Cone beam computed tomography evaluation of changes in the naso-maxillary complex associated with two types of maxillary expanders.

OBJECTIVE: To test the hypothesis that there were no differences in the skeletal and dental effects of banded vs bonded expanders when evaluated using cone beam computed tomography (CBCT). MATERIALS AND METHODS: The experimental sample consisted of 23 patients: 13 (seven male, six female; mean age  =  12.6 ±1.8 years) and 10 (five male, five female; mean age  =  13.5 ± 2.1 years) treated with banded and bonded maxillary expanders, respectively. CBCT images were taken at T1 (pretreatment) and T2 (immediately after expansion) to evaluate the changes in the naso-maxillary complex. Relationships between and within groups were assessed using analysis of variance. If the results were significant, post hoc t-tests were used to determine where the significant differences occurred. RESULTS: Regardless of the appliance, the maxilla was expanded equally at the level of the canines and first and second premolars. At the level of the first molars, more dental tipping and alveolar bending were evident in the banded expander group. Both appliances equally increased the skeletal and soft tissue dimensions of the nasal cavity and maxillary sinus volume. The posterior airway volume did not significantly change with either method of expansion. CONCLUSIONS: The hypothesis was rejected. Both appliances expanded the maxilla similarly. However, in the banded group, more dental tipping and alveolar bending occurred at the level of the first molars. Maxillary expansion affected the palatal suture and demonstrated anterior and posterior skeletal widening of the nasal cavity, with corresponding soft tissue changes and increased airway volume.