Soft-tissue change as a result of maxillary surgery. A preliminary study.

A retrospective investigation of soft-tissue changes following two types of maxillary surgical procedure (anterior alveolar segmental, LeForte I) in nineteen adult patients was undertaken. Several hard-tissue coordinates were correlated to each coordinate of eleven soft-tissue points by multivariate regression analysis. This new method was compared to a previously derived nonsurgical prediction method (Ricketts). The following results were observed: 1. For eight horizontal and vertical coordinates (Glh, Glv, Nah, Av, Nch, Ncv, Pnh, and Pnv), neither method was accurate. 2. For ten horizontal and vertical coordinates (Snh, Snv, Ah, Av, ULh, ULv, Stv, LLh, Bv, and Pogv), the mean prediction residuals for the multivariate method were significantly smaller than those for the modified nonsurgical method. 3. For three horizontal and vertical coordinates (LLv, Bh, and Pogh), there were no significant differences between the mean prediction residuals of both methods. Two additional cases were used to test the new method for general applicability. Visual examination reveals that the predictions for these cases are clinicallly acceptable. Only further testing can establish the true validity of the new method.