Effect of the pterygomaxillary disjunction on surgically assisted rapid palatal expansion in context of orthodontic treatment

Objective. This retrospective study analyzed the dentoalveolar effects of pterygomaxillary disjunction (PMD) in surgically assisted rapid palatal expansion (SARPE) after orthodontic treatment. Study Design. Virtual study casts before and after orthodontic treatment involving SARPE were analyzed in 12 patients without (-) PMD and 15 patients with (+) PMD. Linear and angular measurements and maximum deviations on the alveolar ridge and hard palate were determined. Results. Dental arch widths in the first molars of the (-) and (+) PMD groups increased to 6.07 +/- 2.11 mm and 6.61 +/- 2.33 mm (P = .96) and the corresponding axial angles increased to 0.34 +/- 9.45 degrees and 2.39 +/- 9.59 degrees (P = .58), respectively. The palatal angles changed by about 0.10 +/- 11.50 degrees and 1.74 +/- 14.56 degrees (P = .75) in the (-) and (+) PMD groups and the maximum labial deviations at the alveolar ridge were 3.04 +/- 0.76 mm and 3.22 +/- 1.16 mm (P = .65) for the (-) and (+) PMD groups, respectively. Statistically significant differences were found before and after surgery (P < .04), but no significant differences were observed in PMD after orthodontic treatment. Conclusions. SARPE led to a significant transverse expansion, and the dental effects were more than the skeletal effects. We did not find a significant difference between both surgical techniques with regard to the anterior and posterior parts of the maxilla or the corresponding dentition.