The Safety of Removing Fractured Nickel-Titanium Files in Root Canals Using a Nd: YAP Laser

Area of Science:

• Biomedical Engineering
• Dental Materials Science
• Endodontics

Background:

• Fractured nickel-titanium (Ni-Ti) instruments complicate endodontic treatments, with no universally accepted retrieval method.
• Previous research indicates Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) lasers can cut endodontic files.

Purpose of the Study:

• To determine safe Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) laser irradiation conditions for clinical removal of fractured Ni-Ti files.
• To evaluate temperature variations and morphological changes in dentinal walls during laser irradiation protocols.

Main Methods:

• Fifty-four extracted human teeth were divided into nine groups with varying Nd: YAP laser irradiation durations and rest periods.
• Temperature increase at the root surface was measured using a thermocouple.
• Scanning electron microscopy (SEM) assessed morphological changes in root dentinal walls post-irradiation.

Main Results:

• The safest protocol involved three 5-second irradiations with 30-second rest periods between each, combined with sodium hypochlorite irrigation.
• Continuous irradiation for 10 seconds or longer potentially risks damage to periodontal tissues.
• SEM analysis provided insights into laser-tissue interactions and potential safety margins.

Conclusions:

• A pulsed Nd: YAP laser protocol of three 5-second irradiations with 30-second rests is recommended for safe removal of fractured Ni-Ti instruments.
• Careful control of irradiation time and rest periods is crucial to prevent thermal damage to surrounding periodontal structures.