CHARACTERISTICS OF ND-YAG SCULPTURED CONTACT PROBES AFTER PROLONGED LASER APPLICATION

This study analyzed the functional and structural characteristics of c one, hemisphere, and modified sculptured contact fibers (1,000 mum) af ter 1 hour of continuous Nd:YAG laser application. Continuous laser ap plication was performed on live porcine tissue using 20 watts of power . The fiber's appearance under a microscope as well as the power outpu t was recorded after 0, 5, 10, 20, 30, 45, and 60 minutes of continuou s laser application. (N = 3 for each fiber). At time 0, all fibers tra nsmitted from 49 to 56% of the initial 20 watts (W); power transmissio n decreased to less than 9% relative power transmission after 20 minut es and then plateaued. The fibers exhibited severe distortion and carb onization of the surface where laser had been applied with evidence of quartz melting and shattering after only 10 minutes. By 30 minutes of laser application, all three fibers were fractured and essentially in distinguishable from one another; moreover, the fibers exhibited simil ar power transmission, and cutting and coagulation activity, as determ ined by a panel of independent, double-blinded surgeons. These data le ad us to conclude that 1) Nd:YAG contact laser effects result from the rmal heating of the fiber tip with subsequent tissue injury, 2) the un ique structural configuration of the fiber's sculptured tip are lost a fter several minutes of laser application without appreciable change i n functional integrity, and 3) fibers may be manually fractured allowi ng for multiple uses without significant sacrifice of power transmissi on or surgical utility. (C) Wiley-Liss, Inc.