Carbon dioxide (CO₂) laser effects on dental hard tissues

Research has indicated that the CO₂ laser has numerous potential applications for treatment procedures involving dental hard tissues. Altering enamel, dentin, and dental porcelains for endodontic, prosthodontic, preventive, and operative purposes appears to be readily possible with laser technology which currently exists. However, utilizing CO₂ laser energy at levels sufficient to alter these hard tissues and materials raises the possibility of damaging temperature elevations in surrounding tissues. The research described here investigates temperature changes across lased dentin using exposure parameters of sufficient magnitude to alter the caries susceptibility of dental enamel. Dentin is utilized in this study because it is the primary protective barrier between the pulp and insults from the external environment, and it is the foundation tissue upon which the enamel is attached. Dentin specimens of various thicknesses were prepared from non-carious teeth. A 350, 700 and 1000 μm specimen was selected from each of three teeth. Each section received four CO₂ laser exposures. A thermistor was placed on the dentin surface opposite each laser exposure site and the temperature rise was recorded for each exposure. The mean temperature elevations ranged from a low of 0.17°C (1000 μm, 0.1 sec. exposure, 1.2 W) to a high of 1.05°C (350 μm, 0.1 sec. exposure, 2.4 W). A 1mm focal spot was used for all exposures. It would appear that single laser exposures of the magnitude described here will result in only small temperature changes across relatively thin sections of dentin. Further research is necessary relating to temperature elevations when utilizing multiple exposures.