Computer-Controlled CO2 Laser Ablation System for Cone-beam Computed Tomography and Digital Image Guided Endodontic Access: A Pilot Study

Introduction: Ideal endodontic access provides unobstructed entry to the pulp chamber and visualization of the canal orifices while preserving the maximum amount of tooth structure. The aim of this study was to implement the use of lasers to accurately and predictably access teeth to follow the principles of minimally invasive endodontics. Methods: Traditional, conservative, ultraconservative, bridge, truss, and orifice-directed accesses were performed. A computer-controlled 9.3-mu m CO2 laser ablation system was assembled and coupled with custom software capable of combining cone-beam computed tomographic (CBCT) volumetric data with spatially calibrated digital images of teeth to provide an augmented reality environment for designing and preparing endodontic accesses. Twenty (N = 20) sound posterior teeth with fully developed root canal systems were imaged with CBCT scans and accessed via laser ablation in vitro. Results: All 20 (20/20) teeth were successfully accessed without iatrogenic errors. Volumetric renderings from post-access CBCT scans were used to verify the access and determine accuracy qualitatively. The volumetric measurements of hard tissue removed were as follows: traditional = 39.41 mm(3), conservative = 9.76 mm(3), ultraconservative = 7.1 mm(3), bridge = 11.53 mm(3), truss = 19.21 mm(3), and orifice directed = 16.86 mm(3). Conclusions: Digital image guidance based on feature recognition and registration with CBCT data is a viable method to address the challenge of dynamic navigation for accessing the pulp chamber. Modern lasers with high pulse repetition rates integrated with computer-controlled scanning systems are suitable for the efficient cutting of dental hard tissues.