SUBSURFACE MORPHOLOGIC CHANGES OF ND-YAG LASER-ETCHED ENAMEL

Background and Objective: Etching the enamel surface with a Nd:YAG den tal laser produces impact craters with cavities, micropores, and micro fissures. This in vitro SEM study examined laser-etched enamel to dete rmine the pattern and extent of subsurface changes. Study Design/Mater ials and Methods: The facial surface of 10 maxillary central incisor t eeth were coated with a black initiator and laser-etched with a pulsed Nd:YAG laser (1.06 lambda, 75 mJ, 15 Hz, 320 mu m fiber, 94 J/cm(2) f luence). The facial surface of five teeth were plastic-embedded under a low vacuum, then demineralized in 10% formic acid. The other teeth w ere split incisoapically. All samples were prepared for SEM. Results: Examination of the plastic impressions showed a delicate interlacing p attern of thin partitions and small knob-like expansions. Examination of the split teeth showed the penetration of microfissures into the en amel estimated at 10 mu m. Conclusion: These subsurface alterations ma y provide space for the infiltration and mechanical retention of denta l resin. (C) 1997 Wiley-Liss, Inc.