Assessment of the Prevalence of Middle Mesial Canal in Mandibular First Molar: A Multinational Cross-sectional Study with Meta-analysis

Background: An additional canal found in the mandibular first molar (M1M) is the middle mesial canal (MMC), which is often missed during root canal treatment. In this study, the prevalence of MMC in M1M on cone-beam computed tomography (CBCT) images was evaluated in 15 countries, along with the effect of some demographic factors on its prevalence. Methods: Deidentified CBCT images were scanned retrospectively, and the ones including bilateral M1Ms were included in the study. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating three planes (coronal, sagittal, and axial) after a 3-dimensional alignment of the long axis of the root(s). The presence of an MMC in M1Ms (yes/no) was identified and recorded. Results: In total, 6304 CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries (P .05) or between genders (odds ratio= 1.07, 95% CI: 0.91, 1.27; P > .05). As for the age groups, no significant differences were found (P > .05). Conclusions: The prevalence of MMC varies by ethnicity, but it is generally estimated at 7% worldwide. Physicians must pay close attention to the presence of MMC in M1M, especially for opposite M1Ms, due to the prevalence of MMC being significantly bilateral

Repair versus replacement of defective direct dental restorations:A multinational cross-sectional study with meta-analysis

Objectives: When dental practitioners encounter a defective restoration, they are faced with a crucial decision whether to repair or replace it. This study aims to explore international preferences for repair procedures and the clinical steps taken during the repair process. Method: An 11-question survey was distributed to dentists across 21 countries via different platforms. The survey comprised two sections: the first included five questions aimed at gathering demographic information, while the second consisted of six questions focusing on participants' practices related to the repair of composite or amalgam restorations A meta-analysis was employed to ascertain the pooled odds ratio of repairing versus replacement. The statistical analysis was carried out using the RevMan 5.3 program and forest plots were generated using the same program to visualize the results. Results: The survey was completed by 3680 dental practitioners. The results indicated a strong tendency to repair defective composite restorations (OR: 14.23; 95 % CI: 7.40, 27.35, p &lt; 0.001). In terms of amalgam, there was a significant tendency to replace the restorations (OR: 0.19; 95 % CI: 0.12, 0.30, p &lt; 0.001). When repairing restorations, the most common protocols were etching with orthophosphoric acid and creating an enamel bevel, regardless of the restorative material used. Conclusion: The findings of this study indicate that there exists a knowledge gap among dental practitioners regarding restoration repair. It is imperative that dental practitioners receive proper education and training on restoration repair, to ensure the usage of adequate protocols and restoration survival. Clinical significance: A significant portion of dental practitioners lack the necessary knowledge and education required for the repair of restorations. Therefore, it is imperative to establish guidelines aimed at enhancing the management of defective restorations, along with protocols for clinical interventions. This includes the incorporation of proper courses in undergraduate, graduate, and continuing education programs.</p