Neodymium-Doped Yttrium Aluminum Perovskite (Nd:YAP) Laser in the Elimination of Endodontic Nickel-Titanium Files Fractured in Rooted Canals (Part 2: Teeth With Significant Root Curvature).

Background In root canal treatment, fracture of nickel-titanium (Ni-Ti) instruments poses a significant challenge, particularly in teeth with complex anatomy, such as those with pronounced root curvature. A standardized and universally accepted method to address this complication remains elusive. The current study aims to assess the efficacy of neodymium-doped yttrium aluminum perovskite (Nd:YAP) laser-assisted approach in managing fractured Ni-Ti files in teeth with significant root curvature (>15 degrees). Methods Forty-seven fractured Ni-Ti files present in the curved portion of the root near the apex (the apical third of the root) greater than 15 degrees were included in this study. The Nd:YAP laser was applied using a power setting of 3 watts, delivering 300 mJ per pulse. A 200 µm fiber was employed, operating in pulsed mode at 10 Hertz with a pulse duration of 150 µs and an energy density of 955.41 J/cm² per second. These parameters had been previously validated for safety. The laser fiber was positioned in close proximity to the fractured file throughout the procedure. Success was defined as either complete removal or bypassing of the instrument, while failure included partial bypass, non-bypass, or lateral perforation. Scanning electron microscopy (SEM) was utilized in order to assess any physical modifications in the dentinal walls resulting from the laser irradiation. Energy-dispersive X-ray (EDX) spectroscopy was used to analyze the chemical composition of the dentinal canal walls after laser irradiation. Moreover, the average time of bypass was calculated when the bypass was possible. Results The overall success rate was 6.3%, in which all samples had a total bypass of the broken Ni-Ti. Of the 93.6% of failures, 74.4% experienced a lateral perforation, 10.6% a partial bypass, and 8.5% did not experience any progression or bypass. When the bypass was possible, the average time was 12.55 ± 3.26 seconds. SEM analysis revealed that the protocol results in a 26.19 µm ± 15.65 µm. EDX analysis showed that in the impact zone of irradiation, traces of 7.371 and 5.548 of Ti and Ni were shown, respectively. Conclusions The Nd:YAP laser-assisted protocol demonstrates low success rates in managing fractured Ni-Ti files in teeth with significant root curvature (>15 degrees). The study reveals that for future clinical experimentation, other procedures are necessary.