Comparison of soft-tissue changes in simultaneous maxillomandibular distraction with mandibular distraction with second-stage maxillary osteotomy.

BACKGROUND: The purpose of this study was to compare the frontal lip cant changes in common facial asymmetry (FA) cases after simultaneous maxillomandibular distraction osteogenesis (DO) and mandibular DO with maxillary orthognathic surgery.

MATERIALS AND METHODS: Retrospective analysis of FA cases at tertiary craniofacial referral was performed. Patients of either gender with all medical imaging records and pre- and post-operative (1 year) facial photographs in natural head position were included in the study. The lip cant change was assessed by the ratio of the linear dimension between affected and unaffected side labial commissures and the bi-pupillary reference line. Difference between the pre- and post-operative ratio was analyzed. Statistical analysis was performed for the outcome. P ≤0.05 was taken as significant.

RESULTS: The mean preoperative measured value of the affected side was 0.845 ± 0.036 while the postoperative value was 0.95 ± 0.032. The effective change was 0.11 ± 0.044. The postoperative ratio compared with simultaneous DO case was 0.98 ± 0.06 while that of mandibular distraction with orthognathic surgery was 0.92 ± 0.08 (P = 0.048). The mean change of the simultaneous DO case was measured as 0.114 ± 0.041 while the same for the mandibular distraction with orthognathic surgery was 0.069 ± 0.035 (P = 0.013).

DISCUSSION AND CONCLUSION: The results indicate that the simultaneous DO yields more better frontal lip cant change between both halves than the mono-DO with orthognathic surgery. The mean change is much higher in the simultaneous DO cases indicating a more effective correction and desired result. The biological reason and lip musculature mechanism behind the response in both conditions are discussed.