Maxillary Expansion and Stability in Cleft and Non-Cleft Patients

Skeletal expansion of the maxilla is often required prior to alveolar bone grafting in cleft lip and palate patients and in non-cleft patients when posterior crossbites are present due to maxillary constriction. Objectives: The purpose of this study was to evaluate and compare the molar movements resulting from rapid maxillary expansion between cleft and non-cleft patients. Methods: Study models of 13 cleft (4 cleft lip, 9 cleft lip and palate – 10 left-sided, 2 right-sided, one bilateral) patients and 10 non-cleft patients who underwent rapid maxillary expansion successfully as a separate first phase of orthodontic treatment were used. Models were made before expansion and before a second phase of treatment, with a period of retention in between. At each timepoint, intermolar width and molar buccal-lingual angulations were measured and the changes between timepoints were calculated. Results: There were no significant differences between groups in molar width or molar angulations before or after expansion (P>0.05). Both cleft (4.8±4.3 mm; P=0.002) and non-cleft (5.4±3.8 mm; P=0.001) patients experienced significant increases in molar width as a result of expansion, but these increases were not different between groups (P=0.72). Left molars tipped buccally significantly more in the cleft patients than non-cleft patients (2.8±6.0° flaring vs 3.1±4.3° uprighting; P=0.02) but there were no differences in the right molar angulation change between groups (P=0.99). After the retention period, one patient in each group had return of a crossbite that required correction during the second phase of treatment. Conclusion: Comparison of cleft and non-cleft patients undergoing rapid maxillary expansion showed little difference in the amount and success of expansion achieved but suggested that differences in the amount and direction of molar angulation change (tipping) may occur.