Complex root canals of maxillary second premolars are associated with the occurrence of multiple roots in maxillary first premolars: A cone-beam computed tomographic study in a Taiwanese population.

BACKGROUND/PURPOSE: Detecting two roots is generally easier than identifying complex canals within a single root using periapical films. We aimed to assess relationship between root number of permanent maxillary first premolars (PMFPs) and canal complexity in adjacent permanent maxillary second premolars (PMSPs) in a Taiwanese population using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A CBCT analysis was performed on 600 teeth (300 PMFPs and 300 PMSPs) from 150 patients. Canal morphology of PMSPs was classified according to Vertucci, bilateral symmetry was assessed, and multivariable logistic regression was applied to evaluate the association between PMFP root number and PMSP canal configuration, adjusting for sex, age, and side. RESULTS: Of PMFPs, 56 % had a single root and 44 % had multiple roots. PMSPs showed predominantly one root (96 %) and displayed mainly Type I canals (53.3 %), followed by Type III (16.7 %) and Type II (12.3 %). Complex canals were observed in 46.7 %. Males were more likely to present with multi-rooted PMFPs and complex PMSP canals (p < 0.05). Logistic regression demonstrated that multi-rooted PMFPs were significantly associated with complex PMSP canals (adjusted OR=2.507; p<0.001). Bilateral symmetry was high for both PMFProot number (77.3 %) and PMSP canal type (81.3 %). CONCLUSION: Multi-rooted PMFPs predict greater canal complexity in PMSPs. Periapical radiographs that include both premolars may provide a practical preliminary tool before CBCT, enhancing diagnostic accuracy while reducing radiation exposure.