Objective:The purpose of this study was to examine changes of energy output in quartz and sapphire contact tips during Er:YAG laser contact irradiation for enamel ablation and to analyze the tip surface after irradiation. Methods:The Er:YAG laser apparatus (proto-type,HOYA photonics, Japan) was employed with 10 unused straight contact tips (5 quartz and 5 sapphire tips). Er:YAG laser irradiaiton was performed on the enamel of extracted human teeth at an initial energy output of 210mJ/pulse and 20 Hz ( control panel setting: 300 mJ/pulse for quartz tip and 265 mJ/pulse for sapphire tip) in a contact mode for 60 min.. The energy output in contact tips (n=5) was measured using a power meter (Field master and LM-P10i, Coherent, USA) every 5 minutes from the beginning of irradiation. Contact surface of the tip used was observed and analyzed by Electron Probe Micro Analyzer (EPMA-8705, Shimadzu, Japan) for any alteration. Results:The energy output was 87.9% and 94.5% of the initial energy after 5 min., 84.6% and 93.2% after 10 min., 59.4% and 88.7% after 20 min., 53.4% and 76.7% after 40 min., and 49.9% and 66.0% after 60 min. with quartz tip and sapphire tip, respectively. The quartz tip revealed more rapid reduction of energy output than the sapphire tip. The unused tip had a flat surface with a sharp edge, whereas after use for contact irradiation, the tip showed an uneven surface with a rounded edge. Conclusion:It was concluded that the energy output of both types of contact tip decreased after enamel ablation in contact irradiation mode due to damage of the contact surface.

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