 degrees, ML/NSL = 25.1 degrees) Class II division 1 subjects treated with the Herbst appliance for an average period of 7 months. Lateral head films from before (T1), immediately after (T2), 12 months after (T3), and 39 months after (T4) Herbst treatment were analyzed with the SO-analysis (analysis of changes in sagittal occlusion) and standard cephalometrics.


RESULTS
During the treatment period (T2-T1) the two facial type groups showed similar favorable changes for all variables. During the posttreatment periods of 12 months (T3-T2) and 39 months (T4-T2) recovering changes occurred. In the long-term, a tendency of more unfavorable growth changes was stronger (not significant) for retrognathic subjects than for prognathic subjects.


CONCLUSION
On a long-term basis, retrognathic subjects are prone to exhibit more unfavorable mandibular growth changes than prognathic subjects and, thus, might exhibit a greater risk for an occlusal relapse when a stable Class I occlusion is not attained after treatment.