DYE-ENHANCED ABLATION OF ENAMEL BY PULSED LASERS

Laser removal of dental hard tissue has been proposed as a replacement for or augmented approach to the dental handpiece. The main limitatio n for widespread usage of lasers in dentistry has been inefficient abl ation of dental hard tissue, accompanied by potential laser-induced da mage to the surrounding tissue. The research focuses on a novel approa ch for enhancement of tissue ablation and confinement of laser interac tion to a small tissue volume by controlled placement of an exogenous dye on the enamel surface. Studies were done with both pulsed alexandr ite and pulsed Nd:YAG lasers, with indocyanine green and India ink, re spectively, used as photo-absorbers. These dye-enhanced laser processe s demonstrated the feasibility of this technique for cavity preparatio n. While control studies produced little or no appreciable crater, ave rage preparation depth for the dye-enhanced ablation was from 1 to 1.5 mm, with a diameter of approximately 0.6 mm. Knoop hardness measureme nts show that, surrounding the crater, there is a small annular region slightly softened by the laser action. SEM studies of the interior st ructure of the tooth did not show significant damage to the surroundin g tissue. Temperature measurement studies indicated that the pulsed na ture of the laser, combined with the photoabsorbing dye, effectively p revented significant temperature rise at the pulp. The remarkable effe ctiveness of this technique in creating cavity preparations and the ab sence of any notable collateral damage to the surrounding tissue sugge st that dye-enhanced pulsed-laser ablation could be used as an alterna tive to the dental handpiece in selected procedures.