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 × 1 mm 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 1,064 nm and a pulse duration of 8 ps at a repetition rate of 500 kHz was used. A scanner system moved the laser beam across the surface with a scan speed of 2,000 mm/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, 14.9 mm(3)/min; enamel, 12.8 mm(3)/min) was significantly higher (p < 0.05) compared to the removal of sound tissues (dentin, 4.2 mm(3)/min; enamel, 3.8 mm(3)/min). The arithmetic means of the surface roughness R z were 8.5 μm in carious enamel, 15.43 μm in carious dentin, 4.83 μm in sound enamel and 5.52 μm 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.

Effect of Different Surface Treatments on Porcelain‐Resin Bond Strength

“…Ultrashort-pulse laser systems are not suitable for direct clinical use; however, many studies have reported on the bond strength of dental tissues subjected to treatments using a UPLS. 26,[37][38][39] Lorenzo et al 26 reported stronger bonding of brackets to enamel treated with a UPLS rather than other laser systems. The ablation from UPLS's is induced by a plasma, which imparts less thermal damage than do the longer pulses of ER:YAG lasers.…”

“…Ultrashort‐pulse laser systems are not suitable for direct clinical use; however, many studies have reported on the bond strength of dental tissues subjected to treatments using a UPLS , . Lorenzo et al reported stronger bonding of brackets to enamel treated with a UPLS rather than other laser systems.…”

Regulation and Measurement of the Heat Generated by Automatic Tooth Preparation in a Confined Space

“…19 High-power pulses with durations that are shorter than the HEAT MEASUREMENT OF AUTOMATIC TOOTH PREPARATION tissue thermal relaxation time are indicated to avoid thermal denaturation of the organic components of the tissues adjacent to the irradiated surfaces, thus the thermal damage induced by the femtosecond laser might be lower than the damage induced by other methods. 21,22 Interactions of USPLs with dental hard tissues are based in the nonthermal aspects of the ablation process. When the laser irradiates the target tissue, it causes ionization and an electron avalanche in the superficial substrate within fractions of a second, which covers the ablation hydrodynamics, resulting in removal of the hard tissue.…”

Imaging of Dental Hard Tissue Surfaces Prepared by an Ultrashort Pulsed Laser System (USPL)

“…The laser utilized for enamel and dentin preparation in the current investigation was an ultrashort pulsed laser system (USPL) (Bello-Silva et al, 2012;Schelle et al, 2013). In a recent study, Engelbach et al (2015) showed the suitability of such a USPL for selective ablation of carious dental hard tissue.…”

“…Laser-irradiated enamel and dentin surfaces show very great similarities to acid-conditioned tooth surfaces (Engelbach et al, 2015). Different investigations have so far yielded no clear results regarding whether laser-conditioned surfaces demonstrate similarly good adhesion of restorations when using conventional acid etching (De Munck et al, 2002;Dunn et al, 2005;Moldes et al, 2009).…”