Assessment of radicular dentin permeability after irradiation with CO_2 laser and endodontic irrigation treatments with thermal imaging

摘要

Previous studies have demonstrated that the permeability changes due to the surface modification of dentin can be quantified via thermal imaging during dehydration. The CO_2 laser has been shown to remove the smear layer and disinfect root canals. Moreover, thermal modification via CO_2 laser irradiation can be used to convert dentin into a highly mineralized enamel-like mineral. The purpose of this study is to evaluate the radicular dentin surface modification after CO_2 laser irradiation by measuring the permeability with thermal imaging. Human molar specimens (n=12) were sectioned into 4 axial walls of the pulp chamber and treated with either 10% NaClO for 1 minute, 5% EDTA for 1 minute, CO_2 laser or none. The CO_2 laser was operated at 9.4 μm with a pulse duration of 26 us, pulse repetition rate of 300 Hz and a fluence of 13 J/cm~2. The samples were dehydrated using an air spray for 60 seconds and imaged using a thermal camera. The resulting surface morphological changes were assessed using 3D digital microscopy. The images from digital microscopy confirmed melting of the mineral phase of dentin. The area enclosed by the time-temperature curve during dehydration, ΔQ, measured with thermal imaging increased significantly with treatments with EDTA and the CO_2 laser (P<0.05). These results indicate that the surface modification due to CO_2 laser treatment increases permeability of radicular dentin.