Comparative evaluation of root canal morphology in mandibular first premolars with deep radicular grooves using direct vision, dental operating microscope, 2D radiographic visualisation and micro-computed tomography

Objectives: The objective of this study was to evaluate the effectiveness of clinically applicable diagnostic methods such as Direct Vision (DV), Dental Operating Microscope (DOM), and two-dimensional (2D) radiographs in detecting canal orifices and root canal configurations in mandibular first premolars with deep radicular grooves. The study also aimed to compare these methods with micro-computed tomography (micro-CT) to better understand their diagnostic capabilities and to assess the applicability of the Ahmed et al. (2017) classification system across different imaging modalities. Methods: A total of 133 mandibular first premolars with deep radicular grooves were scanned using micro-CT. After scanning, two examiners, blinded to micro-CT results, accessed and examined the root canal orifices of the study samples under DV, and DOM. Further evaluation of the root canal configurations was undertaken using exploration and 2D radiographic images. A second round of relocation of canals was undertaken if the radiographic view showed the presence of a missed canal. The data were then compared with the original reconstructed micro-CT images. Descriptive statistical analysis, Kappa and chi-square tests were performed to compare between methods and examiners, and the p-value was set at 0.05. Results: Except for three teeth, all samples exhibited multiple canals. Micro-CT data revealed a wide range of root canal configurations, with the most common being 1MFP1-2 (19.54%), followed by 1MFP1-2-3 (15.78%), 1MFP1-2-3-2 (5.26%), and both 1MFP1-2-4 and 1MFP1-2-1 configurations, each at 4.51%. For both examiners, using the DOM resulted in detection of more canal orifices compared to DV (p