Histologic effects of a high-repetition pulsed Nd:YAG laser on intraoral soft tissue

摘要

Abstract: High-repetition rate, fiberoptic-delivered Nd:YAG lasers have increased oral soft tissue laser applications. This study focused on three parameters: the temperature rise occurring in deeper tissue during excision, the histology of thermal coagulation during excision of oral tissue, and effects of accidental exposure to adjacent hard tissue. Thermocouples were placed 5.0 $POM 0.5 mm in bone below fresh bovine gingiva and at the same depth in tongue; temperatures in the underlying tissue were measured during laser excision. An Nd:YAG laser with 100 $mu@s pulse duration was used to excise the tissue using a 200 or 300 $mu@m diameter fiber in contact with the tissue. The soft tissue was excised using constant force and rate with laser powers of 1.5, 3, 5, and 10 W, and a variety of pulse rates. The tissue was bioprepared, sectioned and stained with hematoxylin and eosin. The width and depth of the tissue removed as well as lateral and deep thermal coagulation were measured in histologic sections with a measuring microscope (10x). Multifactor randomized ANOVA showed that probe diameter and repetition rates were not significant variables (p $LSEQ 0.05) but that temperature increased with laser power. Excision began between 2 and 4 W regardless of repetition rate. Excision efficiencies were determined for power and repetition rate. Within the parameters tested in this study, the pulsed fiberoptic-delivered Nd:YAG laser did not cause detrimental temperature rise or deep thermal coagulation in the excision of oral soft tissue. !12