The effects of surgical expansion of the maxillary arch and its consequences for the incisor axis.

PURPOSE: Reduced transverse maxillary dental arch width may be treated either by surgically supported rapid maxillary expansion (SRME) with conservative orthodontic appliances or by means of Le Fort I osteotomy (LFIO). Both are means of transverse maxillary expansion. METHODS: Both surgical methods (SRME and LFIO) were evaluated with regard to the presurgical and postsurgical form of the maxillary dental arch and its consequences for the incisor axis by means of 32 dental casts and cephalometric analysis. RESULTS: In both groups, anterior and posterior dental arch width showed significant changes after surgery, but changes in anterior dental arch width were less significant after LFIO (p = 0.004) than after SRME (p < 0.000; t-test). Cephalometric analysis (OK1/N1) did not show any significant differences between the two surgical methods (p = 0.1266; t-test). Anterior arch length was not reduced after LFIO but significantly reduced after SRME. Thus, the ideal elliptical shape of the dental arch was lost in the SRME group, which may impede esthetic outcome of the maxillary dental arch. CONCLUSION: Le Fort I osteotomy achieving direct transverse expansion should be favored over surgically supported rapid maxillary expansion if transverse expansion does not exceed 7 mm.