(PO135) The Effect of Radial Firing Tip Insertion Depth and Irrigation on Carbonization of Dentin in Extracted Human Canines Using an Er,Cr:YSGG Laser

Abstract: The objective of this study was to compare the effect of radial firing tip (Biolase) insertion depth and irrigation on the presence of dentin carbonization in extracted human canines when using an Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser (Biolase Waterlase Express). Twenty canines were accessed and instrumented. Group 1 received three runs of intracanal debridement (RAPID Endo Protocol) from a depth 1 mm short of working length with distilled water irrigation turned on. Three runs of radial disinfection (RAPID Endo Protocol) were then performed from the same depth with irrigation turned off. Instead, a 30-gauge side-vented needle was used to fill the canal with distilled water between each run. Group 2 received three runs of intracanal debridement with the laser only inserted halfway down the root. In place of radial disinfection, three additional runs of intracanal debridement with irrigation were performed. Teeth were decoronated and sectioned vertically. Three blinded interpreters evaluated canal walls for the presence of carbonization using an operating microscope. All samples had carbonization present. Group 2 had a significantly lower carbonization score (T-test, p = .001). Analysis of a distribution graph shows that group 1 had carbonization in the apical and coronal half of the roots. Only three samples from group 2 had carbonization in apical sites, likely due to misinterpreting middle versus apical sites. An Er,Cr:YSGG laser can cause carbonization of dentin when used with a radial firing tip, regardless of insertion depth or whether irrigation is used.