Adhesion of composite to enamel and dentin surfaces irradiated by IR laser pulses of 0.5–35 μs duration

Abstract

The characteristics of laser-treated tooth surfaces depend on the laser wavelength, pulse duration, spatial and temporal laser beam quality, incident fluence, surface roughness, and the presence of water during irradiation. Ablated surfaces are most commonly restored with adhesive dental materials and the characteristics of the ablated surfaces influence adhesion of restorative materials. Previous studies suggest that high bond strengths can be achieved using shorter laser pulses that minimize peripheral thermal damage. In this study, Er:YSGG, Er:YAG, and CO(2) lasers were used at irradiation intensities sufficient to simulate efficient clinical caries removal to uniformly irradiate bovine enamel and human dentin surfaces using a motion control system with a microprocessor-controlled water spray. The degree of spatial overlap of adjacent pulses was varied so as to investigate the influence of irradiation uniformity and surface roughness on the bond strength. Composite resin was bonded to the irradiated surfaces and shear bond tests were used to obtain bond strengths in MPa. The highest results were obtained using the Er:YAG pulses with pulse durations less than 35 mus without the necessity for postirradiation acid etching. Some of these groups were not significantly different from nonirradiated, acid-etch-only positive control groups.

Selective removal of carious human dentin using a nanosecond pulsed laser operating at a wavelength of 5.85 μ m

“…42,43 In this study, the tensile bonding strength between the composite resin and dentin surface was significantly higher under the DFG laser irradiation (12.5 MPa) than under irradiation by the standard dental Er:YAG laser (4.8 MPa). Different failure modes were also observed between the DFG laser and the Er:YAG laser.…”

Long-term effect of Er:YAG laser on adhesion to caries-affected dentin

“…At shorter (50-μs) pulse durations, the output energy is fully absorbed by the target tissue with no or minimal heat created in the underlying tissue [12], less thermal damage [13][14][15], and shorter irradiation time. The reduced heat propagation into dentin can reduce the risk of micro-crack formation and collagen fibril denaturation [16], suggesting that a shorter pulse duration could be a better protocol for irradiating dentin where bonding will be performed [7], as unaltered collagen is key to effective hybrid layer formation and its durability.…”

Effect of dentin laser irradiation at different pulse settings on microtensile bond strength of flowable resin

“…The erbium: yttrium-aluminum-garnet (Er:YAG) laser is one of the most useful types of lasers for dental hard tissues and emits a wavelength (2.94 μm) coincident with the main absorption band of water (3.0 μm). The Er:YAG is also well absorbed in hydroxyapatite 2,5,6) and effectively treats the dentin surface by removing the smear layer in a way that is similar to acid etching, opening dentinal tubules and creating a microscopically rough surface with a micromechanical retention pattern, which is apparently ideal for adhesion 2,[7][8][9] . Moreover, cavity pretreatment with Er:YAG laser has been proposed as an alternative to acid etching of enamel and dentin 9) .…”