Abstract
To assess intra oral repair of Lithium Disilicate ceramics (LDC) and Yttria Stabilized Tetragonal Zirconia Polycrystal (Y-TZP) using low level laser therapy (LLLT) in comparison to conventional conditioning modalities on repair bond strength of composite resin bonded to ceramic structure. Fifty specimens of LDC and fifty samples of Y-TZP were used. Discs were prepared form each group having a diameter 6 mm and thickness of 2 mm and conditioned using different regimes. Group 1 and 6 were surface treated with bur, group 2 and 7 were conditioned with Nd-YAG (NYL), group 3 and 8 surface was treated with Er,Cr:YSGG (ECL), group 4 and 9 with hydrofluoric acid + salinization (HF+S) and group 5 and 10 were conditioned with A1203 air abrasion (AA). A single layer of Heliobond was scrubbed on the conditioned surface and bonded with composite resin. For shear bond strength testing the specimens were placed in a universal testing machine. A stereomicroscope at 40x magnification was used to analyse failure pattern. The mean repair bond strength was calculated using ANOVA and Tukey's post hoc test at a significance level of (p < 0.05). The highest repair bond strength observed in LDC was (19.57 +/- 3.58 MPa) in group 4 whereas, the lowest score vas displayed in Group 3 (11.88 +/- 1.98 MPa). Similarly, in Y-TZP the highest repair SBS values were presented in group 10 (air abrasion) (20.32 +/- 3.21) and the lowest SBS values were exhibited by bur treated group 1 (12.25 +/- 2.33). Failures in group 1, group 2, group 3, group 6, group 7 and group 8 were dominantly adhesive. Whereas, failures in group 4, group 5, group 9 and group 10 were cohesive. HF acid with salinization remains gold standard for conditioning of LDC. AA with salinization is the most effective method to condition YTZP ceramics for better repair bond scores. Alternate methods of conditioning using LLLT (NYL and Er,Cr:YSGG) needs further investigation.