Abstract: Purpose To provide more evidence for the feasibility of an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser in caries removal and adhesive restoration.Methods Thirty-six freshly extracted human molars with dentin caries were used. Each carious lesion of the isolated tooth was cut into equal-sized halves. One half was assigned to the study groups (Er:YAG laser irradiation group) and the other half to the control groups (mechanical excavation group). Five experiments were conducted to compare the characteristics of the Er:YAG laser with those of conventional mechanical devices in terms of microtensile bond strength (mTBS), microleakage, histology, micromorphology, and excavation time.Results The study groups showed higher mTBS than the control groups (n = 13, p < 0.05). The mean microleakage depth of the study groups was lower than that of the control group, but without significant difference (n = 13, p > 0.05). The study group had less remaining infected dentin tubules than the control group (n = 6, p < 0.001). Scanning electron microscope evaluation of samples in the study group showed extensive clear and exposed dentinal tubules, while smear layers were observed on dentin surface treated by a bur (n = 4). However, the study group showed longer times for caries removal than the control groups (n = 36, p < 0.05).Conclusion Although the time for caries removal is longer, the Er:YAG laser used in cavity preparation was superior to conventional mechanical devices in terms of higher mTBS and less remaining infected dentin tubules. Therefore, the Er:YAG laser is a suitable alternative clinical treatment for caries removal.

Key words: Er:YAG laser, cavity preparation, conventional mechanical devices, dental caries