Evaluation of Root Canal Anatomy of Maxillary Premolars Using Swept-Source Optical Coherence Tomography in Comparison with Dental Operating Microscope and Cone Beam Computed Tomography

Objective: This study aimed to evaluate the ability of swept-source optical coherence tomography (OCT) to detect internal anatomy of maxillary premolars in comparison with dental operating microscope (DOM) and cone beam computed tomography (CBCT). Background data: The ability of OCT to observe the pulp horn during cavity preparation and assess the remaining dentin thickness (RDT) has been demonstrated, whereas validation of OCT in comparison with other imaging techniques seems required. Methods: Ten extracted human maxillary premolars were sectioned perpendicular to the tooth axis from the occlusal surface at approximately 2mm increments. OCT and DOM were performed after each cut, and microfocus X-ray computed tomography (micro-CT; reference standard) and CBCT were conducted before sectioning and after the first and second cuts. Three examiners evaluated all images for presence of the pulp horn/pulp chamber, isthmus, lateral canals, and the number of root canals. RDT was determined from OCT, micro-CT, and CBCT images. Correlations were analyzed with Pearson's correlation coefficient. Results: OCT had a sensitivity and specificity of 0.90 and 0.80 in detecting the pulp horn/pulp chamber and 0.84 and 0.71 in detecting the isthmus, respectively. The three techniques showed strong correlations in detecting the number of root canals compared with micro-CT. OCT and DOM did not detect lateral canals. For RDT values, strong correlations were observed between micro-CT and CBCT, micro-CT and OCT, and CBCT and OCT (p<0.01 for all). Conclusions: Under the present experimental condition, OCT accurately measured RDT and detected internal tooth anatomy such as the pulp horn, isthmus, and root canals.