Laser Dentistry

I NTRODUCT ION The Er:YAG laser, emitting at 2940 nm, can be a valuable tool for root canal debridement and improved pathogen reduction during endodontic treatment. The ability to successfully negotiate and remove the smear layer and bacteria continues to be a challenge for nonsurgical endodontic treatment in root canal systems. Current instrumentation techniques use both hand and ultrasonic irrigation in an attempt to debride and decontaminate the root canal system, and there are studies with conflicting results regarding the successful and/or complete removal of the smear layer, bacteria, and biofilm from inside the root canal system. Many irrigants such as chlorhexidine, 5.25% sodium hypochlorite, 10% citric acid, and 17% ethylene diaminetetraacetic acid (EDTA) have been used, and studies have shown some variation in their ability to remove all of the microorganisms and smear layer within the intraradicular canal space, but one report indicates that activation (by manual-dynamic, automateddynamic, and sonic means) of those irrigants increases their effectiveness. Researchers continue to seek alternative methods to more effectively debride and penetrate into the dentinal walls of root canal systems. The Er:YAG laser system used in this study has U.S. Food and Drug Administration (FDA) clearance for debriding, cleaning, and enlarging the root canal system. Many studies have evaluated the effects of lasers on root canal walls. Those laser procedures were performed with end-firing tips that were withdrawn with a helical motion in 5 to 10 seconds each cycle, beginning 1 mm from the apex. The canals were tested both dry and wet according to different protocols. Different energy outputs ranging from 75 to 100 mJ at different repetition rates were also used. With previous traditional laser techniques, the irradiated dentin showed both clean and debrided surfaces, with little to no smear layer and opened tubules. However, the surfaces treated when dry showed serious thermal damage.