Upper and lower arch changes after Mixed Palatal Expansion protocol.

The aim of this study was to evaluate upper and lower dental changes after Mixed Palatal Expansion (MPE) treatment in growing patients with posterior single or bilateral crossbite and mild-to-moderate crowding, as compared to untreated growing subjects by dental cast analysis.A group of 24 patients (18 girls, 6 boys) was treated with Hyrax-type device and compared with an untreated matched control group at T0 (8.6 yrs. ± 2) and at T1 (10 yrs. ± 2) using dental casts. The dental cast analysis was performed on four dental bilateral landmarks, on upper and lower casts; also upper and lower arch depths were measured. The groups were compared using independent sample t-test to estimate dental changes in upper and lower arches.The MPE group showed significant upper and lower arch changes when compared with the control group. Upper intermolar, interpremolar-2nd, interpremolar-1st (P<0.001) and intercanine widths (P<0.05) showed considerable changes in the treated group, while mandibular intermolar (P<0.001), interpremolar-1st (P<0.05) and intercanine widths (P<0.01) were slightly greater in the MPE group when compared with the control group.The changes in transverse upper and lower arch dimensions were significant, when compared with those seen in the control group.