EFFECTS OF A 532NM Q-SWITCHED NANOSECOND PULSED-LASER ON DENTIN

The purpose of this study was to determine whether a nanosecond-pulsed , frequency-doubled Nd:YAG laser emitting at 532 nm can be used as an alternative to mechanical methods of root canal treatment or as an adj unct to conventional endodontic preparation. Laser parameters whose th ermal effects did not exceed safety thresholds for adjacent periodonta l tissues were selected in a preliminary study. In 27 extracted human teeth, root canals were irradiated for 30 to 60 s at fluences of 2 to 2.2 J/cm2, and 10 Hz. Samples were observed using SEM. Laser irradiati on could achieve smear layer removal after minimal manual preparation. However, results were inhomogeneous, and at higher energy densities t hermal damage was observed, especially in the fully manually prepared samples. Nanosecond-pulsed irradiation at 532 nm can achieve complete smear layer removal. However, mechanisms must be developed to monitor laser effects and avoid potential damage to collateral structures.