Effects of Surgical and Nonsurgical Rapid Maxillary Expansion on Palatal Structures.

Aim: The aim of the present study was to compare the effects of surgical and nonsurgical rapid maxillary expansion (RME) in skeletally mature patients. Materials and methods: Surgically assisted rapid maxillary expansion (SARME) was used in 18 patients (2 males, 16 females) with a mean age of 19.90 years. Two nonsurgical RME groups were constructed to compare the expansion changes of SARME. Eighteen patients in maximum pubertal peak (12 males, 6 females) with a mean age of 13.04 years comprised the growing RME group, while the nongrowing RME (NG-RME) group consisted of 18 skeletally mature patients (1 male, 17 females) with a mean age of 16.41 years. Thirteen linear and 2 angular measurements were made on the study models taken before expansion (T0) and after 3 months of retention period (T1). Intragroup differences were evaluated with paired t test and the intergroup differences were analyzed with 1-way analysis of variance. Results: All groups showed significant transversal skeletal and dental expansion. The palatal width changes at gingival and midpalate levels were the highest in the NG-RME group (6.85 and 5.84 mm, respectively). The most molar tipping was in the NG-RME group (15.00 degrees) and the palatal vault angle showed the most increase in the SARME group (9.77 degrees). The greatest expansion at the base of palatal vault was in the SARME group (4.42 mm). Conclusions: The pattern of expansion was rotation of the maxillary halves for SARME and lateral displacement of the dentoalveolar structures for NG-RME. Patients with severe skeletal discrepancy or increased age are good candidates for SARME.