Prevalence and Association of Mandibular Three-Rooted Deciduous Second and Permanent First Molars: A Retrospective CBCT Study in Iraqi Pediatric Population

Purpose To estimate the prevalence of three-rooted mandibular deciduous second molars (3RME) and three-rooted mandibular permanent first molars (3RM6) in Iraqi children and to evaluate their association using cone-beam computed tomography (CBCT). Methods This retrospective cross-sectional study analyzed CBCT scans of Iraqi children aged 7–12 years (N = 196). Root morphology was assessed in axial, coronal, and sagittal planes. Prevalence was calculated at the patient level (presence of ≥1 affected tooth). Associations between 3RME and 3RM6 were tested using the chi-square test, and age/sex were explored as predictors using logistic regression. Intra- and inter-examiner reliability were assessed with Cohen’s kappa. Results Three-rooted morphology was identified in 3/196 children for 3RME (1.53%; 95% CI 0.52–4.40) and 10/196 children for 3RM6 (5.10%; 95% CI 2.80–9.14). A significant association was observed between 3RME and 3RM6 (χ2(4, N = 196) = 96.48, p < 0.001; Cramér’s V = 0.50). Age and sex were not significant predictors (p > 0.05). Conclusion Three-rooted mandibular molars were uncommon in this Iraqi pediatric sample; however, 3RME co-occurred significantly with 3RM6, indicating a strong association that may be clinically useful for anticipatory diagnosis and treatment planning.