ER:Yag lazerin laminate veneer ile diş yüzeyi arasındaki bağlantı dayanımına etkisi The effect of ER:Yag laser on bond strength between the laminate veneer and the tooth surface

Abstract

The purpose of the current study is to evaluate the effect of Er:YAG laser on the shear bond strengths of porcelain laminate veneer materials with different thickness and compositions. 96 non-carious extracted bovine permanent incisors were used. The teeth were randomly divided into eight groups (n=12). Ceramic discs having thicknesses of 0,5 mm and 1 mm and a diameter of 5 mm were fabricated from feldspathic ceramic and leucite-reinforced ceramic blocks. 96 ceramic discs were prepared for 8 groups consisting of 4 control ((feldspathic ceramic-0.5 mm (FK-0,5), feldspathic ceramic -1mm (FK-1), leucite-reinforced ceramic-0.5 mm (LK-0,5), leucite-reinforced ceramic (LK-1)) and 4 experimental groups ((feldspathic ceramic-0.5 mm (FL-0,5), feldspathic ceramic -1mm (FL-1), leucite-reinforced ceramic-0.5 mm (LL-0,5), leucite-reinforced ceramic (LL-1)). Ceramic disks were bonded to the tooth surfaces following the instructions of the manufacturer. Er:YAG laser was applied to the experimental groups with a power of 4.2 Watt (140 mJ x 30 Hz) for 6 s with scanning method. Shear strength test was performed 1 s after the laser application with a crosshead speed of 1 mm/min at universal testing machine. Failure mode was qualified as adhesive, cohesive or adhesive+cohesive by the aid of a stereomicroscope. The debonded tooth and ceramic surfaces of one sample from each group was analysed with scanning electron microscope (SEM). The data were subjected to statistical analysis by One-way Anova and Tukey HSD post hoc tests. p-value < 0,05 was considered significant. The results revealed statistically significant differences (p≤0.05) between the mean shear bond strength of the control groups and the laser groups. When the different porcelain veneer materials having the same thickness were compared, the difference between groups was not statistically significant (p>0.05). Similarly, there was no statistically significant difference between the groups with different thicknesses of same porcelain veneer materials (p>0.05). The Er:YAG laser application significantly reduces the shear bond strength between the porcelain laminate veneer and the tooth required for debonding. However, ceramic thickness and composition did not have any significant effect on the shear bond strength between the porcelain laminate veneer and the tooth after laser application.