Effect of Er:YAG Laser Irradiation on Shear Bond Strength of Two Porcelain Laminate Veneers Bonded to Tooth Surface

Abstract

Background and Aim: The conventional procedure for removal of porcelain laminate veneers (PLVs) is time-consuming and inconvenient. The purpose of this study was to evaluate the efficacy of Er:YAG laser for debonding of PLVs. Materials and Methods: Forty-eight intact extracted human maxillary anterior teeth received discoid PLVs (24 feldspathic and 24 e-max ceramic). The PLVs had 0.7 mm thickness and 4 mm diameter. After cementation of all PLVs with a light-cure cement, samples were stored at 37ºC distilled water for 48 h. Samples of each ceramic were randomly divided into 3 groups of 8 samples. Then, laser was irradiated on the cemented PLVs as follows: (I) feldspathic PLVs without laser irradiation (control group), (II) feldspathic PLVs with laser irradiation (6 s, 10 Hz, 200 mJ, 2 W), (III) feldspathic PLVs with laser irradiation (6 s, 10 Hz, 300 mJ, 3 W), (IV) e-max PLVs without laser irradiation (control group), (V) e-max PLVs with laser radiation (6 s, 10 Hz, 200 mJ, 2 W), (VI) e-max PLVs with laser irradiation (6 s, 10 Hz, 300 mJ, 3 W). The shear bond strength of all samples was measured using a universal testing machine. We used Mann-Whitney and Kruskal-Wallis tests for data analysis (P<0.05). Results: Laser irradiation decreased the shear bond strength of both ceramics. But this decrease was only significant for the e-max group (P<0.05). No significant difference was found between different laser irradiation powers in the two ceramic groups. Conclusion: Er: YAG laser is effective for debonding of e-max PLVs.

The efficiency of ErCr:YSGG laser on the debonding of different thicknesses of ceramic veneers

“…Many studies have also got comparable results of decreasing in shear bond strength after the laser application despite of using different types of lasers, ceramic materials, luting agent and other experimental conditions 13,21,26 .…”

“…Er,Cr:YSSG laser was used in the current study since it causes fewer thermal effect compared to other lasers like Nd:YAG or CO 2 lasers 20 and its large presence in the dental clinics because of their wide application area in hard and soft tissue procedures. It also emitts a wavelength of 2780 nm and can therefore be effectively absorbed by water and residual monomer present in adhesive resins 21 . The laser parameters were the same as in Phillips study 16 (2012) who considered this parameters to be the safest for pulpal health.…”

“…This is in agreement with Oztoprak et al 9 (2010). Also "thermal ablation" and "photo-ablation" of luting cements have been suggested to be the major mechanism for debonding of all-ceramic restorations 21 . Photoablation and thermal ablation happen when a very high-energy laser light reacts with the luting resin, inducing it to deteriorate 25 .…”