Ablation of carious dental tissue using an ultrashort pulsed laser (USPL) system.

Abstract

The aim of the study was to investigate the efficiency of caries removal employing an ultrashort pulsed laser (USPL) and to compare the results regarding to the ablation rate of sound enamel and dentin including surface texture. The study was performed with 59 freshly extracted carious human teeth. Two cavities with an edge length of 1 × 1mm per tooth were created: one in the dental decay and one in sound hard tissue. For this purpose a 9-W Nd:YVO4 laser with a center wavelength of 1,064nm and a pulse duration of 8ps at a repetition rate of 500kHz was used. A scanner system moved the laser beam across the surface with a scan speed of 2,000mm/s. Ablated volume and roughness R z of the cavity ground were measured using an optical profilometer. Subsequently, the specimens were cut to undecalcified sections for histological investigations. The removal of dental decay (dentin, 14.9mm(3)/min; enamel, 12.8mm(3)/min) was significantly higher (p < 0.05) compared to the removal of sound tissues (dentin, 4.2mm(3)/min; enamel, 3.8mm(3)/min). The arithmetic means of the surface roughness R z were 8.5μm in carious enamel, 15.43μm in carious dentin, 4.83μm in sound enamel and 5.52μm in sound dentin. Light microscopic investigations did not indicate any side effects in the surrounding tissues. Regarding the ablation rate of dental decay using the USPL system, caries removal seems to be much more efficient for cavity preparation.