Influence of endodontic access cavity design on root canal localization in mandibular first premolars using microscope and ultrasonic tips.

To identify the presence of a second canal in permanent mandibular first premolars treated on using conservative (CAC) and traditional endodontic access (TAC), aided by an operating microscope (OM) and ultrasonic tips. Seventy-two mandibular premolars were divided into two groups (n = 36): Group CAC and Group TAC. Canal localization was conducted initially without the OM, then with the OM, and finally with both the OM and ultrasonic tips. Statistical analyses included Cochran's Q-tests and binomial tests (α = 5%). There was no significant difference in second canal detection between CAC and TAC, whether assessed without magnification, with OM assistance, or with both OM and ultrasonic tips. Detection accuracy for the second canal significantly improved across the evaluation stages for both conservative and traditional access cavity groups, with Cochran's tests demonstrating a significant increase (CAC: p = 0.002, TAC: p = 0.049). There was no significant difference in second canal detection between CAC and TAC, whether assessed without magnification, with OM assistance, or with both OM and ultrasonic tips. Endodontists can choose the approach they prefer or that is most suitable for the clinical context, knowing that both techniques offer high reliability in detecting additional canals.