Study on Dental Hard Tissue Ablation by Er: YAG Laser

Abstract

 Objective: Recently, the Er: YAG laser has been applied clinically and shown excellent effectiveness for the ablation of dental hard tissue. However, its ablation efficiency is significantly inferior to that of high-speed rotary ablation, and the longer treatment time has posed problems. To improve the ablation efficiency, attempts to increase the tip output and pulse repetition rate have been made, but various problems, including the effect on dental pulp, remain unresolved. Paying particular attention to the irrigation device, our study group prepared a test tip that sprays the irrigation fluid as a mist by modifying the conventional irrigation mechanism with the cooperation of J. Morita Mfg, and evaluated the ablation efficiency.
 Materials and Methods: Healthy human molar teeth, used as samples, were filed to the enamel and dentin using a model trimmer, polished using waterproof abrasive paper to #2000, and irradiated with a laser by operating the moving stage at 1 mm/s. Laser irradiation was performed by setting the distance to the sample at 0.5, 1.0, and 2.0 mm. The group in which laser irradiation was performed using C600F was regarded as a control group, and the group in which laser irradiation was performed using the test tip was regarded as the mist spray group. Each sample was examined under a laser microscope, and the cross-sectional area was calculated (n=5).
 Results: The cross-sectional area was significantly greater in the mist spray group than in the control group at an irradiation distance of 0.5 mm in enamel and at 0.5 and 1.0 mm in dentin (p<0.05).
 Conclusion: In laser ablation of dental hard tissue, spraying the irrigation fluid as a mist is considered to be effective for improving the ablation efficiency.