Determine the differences in skeletal and dental maxillary expansion as evidenced by the degree of dental tipping and if this is symmetrical or not.

Sixty-two patients who were diagnosed as requiring maxillary expansion treatment were recruited over an 18-month period. Patients were randomly allocated into three groups where a total of three to four cone-beam computerized tomographies (CBCT) were obtained throughout a one-year period depending on the group allocated. Landmarks used were from the first and second molars and premolars of the maxilla. For each of the eight teeth, three landmarks were identified: the root apex, alveolar bone and pulp chamber. Statistical analysis consisted in the use of MANOVA and after significant overall effects were detected, the univariate repeated measures results were analyzed along with separate ANOVA for each variable at each of the four time points.

There was strong overall significance for time, group, and time*group. The first and second molars saw both bone- and tooth-anchored treatment groups with significantly different dental inclination than the control group. For the second premolars, only the tooth-anchored group was significantly different from control. The tooth-anchored group was also significantly different than the control group in the first premolar measurements. For the analysis of asymmetry in dental inclination, no significant time, group, or time*group effects were seen overall.

The analysis provided evidence that dental tipping does occur in the molars for both RME treatments, while the premolars showed increased tipping in the tooth-anchored, but not the bone-anchored group.