Evaluation of The Effect of Diode Laser on Root Canal Disinfection, Canal Cleanliness, Fracture Resistance of Tooth Structure and Bond Strength to Root Canal Dentin An in Vitro Study

Abstract

This study was designed to assess the effect of diode laser as final irrigation procedure on root canal disinfection, root canal cleanliness, fracture resistance of tooth structure, and bond strength of epoxy resin sealer to root canal dentin. A total of 160 extracted single-rooted teeth were used for this study, all canals were prepared using a ProTaper rotary files to a size Protaper (F4) for the full working length. The teeth were divided into two experimental groups according to the presence or absence of diode laser, group A: were finally irrigated using saline, and a high power 980 nm diode laser, group B: were finally irrigated using 5 ml of 17% EDTA followed by 5 ml of 5.25% NaOCl. Each group were subdivided into four subgroups (n=20) according to the data to be evaluated, subgroup A1, and subgroup B1: evaluated for canal disinfection, subgroup A2, and subgroup B2: were evaluated for canal cleanliness, subgroup A3, and subgroup B3: evaluated for fracture resistance of tooth structure, subgroup A4, and subgroup B4: evaluated for bond strength of resin sealer to root canal dentin. The diode laser 980-nm was set at 2.5W continuous wave in scanning mode, the optical fiber tip worked in contact mode, moving coronally in circular movements over the root canal wall at a speed of 2 mm/s. This process was repeated 4 times with total irradiation time for each tooth is approximately 38 s. For evaluation of canal disinfection, the standard strains of E. fecalis ATCC29212 was used, which were sub-cultured in agar plate. and were incubated at 37°C for 24-h period, checked for bacterial growth, and pure, single E. feacalis colony were then isolated. At the end of the incubation period teeth were prepared to collect bacterial sample from each root canal, samples were then immersed in TSA broth in Eppendorf tubes. The colony forming units (CFU) grown was counted, and the Polymerase chain reaction was also performed.