Endodontic applications of endoscopic optical coherence tomography

Objectives: The purpose of this study was to evaluate the ability of an endoscopic optical coherence tomography (OCT) system to accurately image the root canal walls and anatomy, diagnose vertical root fractures (VRF) and assess its potential as both an in-vitro tool for endodontic research and a clinical aid during endodontic therapy. Methods: Human mandibular premolars (n=30) were prepared to file size 50 following routine endodontic procedures and randomly divided into 3 groups of 10 teeth each. Group 1 was additionally treated with EDTA and ultrasonic irrigation. Teeth from groups 1 and 2 were fractured with a finger spreader, and the presence of a fracture line was demonstrated microscopically. Group 3 teeth served as controls and were not subjected to any force. All teeth were pooled and scanned with an OCT rotating fiber. The resulting video files were blindly interpreted by 2 observers. Group 3 teeth were then sectioned at 3, 6 and 9mm from the apex and viewed through a light microscope. Histological sections were compared with the corresponding OCT output. Results: No fractures were detected in group 3. The overall sensitivity for detection of VRF with OCT was 93% for group 1 and 84% group 2, whereas the specificity was 95% for group 1 and 96% for group 2. The inter- and intra-observers agreement were high (Cohen's kappa=0.9), demonstrating a high reproducibility and reliability of the test. OCT scans accurately demonstrated various intra-canal anatomical and iatrogenic features. Conclusion: endoscopic OCT represents a nondestructive technique for imaging the root canal walls and detection of VRF without using ionizing radiation and could be applied in-vivo once an appropriate probe becomes available. Scientific evidence could be enhanced using this imaging method to assess the cleaning efficiency of different protocols and preparation techniques.