Single-splint technique for correction of severe facial asymmetry: correlation between intraoperative maxillomandibular complex roll and restoration of mouth symmetry.

BACKGROUND: One of the most difficult problems to treat is the patient presenting with severe facial asymmetry and malocclusion whose chief complaint is the need for facial improvement. A canted intercommissural plane appears to be a major contributor to the patient's perception of facial asymmetry, but little is known about its correction. The authors adjust the intercommissural plane intraoperatively by modifying the maxillomandibular roll. However, a correlation between maxillomandibular roll and intercommissural plane change has not been demonstrated. The purpose of this study was therefore to determine whether such a correlation exists.

METHODS: A retrospective series of 18 patients with severe maxillomandibular asymmetry requiring differential maxillary impaction/extrusion (>2 mm difference in posterior maxillary vertical movement between the right and left sides) was studied. Preoperative and postoperative frontal photographs and lateral cephalometrics were studied to determine the effect of maxillomandibular complex roll on the intercommissural plane. Linear regression and statistical analysis were performed to determine the strength of the association between the two movements.

RESULTS: A linear regression could be derived from the scatterplot tracing. A Pearson correlation demonstrated a significant positive relationship between vertical maxillomandibular complex change in roll and intercommissural plane changes (r = 0.8; p = 0.000, one-tailed).

CONCLUSIONS: A correlation between maxillomandibular complex roll and intercommissural plane change has been demonstrated. This supports the usefulness of intraoperative change in maxillary roll to restore mouth symmetry in patients with severe facial asymmetry. It also identifies a major factor that can be modified to change mouth symmetry in the vertical plane during presurgical planning.