In Vitro Evaluation of a Novel Root Canal Endoscope for Visualizing the Apex of Curved Root Canal Models and an Extracted Tooth

Abstract

Introduction: In straight root canals, intraradicular structures around the root canal orifice and apical foramen can be visualized with a dental operating microscope and commercially available root canal endoscopes. However, the root apex area, including the apical foramen, in a curved root canal cannot be visualized using these devices. In the present study, the potential of a newly developed root canal endoscope implementing an image fiber was examined in 3 types of root canal models and extracted teeth.

Methods: A straight and 2 curved (10° and 30°) resin block models were prepared. A resolution chart was set at the outer surface of the apical foramen in each model. Using the microscope and the endoscope, the resolution chart was observed, and the captured images were analyzed quantitatively. Additionally, fracture lines in 20 extracted teeth were observed with both devices.

Results: With the dental operating microscope, a resolution chart line was clearly observed in the straight canal model with 18.0 line pairs/mm resolution and an observing capability of 0.16 at 40 × magnification but not in the curved root canal models. With the root canal endoscope, resolution charts in all types of root canal models were visualized, and the resolution and observing capability were 16.0 line pairs/mm and 0.053, respectively. Fracture lines and the apical foramen of the extracted teeth were observed more clearly with the endoscope than the microscope.

Conclusions: The newly developed root canal endoscope using an image fiber is useful for accurate visualization of the apex area of curved root canals.

Keywords: Apical foramen; curved root canal; root canal endoscope; visibility.