The output energy of quartz-fiber tips for an Er:YAG laser reduces with repeated or inappropriate handling during cavity preparation. The aim of this study was to find the best way to reuse a damaged tip for an Er:YAG laser. An amputated surface of a tip was produced by using the following: group 1 (G1): diamond disk; group 2 (G2): carborundum point; group 3 (G3): waterproof abrasive paper; group 4 (G4): ceramic scissors. An unused new tip was used as a control. The amputated tip surface was observed under a scanning microscope. G3 showed a relatively flat surface compared to G1, 2, and 4, which showed a rough and irregular surface. By analysis using a power meter, although G1 and 2 showed a large reduction of the output energy, G3 and 4 showed slightly lower energy than the control. In addition, the ablated cavity of a bovine dentine plate irradiated for 10 s with each tip was evaluated using a laser microscope. G1, 2, and 4 showed significant reduction of the ablation rate, whereas G3 showed no significant difference. These results suggest that among these four methods, waterproof abrasive paper might recover, to some extent, the tip surface morphology, output energy, and ablation rate.

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The Er:YAG laser is useful in endodontic treatment compared with conventional methods, resulting in disinfection of the root canal and elimination of smear layers including bacteria and debris. An irradiation tip for root canal treatment has been developed; it can be used to perform lateral ablation using 20% power in the forward direction and 80% power in the lateral direction. However, the relationship between energy loss and distance of the endodontic irradiation tip was unclear. The aim of this study was to evaluate irradiation energy loss with change in distance, using an Er:YAG laser apparatus (Erwin AdvErL, J. Morita, Kyoto) and irradiation tip (R200T, J. Morita, Kyoto).
The laser sensor (LMP10LP, COHERENT Inc., Portland) was placed vertically or horizontally at the irradiation tip. The irradiation energy was measured three times using a laser power meter (Field Master-GS, COHERENT Inc., Portland). The distance between the irradiation tip and sensor was varied from 1.0 to 10.0 mm. Irradiation energy was found to be inversely proportional to distance. An energy change was not clearly observed with low energy irradiation (30 mJ), however, a high energy (50 mJ and 70 mJ) setting has decrease of energy for influence distance. The lateral position was more greatly affected by the change in distance than the vertical position.
These results suggested that the energy of the new irradiation tip varied in both the vertical and horizontal directions.

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