Edition V14N06 | Year 2009 | Editorial Article | Pages 109 to 117
Objective: to evaluate transverse changes in the maxillary dental arch and the amount of tipping of the anchoring teeth caused by the Hyrax expansion appliance in patients submitted to surgically-assisted rapid maxillary expansion (SARME), as well as the effectiveness of this surgical technique. The sample consisted of 34 pairs of plaster cast models of 17 patients, 6 male and 11 female. Methods: measurements of the changes in the vertical and transverse planes were taken in plaster cast models.. The surgical procedure performed was an osteotomy on the lateral maxillary walls without pterygoid plate involvement, osteotomy from the nasal spine to the dental midline (upper central incisors), separation of the midpalatal suture using a chisel, and nasal septum separation. Activations were initiated on the third day post-surgery, once in the morning and once at night. Results: there was a statistically significant expansion 6.03mm, 9.82mm, 8.66mm, 9.72mm and 5.67mm, in the canine, first and second pre-molar areas, respectively. When the amount of crown tipping was evaluated for the anchoring teeth, an asymmetrical buccal tipping was observed , sincethe values found for first molars were 6.89o (right) and 9.56o (left), while the values for first pre-molars were 4.74o (left) and 3.26o (right) the latter being considered statistically non-significant. Conclusions: the surgical technique applied in this study proved to be effective in achieving maxillary transverse change, resulting in dentoalveolar tipping of the appliance anchoring teeth.