Stability of mandibular incisor decompensation in orthognathic patients

This retrospective cephalometric study examined the stability of mandibular incisor decompensation following orthognathic treatment. It also studied the relationship between the mandibular incisor-mandibular plane angle (LIMnp) and the maxillary-mandibular planes angle (MMA). Two groups of 22 subjects each underwent either mandibular advancement only or bimaxillary surgery with mandibular setback. Serial radiographs of each subject were digitized. Twenty-seven Class I subjects who were part of the Leighton Growth Study served as the control. The control group showed a significant association between LIMnp and MMA. For the surgical groups, the only significant relationship between LIMnp and MMA was seen in the mandibular advancement group at debond. No definite indicator was found to suggest that the final MMA dictates the amount of mandibular incisor relapse following debond. Only the bimaxillary group showed an association between changes in LIMnp and changes in MMA during the review period.