Laser dental hard tissue ablation: Comparison Er-lasers and scanned ultra-short pulse laser

Abstract

Laser treatment of dentine was performed with two free-running Erbium laser systems operated at 3 W average power, and a mode-locked 12-ps Nd:vanadate laser at an average power of 3.5 W. Mean ablated volumes per laser pulse were determined by means of a three-dimensional digital evaluation method. The temporal pulse profiles of the Erbium systems was analysed to explain the ablation rate results. Additionally, the morphology of the laser treated surfaces was examined. Two Erbium laser systems were involved in this study. The Er:YAG laser, emitting at a wavelength of 2940 nm, has a maximum pulse energy of 1.5 J and adjustable pulse repetition rate up to 50 Hz. It was operated in the VSP (variable square pulse) mode. The laser beam is delivered via a mirror articulated arm and outcoupled through a conically shaped sapphire tip. The second system, was an Er,Cr:YSGG laser with a wavelength of 2780 nm, has a maximum pulse energy of 300 mJ and fixed pulse repetition rate of 20 Hz. A fibre delivery system is implemented in this laser. Again, a conically shaped sapphire tip was used. Laser treatment was performed at 3 W and 20 Hz with an air-water spray.