ＣＯ２レーザーの保存修復への応用に関する基礎的研究

Abstract

This study was designed to investigate the effects of CO2 laser irradiation on the dentin microstructure, dentin adhesion of resin composites and dental pulp. An artificial caries lesion was produced on the bovine dentin, immersing in 0.4 mol/l acetic acid. Three kinds of dentin (sound dentin, outer or inner caries dentin) surfaces were pretreated by the laser irradiation, acid etching or no-treatment. The tensile adhesion-test of these pretreated dentin surfaces was performed. The changes in these dentin surfaces by the various treatments including the laser irradiation and the resin-dentin interfaces were examined by the SEM. Furthermore, histopathological study using monkey teeth was conducted to examine the effect of the laser irradiation on the dental pulp. Histopathological changes in the pulp were found at 3 and 90 days after the operation. The findings were as follows: 1. The outer highly and inner partially decalcified layers produced in the bovine dentin were each approximately 200 microns in thickness. 2. The bond strength of the resin composites to the laser pretreated sound dentin was approximately 40 kgf/cm2. Those of the laser pretreated outer and inner decalcified dentins were about 60 kgf/cm2. 3. At the initial stage, the laser irradiation (output power 3W : irradiation period 0.5 second) exhibited a slight pulpal response, producing irritation dentin formation in the latter stage without any severe histopathological change.