Method: Sample included 14 patients (mean age of 16.5 years) in which severe transverse maxillary deficiency (>7mm) and limited growth potential assessed by cervical vertebral maturation were observed. Patients were treated using a modified Hass expander fixed with bands adapted to the upper first premolars and first molars. Four miniscrews were inserted thorough acrylic plate to achieve skeletal anchorage. CBCT’s were taken before and after expansion. Measurements of alveolar bone thickness (BT) at the buccal and lingual aspects and evaluation of the buccolingual inclination (BLI)of the maxillary first premolars and first molars, as well as transversal distances between palatal cusp (PC) and root apex (RA) of these teeth were performed. Dependent t tests were used to compare variables pre and post-expansion. Pearson’s correlation test was used to evaluate the relationship between buccolingual inclination and transversal changes. All results were regarded as significant for P<0.05.
Result: The experiment did not affect BT of the supporting teeth. BLI of the upper first premolars remained unchanged in both sides once that transversal changes were very close increasing 4.4mm at PC level and 2.4mm at RA level. BLI of the upper first molar increased 4.2° in the right side and 3.9° in the left side associated with a greater increase of PC distance (4.4mm) when compared to RA distance (1.8mm). Pearson’s correlation test revealed no statistically significant correlation between buccolingual inclination and transversal dental changes.
Conclusion: Bone-tooth-tissue-borne expander did not affect the BT of the supporting teeth and transversal changes of upper first premolars did not affect the BLI whereas first molars were tipped bucally. Transversal dental changes were not correlated with buccolingual inclination of supporting teeth.