Dental tipping and rotation immediately after surgically assisted rapid palatal expansion

The purpose of this investigation was to evaluate the effects of dental tipping and rotation immediately after surgically assisted rapid palatal expansion (SARPE). Fourteen patients (10 females, four males; mean age 25.6 years) who required a SARPE procedure were available for this study. A palatal expander appliance was cemented on four abutment teeth (first premolars and first molars) of each patient 1 week prior to surgery. Maxillary study models were taken before surgery and 2-3 weeks after full expansion (7 mm). Each model was trimmed to have the base parallel to its occlusal plane. From an occlusal view, measurements were made to determine if the abutment teeth underwent rotation from SARPE. From a postero-anterior view, the abutment teeth were examined for any tipping effect due to SARPE. The results showed that from pre- to post-expansion, the two first premolars displayed 2.32 +/- 8.29 degrees of mesiobuccal rotation (P > 0.05) and the two first molars displayed 3.09 +/- 5.89 degrees of mesiobuccal rotation (P > 0.05). Each first premolar showed 6.48 +/- 2.29 degrees of buccal tipping (P < 0.05) and each first molar 7.04 +/- 4.58 degrees of buccal tipping (P < 0.05). SARPE induced a slight mesiobuccal rotation (P > 0.05) and significant buccal tipping of the first premolars and the first molars (P < 0.05). Some overexpansion is suggested to counteract the relapse effect of buccal tipping of the posterior teeth that takes place during SARPE.