Acid Resistance of Erbium-doped Yttrium Aluminum Garnet Laser–Treated and Phosphoric Acid–Etched Enamels

Abstract

Objective:To compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser ablation and of phosphoric acid etching on the in vitro acid resistance of bovine enamel. Materials and Methods: Teeth were polished to make the surface flat. The polished enamel was either etched with 37% phosphoric acid for 30 seconds or ablated with a single 33 J/cm 2 pulse from an Er:YAG laser. The control specimens were free from acid etching and laser ablation. Changes in crystal structure, dissolved mineral (calcium [Ca] and phosphorus [P]) contents, and calcium distribution in the enamel subsurface after a pH-cycling process were evaluated. Results: After laser treatment, poor crystal structures improved without forming any new phases, such as tricalcium phosphates. Among the tested enamels, dissolved mineral contents were significantly different (P Ͻ .05). Er:YAG laser-treated enamels had the lowest mineral dissolution (Ca, 13.78 ppm; P, 6.33 ppm), whereas phosphoric acid-etched enamels had the highest (Ca, 15.90 ppm; P, 7.33 ppm). The reduction rate and reduced depth of calcium content along the subsurface were lowest in Er:YAG laser-treated enamels. Conclusion:The Er:YAG laser-treated enamels are more acid resistant to acid attack than phosphoric acid-etched enamels.

Effect of Tooth Surface Preparation on the Bonding of Self-Etching Primer Adhesives

“…This result is similar in part to those of Cardoso and others, 33 who reported no change in microshear bond strength for the ''all-in-one'' adhesive used in their study but in part contrasts with reported significant lowering of bond strength of the two-step adhesive to enamel following Er,Cr:YSGG laser ablation compared with diamond bur-cut enamel. Kim and others 28 reported increased resistance to acid etching of Er:YAGirradiated enamel. Hossain and others 29 reported a significant increase in calcium and phosphate concentrations in irradiated dentin at the cavity floor following Er,Cr:YSSG irradiation.…”

“…11,[22][23][24][25][26][27] Increased resistance to acid etching of Er:YAG-irradiated enamel has been reported. 28 Other authors have reported a significant increase in calcium and phosphate concentrations in irradiated dentin at the cavity floor following erbium, chromium:yttrium, scandium, gallium, garnet (Er,Cr:YSSG) irradiation. 29 Another study reported a significant increase in quantities of calcium in Er,Cr:YSSG-irradiated canine mandibular bone, although the calcium:phosphate ratio was not significantly affected.…”

Shear bond strength of pit and fissure sealants on permanent teeth after several etching protocols: In vitro study

“…8,12,13 However, its use could be justified by the fact that several studies 11,14,15 reported that enamel Er:YAG laser results in a suitable micro retentive pattern for adhesion and can increase enamel acid resistance, 9,15-17 contrary to acid etching which demineralizes enamel surface leading to caries. 15,18 Additionally, it is also thought to have an antibacterial effect by entrapping free ions 12,18,19 and forming remineralization microspaces. 12,19 Nevertheless, laser treatment requires specific considerations as the use of correct tip, 8,15,20 adequate energy, otherwise could result in sub or over ablative energy, causing either flacking 8,18,21,22 or vitrification.…”

“…15,18 Additionally, it is also thought to have an antibacterial effect by entrapping free ions 12,18,19 and forming remineralization microspaces. 12,19 Nevertheless, laser treatment requires specific considerations as the use of correct tip, 8,15,20 adequate energy, otherwise could result in sub or over ablative energy, causing either flacking 8,18,21,22 or vitrification. 8,20 Furthermore, dental tissues response depends on several conditions such as focal distance, irriga- tion, among others; 15,23 in addition, ablation process could lead to produce a microretentive surface on enamel.…”

Comparison on Surface Roughness and Its Effect on Bonding between Conventional Bur and Laser Cut Cavities: An in vitro Study

“…Thus the surface roughness alone may not be a contributing factor, and the quality of the enamel left behind may also play a major factor for bonding of restoration to enamel. 36,37 • During cavity preparation, laser works by causing microexplosions in enamel surface, leading to formation of microcracks. However, these crack propagations are not uniform and their depth is variable.…”