Diagnostic accuracy of a novel electronic device mode for detecting second mesiobuccal (MB2) canals in maxillary molars: an ex vivo study

This study aimed to evaluate the diagnostic accuracy of the Micro Hole Negotiator (MHN) mode for detecting second mesiobuccal (MB2) canals, using cone-beam computed tomography (CBCT) as the reference standard. In this ex vivo study, 162 extracted maxillary molars were evaluated using the MHN mode by a single operator. MHN scores were categorized as absent (0–1), possibly present (2–3), or present (4–9). Associations between MHN score categories and CBCT findings were assessed using Pearson’s chi-square and linear-by-linear association tests. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and Cohen’s kappa coefficient were calculated at predefined thresholds of ≥ 2 and ≥ 4 (α = 0.05). ROC curve analysis was performed using the full MHN score range to assess overall discriminatory ability. CBCT identified MB2 canal in 108 teeth (66.7%). The MHN mode classified 17 specimens (10.5%) as absent, 23 (14.2%) as possibly present, and 122 (75.3%) as present. MHN categories were not associated with CBCT findings (χ 2 = 2.952; p = 0.229), and no linear trend was observed (χ 2 = 0.567; p = 0.451). At the ≥ 2 cutoff, sensitivity was 87.0%, specificity 5.6%, PPV 64.8%, NPV 17.6%, and accuracy 59.9%. At ≥ 4, sensitivity was 75.0%, specificity 24.1%, PPV 66.4%, NPV 32.5%, and accuracy 58.0%. Agreement with CBCT did not exceed chance at either cutoff (κ = − 0.089 and − 0.010, respectively). In this ex vivo model, the MHN mode demonstrated limited discriminatory ability for MB2 canal detection. Its low specificity and lack of agreement beyond chance with CBCT findings do not support its use as a reliable standalone diagnostic method. Whether MHN provides additional diagnostic value when combined with other canal-detection techniques remains to be established.