Study on Dental Hard Tissue Ablation by Er: YAG Laser

 Purpose: The Er: YAG laser shows excellent performance in hard tissue cutting, and is used in clinical dentistry. However, the cutting efficiency is far inferior to high-speed rotation devices, resulting in increased treatment time. Our study constructed a prototype tip with a spray-type irrigation system to improve the cutting efficiency. The prototype tip has become commercially available, and is marketed under the name “CS600F”. The present study investigated the cutting volume of human dentin, as well as the tip head wear, wear rate, and output using the CS600F.<br> Methods: Sound human molars were used as samples. A smooth dentin surface was exposed by trimming the tooth with a model trimmer, and then polishing the surface with waterproof abrasive paper up to 2000 grit. The laser was moved evenly across a 4×4 mm area on the sample surface by moving the stage 0.5 mm/s, with 10 cycles of laser irradiation. Irradiation distances were set at 0.5, 1.0, and 2.0 mm. Samples irradiated with the C600F were defined as the control group, and those irradiated with the CS600F were defined as the atomized spray group. Each sample and tip head was observed under a microscope to measure the dentin cutting volume and tip head wear volume, and the tip head wear rate was calculated (n=3). Output power from the tip head after irradiation was measured and compared with the output power from the tip head set before irradiation.<br> Results: Dentin cutting volume and tip head wear rate were significantly higher in the atomized spray group compared with the control group. However, tip head wear and output showed no significant differences between the two groups (p≧0.05).<br> Conclusion: The use of atomized spray irrigation may improve the dentin cutting volume without any change in the extent of tip wear during dentin cutting. There was no change in the tip head output after 10 cycles of irradiation in either the conventional or atomized spray irrigation systems.