Abstract: To evaluate the transverse stability of the dental arch in patients with unilateral complete cleft lip and palate after magnetic palatal expansion and fixed appliance. Methods The samples are consisted of 32 individuals with complete unilateral cleft lip and palate in the late permanent dentition who underwent with magnetic palatal expansion and fixed appliance. Maxillary arch widths and cone-beam computed tomography (CBCT) images were taken at pretreatment, posttreatment and two-year of retention. The Statistical Methods were paired t-test for dependent samples and two-way ANOVA，LSD-test were used for the mutual comparison between two groups. Results Maxillary arch widths increased significantly in arches (P<0.05), especially in first molar arch area. Arch widths decreased after two-year of retention and were not statistically significant．After orthodontic treatment the lengths of tooth roots were reduced, but only the change in mesial buccal roots of the first premolar was statistical significance (P<0.01). Conclusions Magnetic palatal expansion and fixed appliance can correct the transverse discrepancies, offering satisfactory occlusion relation, and stability in patients with complete unilateral cleft lip and palate.

Key words: cleft lip and palate, magnetic palatal expansion, arch width