OBJECTIVE: To test the hypotheses that (1) there is no difference in mandibular asymmetry between the crossbite and normal side in a unilateral crossbite group (UCG) and between the right and left sides in a bilateral crossbite group (BCG) and a control group (CG); and (2) there is no significant difference in mandibular asymmetry among crossbite groups and control group. MATERIALS AND METHODS: The cone-beam computed tomography scans of three groups were studied: (1) 15 patients (6 male, 9 female; mean age: 13.51 +/- 2.03 years) with unilateral posterior crossbite; (2) 15 patients (8 male, 7 female; mean age: 13.36 +/- 2.12 years) with bilateral posterior crossbite; and (3) 15 patients (8 male, 7 female; mean age: 13.46 +/- 1.53 years) as a control group. Fourteen parameters (eight linear, three surface, and three volumetric) were measured. Side comparisons were analyzed with paired samples t-test, and for the intergroup comparison, analysis of variance (ANOVA) and Tukey tests were used at the P < .05 level. RESULTS: According to side comparisons, no statistically significant difference was found in the UCG. There were statistically significant differences in hemimandibular (P = .008) and ramal (P = .004) volumes for the BCG and in ramal height (P = .024) and body length (P = .021) for the CG. Intergroup comparisons revealed significant differences in hemimandibular (P = .002) and body volume (P < .001) for the normal side of the UCG and left sides of the other groups, and in angular unit length (P = .025) and condylar width (P = .007) for the crossbite side of the UCG and the right sides of the other groups. CONCLUSIONS: Contrary to UCG, CG and BCG were found to have side-specific asymmetry. Skeletal components of the mandible have significant asymmetry among the crossbite groups and the CG.
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