Aim: The purpose of this study was to determine which factors were predictive of maxillofacial morphological change and growth in Class III patients in whom, although early treatment had been carried out during the mixed dentition period, orthognathic surgery was judged necessary on commencement of corrective orthodontic treatment.
Subjects and Methods: The surgical group consisted of 15 Class III patients requiring orthognathic surgery in who orthodontic treatment had been commenced during the mixed dentition period. The control group consisted of 16 Class III patients requiring corrective orthodontic treatment alone during the same period. Lateral cephalograms were obtained at 3 time points: at taking of initial record of mixed dentition period (T1), at complete eruption of permanent dentition (T2) and at beginning of pre-surgical orthodontic treatment (T3). Twenty-seven measurements were analyzed: 10 linear measurements, 9 angular measurements and 8 Ricketts’s Internal structure measurements. Maxillofacial morphology at T1, T2 and T3 and growth aspects between each period were evaluated statistically.
Results: Go-Me and Corpus Length in the surgical group were significantly larger than those in the control group at T1, but Mand arc was significantly smaller. Wits,Ar-Pog, ANB, Gonial angle and AB-Mand angle also showed a significant difference at T2. Ar-Go , N-perpendicular to Pog and SNB also showed a significant difference at T3.
Conclusion: Our findings indicate that size, shape and growth potential of the mandible must be taken into consideration in treatment planning for Class III during the mixed dentition period.