Dentoalveolar Changes in the Premolar Region After Two Maxillary Expansion Protocols

OBJECTIVES: To evaluate the dentoalveolar effects on the upper first premolars after two maxillary expansion protocols-rapid maxillary expansion (RME) and alternate rapid maxillary expansion and constriction (Alt-RAMEC)-before and 6 months after treatment. MATERIALS AND METHODS: Cone-Beam Computed Tomography (CBCT) images of 20 patients who underwent maxillary expansion with the Hyrax appliance under two activation protocols were evaluated. Dental and alveolar measurements at the premolar region (tooth length, alveolar bone level and thickness) were measured before (T1) and after expansion (T2). Intra- and inter-examiner reliability was determined using Intraclass Correlation Coefficients. Statistical analyses included the Shapiro-Wilk test and Student's t-tests for paired and independent samples. Statistical significance was set at 5%. RESULTS: A significant increase in interpremolar distances was observed, both in the radicular and coronal levels (4.29 mm and 4.97 mm), with greater coronal than root distance. This was more evident in the Alt-RAMEC group. Alveolar thickness showed an average reduction of 0.54 mm after expansion. CONCLUSIONS: The expansion effects of the two protocols were similar in the premolar region, resulting in a reduction in alveolar thickness. A tendency for greater tooth inclination and root reduction was observed after the Alt-RAMEC protocol. TRIAL REGISTRATION: IRB: 42856915.1.0000.5336.