Nasal profile changes after maxillary impaction and advancement surgery

Purpose: The profile changes in the nasal tip and columello-labial region t hat occur after maxillary advancement and impaction surgery were measured t o test the hypothesis that a subspinal osteotomy would induce less nasal ti p change and would result in a more acute columello-labial angle than a con ventional Le Fort I-type osteotomy. Patients and Methods: The lateral cephalograms of 2 matched groups of 23 ad vancement/impact ion cases with and without subspinal osteotomy were analyz ed electronically. Results: There was no difference in nasal tip elevation and change in nasal tip projection between the 2 groups. The columello-labial angle was, on av enge, unchanged by the surgery. A linear correlation with a weak clinical r elevance could be demonstrated between nasal tip projection and maxillary a dvancement in the group that was treated without subspinal osteotomy. Such a correlation was not detected for nasal tip elevation in either of the gro ups. Palatal plane rotation had a significant influence on nasal tip projec tion but not on tip elevation in both groups. The correlation was strongest in the group treated conventionally. The multiple regression equation with maxillary advancement and rotation as predictors had a r(2) of .6071 (nasa l tip projection = 0.3 +/- 0.19 maxillary advancement + 0.18 palatal plane inclination) in this group. Conclusion: The results indicate that the advancing piriform aperture pushi ng on the alae, and not the nasal spine, is responsible for the increase in nasal tip projection. The subspinal osteotomy is not superior to the conve ntional Le Fort I-type osteotomy in regard to minimizing nasal tip changes and obtaining control over the columello-labial angle. (C) 2000 American As sociation of Oral and Association Maxillofacial Surgeons.