EFFECTS OF NANOSECOND PULSED ND-YAG LASER IRRADIATION ON DENTIN RESISTANCE TO ARTIFICIAL CARIES-LIKE LESIONS

Background and Objective: Previous investigations have demonstrated im proved enamel caries resistance after laser irradiation. In this study , effects of nanosecond pulsed Nd:YAG laser irradiation on crown/root dentin susceptibility to caries-like lesions were investigated. Study Design/Materials and Methods: Extracted human molar teeth were irradia ted using a Q-switched nanosecond pulsed Nd: YAG laser. All teeth exce pt controls were irradiated at: fluence, 1 or 5 J/cm(2); spot size, 3 mm; and then subjected to demineralization. Measurements of caries les ion depth using scattering light microscopy and SEM were performed. Re sults: Lesion depth measurements did not differ significantly between controls and irradiated samples (P < 0.01), but SEM results showed som e irradiation-induced alterations on crown and root dentin surfaces. I rradiated surfaces were partially melted, with sometimes narrowed or o ccluded tubules, Conclusion: No consistent caries-protective effect of Q-switched nanosecond pulsed Nd:YAG laser irradiation on crown and ro ot dentin was determined, but laser-induced morphological changes were observed. (C) 1997 Wiley-Liss, Inc.