Diagnosis of Class III malocclusion in 7- to 8-year-old children--a 3D evaluation.

Objectives: The aim of this study was to characterize facial and jaw morphology of children with Class III malocclusion in early mixed dentition.

Methods: This study was conducted on 7- to 8-year-old Caucasian children, 48 children with Class III malocclusion and 91 children with normal occlusion. Surface images of faces and study casts were obtained using laser scanning. Two average facial templates were constructed for the males and females in the control group. The facial images were superimposed on the corresponding average templates. Facial parameters, palatal volumes, and gingival surface areas were measured and group differences were quantified. The analysis of variance was used for statistical evaluation of the measured parameters.

Results: The results revealed shorter lower face height (P < 0.001), concave facial profile (P < 0.001), retruded maxilla (P < 0.001), protruded mandible (P < 0.001), retrusive mid-face restricted area (P < 0.001), reduced gingival surface area of the maxilla (P = 0.013), and reduced maxilla/mandible gingival surface area ratio (P < 0.001) in the Class III group compared to the control group. There were no differences between the groups in upper face height, restricted areas of the upper and lower face, palatal volume, and gingival surface area of the mandible (P > 0.05).

Limitations: Regardless of the fact that the prevalence of Class III malocclusion is rather small, the sample size could be larger.

Conclusions: Class III subjects show clinically relevant facial and jaws characteristics in pre-pubertal growth period. A comprehensive diagnosis should include transverse dimension analysis.