Prevalence of bilateral Angle Class II and Class III molar relationships among 10- and 11-year-old pupils attending government schools in Aleppo, Syria: a cross-sectional study

Contemporary epidemiological data based specifically on bilateral first-permanent-molar relationships are scarce in Syria. This study estimated the prevalence of bilateral Angle Class II and Class III molar relationships among 10- and 11-year-old pupils attending government schools in Aleppo and explored differences by sex and age. A school-based cross-sectional survey was conducted in April 2025. Fifteen of 200 government schools were randomly selected without replacement, and all participated. All fifth- and sixth-grade pupils with recorded ages of 10 or 11 years, rounded to the nearest year, were invited. Of 1345 invitees, 1126 underwent clinical eligibility assessment; 23 were excluded because structural loss of one or more first permanent molars prevented reliable bilateral classification, leaving 1103 pupils for analysis. One examiner recorded bilateral molar relationships in maximum intercuspation. Prevalence confidence intervals (CIs) used school-level ratio residuals, the finite-population factor 1 − 15/200, and t(14) limits. Sex and age comparisons used school-cluster-robust univariable logistic models. A second dentist independently re-examined 150 pupils across all 15 schools. Bilateral Class II molar relationships were identified in 105/1103 pupils (9.52%; 95% CI, 7.29–11.75). Of these, 87 showed a Division 1-like visual incisor pattern and 18 a Division 2-like visual incisor pattern (7.89% and 1.63% of all analysed pupils; 95% CI, 5.89–9.89 and 0.93–2.33). Bilateral Class III molar relationships were identified in 47/1103 pupils (4.26%; 95% CI, 2.62–5.91). The four exploratory sex- and recorded-age-group comparisons had wide CIs for odds ratios, all including 1, and provided no clear evidence of differences ( p = 0.268–0.664). In a sensitivity analysis excluding 17 pupils with an observed orthodontic appliance, bilateral Class II molar relationships were identified in 88/1086 pupils (8.10%; 95% CI, 5.61–10.60). Three-category agreement was 94.0%; Cohen’s κ was 0.80 (school-jackknife 95% CI, 0.63–0.97). These estimates describe fifth- and sixth-grade pupils with recorded ages of 10 or 11 years attending government schools within Aleppo city whose first permanent molars were clinically assessable on both sides; they are not estimates of overall malocclusion prevalence and do not measure malocclusion severity or orthodontic treatment need.