Cone-beam computed tomography analysis of root canal morphology in primary mandibular molars: a retrospective study with clinical implications for pediatric endodontics.

This retrospective study aims to evaluate the root canal morphology (RCM) of mandibular primary molars using cone-beam computed tomography (CBCT) imaging. The participants were pediatric patients who received CBCT examinations at a public hospital during their dental visits. Information regarding children's age and gender was pooled from the dental records. Root canal counts, root counts, root length, and orifice distribution patterns of the eligible mandibular primary molars were analyzed by two calibrated pediatric dentists. A total of 398 mandibular primary molars were identified from 117 children. These molars had 2 to 4 roots. Two roots were observed among 88.59% of first primary molars (Ds) and 77.57% of second primary molars (Es). Three canals were most frequently observed among first mandibular primary molars, whereas the second mandibular molars predominantly had four canals. Boys had longer mesial roots than girls (p = 0.003). Molars with 5 canals presented with longer distal roots (9.08 ± 0.68) than molars with two canals (6.63 ± 0.83, adjusted p = 0.003) or three canals (7.50 ± 1.31, adjusted p = 0.049). Canal count was associated with tooth type (p < 0.001), root count (p < 0.001), and orifice distribution pattern (p < 0.001). Diverse RCMs were observed among mandibular primary molars. Clinicians should be aware that mandibular second primary molars, particularly those with ≥ 3 roots, or with trapezoidal or rectangular orifice distribution patterns, are at high risk for missed canals during pulpectomy, as they are likely to have four or more canals.