Morphological study of the effects of CO2 laser emitted at 9.3 mu m on human dentin

Objective: The purpose of this study was to investigate the effects of dent in ablation using a carbon dioxide (CO2) laser emitted at 9.3 mu m by scann ing electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) , Background Data: There have been no reports on effects of CO2 laser irrad iation emitted at 9.3 Ecm on dentin by SEM and CLSM, Methods: Thirty extrac ted human teeth showing no clinical signs of caries were used. All teeth we re horizontally sectioned to approximately 200 mu m thickness and sections were irradiated using a 9.3 pm CO2 laser at different parameters as follows : 26 mi [energy density (ED) 53.0 J/cm(2)] and 30 mJ (ED 61.1 J/cm(2)), Aft er laser irradiation, samples were treated with sodium hypochlorite, staine d using rhodamine-123, and observed with CLSM followed by SEM procedures. R esults: No craters or cracks were observed, but many small molten and rehar dened particles were documented on the sample surface using SEM. Some small cracks were seen in the subsurface layer, and some patent dentinal tubules were detected using CLSM. Conclusion : These results suggest that laser ir radiation at these parameters affected the sample surface only (less than 2 0 mu m) and would be less harmful to thermal damage of dental pulp for dent in ablation.