Three-dimensional evaluation of facial asymmetry in association with unilateral functional crossbite in the primary, early, and late mixed dentition phases.

OBJECTIVE: To assess the degree of facial asymmetry associated with subjects with unilateral functional crossbite (CB) in the primary, early/intermediate, and late mixed dentition phases in comparison with a group of subjects without CB. SUBJECTS AND METHODS: A group of 234 white subjects, 78 with CB (42 girls and 36 boys) and 156 without CB (73 girls and 83 boys), aged 3.9-11.9, grouped according to the dentition phase, were included. Three-dimensional laser scans of the subjects' faces were used to assess facial asymmetry. For each part of the face two-way multivariate analysis of covariance was performed to assess differences among the subjects, and an independent sample t-test was used to assess the significance of the differences between data sets. RESULTS: Within all dentition phases, the subjects with CB had statistically significantly greater facial asymmetry of the whole face than the subjects without CB, with the greatest values in the lower part of the face (P < .05). In the middle part of the face a significant difference was observed in the mixed dentition phases. CONCLUSIONS: Children with unilateral functional CB exhibited a greater facial asymmetry than children without this malocclusion in all the dentition phases herein investigated. The greatest differences were seen for the lower part of the face. Further, facial asymmetry in the middle part of the face became clinically relevant in combination with the transition from primary to mixed dentition phase.