Assessment of dental arches in patients with Class II division 1 and division 2 malocclusions using 3D digital models in a Syrian sample.

AIM: (1) to evaluate the applicability of using 3D digital models in the assessment of Class II Division 1 (Cl II-1) and Class II Division 2 (Cl II-2) malocclusion in a Syrian sample, (2) to detect any significant differences between the two groups in tooth and arch widths, anterior (ABR) and overall Bolton ratios, PAR Index, and (3) to detect any gender differences in these variables. DESIGN AND SETTING: observational, cross-sectional study for descriptive and analytical purposes at the Orthodontic Dept., University of Al-Baath Hamah Dental School, Hamah, Syria. PARTICIPANTS: A disproportionate multi-stratified random sampling was employed to select 36 Cl II-1 and 36 Cl II-2 patients (female-to-male ratio was 1:1 in each group). 3D digital models (O3DM) with a dedicated programme were used to measure dental arch variables. RESULTS: Significant differences were observed between the two groups in the mesiodistal widths of some teeth but not in the dental arch widths. The prevalence of 'discrepancy cases' in Anterior Bolton Ratios (ABRs) was 33.33% and 41.67% in Cl II1 and Cl II2 groups, respectively. The mean PAR Index score was 25.36 and 20.82 for Cl II1 and Cl II2 groups, respectively (p=0.009). CONCLUSIONS: (1) 3D digital models enabled fast, accurate and reliable measurements of dental arch characteristics in patients with Class II malocclusion. (2) Insignificant differences between Cl II1 and Cl II2 patients were observed regarding Bolton's ratios and transverse arch measurements. (3) Sexual dimorphism was observed in mesiodistal tooth widths and in dental arch widths, but not in Bolton's ratios and PAR Index scores.