Lasers in endodontics. Part 2: Root canal wall cleanliness and modification

It is well established that thorough cleaning and shaping of the root canal (RC) system is essential for successful RC treatment. Current chemomechanical cleaning methods do not always achieve this goal. Due to the high energy content and specific characteristics of laser light, laser treatment has been proposed for both cleaning and disinfecting the RC system. This paper reviews the literature covering the effect of CO2, diode, Nd:YAG, KTP, Er:YAG and Er,Cr:YSGG lasers on the RC wall, together with the interaction between laser light and target, and the inherent limitations of laser use inside the RC system. On the basis of recent literature, it can be concluded that certain lasers can help in removing the smear layer and debris, they can modify the morphology of the RC wall and that there are inconsistent findings with regard to interactions between lasers and the RC wall, perhaps due in part to variations in irradiation parameters (a lack of standards for irradiation parameters is the cause). The use of laser energy to induce cavitation and acoustic streaming of irrigants is now being explored as an alternative for ultrasonic activation. Unfortunately, there is still much to be proven regarding the clinical usefulness of lasers, as there are no correctly designed clinical studies that include non-laser control groups and evaluate endodontic treatment outcome following the use of lasers. Keywords: cavitation, EDTA, endodontics, laser, root canal, smear layer