Effect of Erbium-yttrium, scandium, gallium and garnet (ErYSGG) laser on the bond strength of lithium disilicate ceramics

Objectives: To assess the bond strength of LD ceramics with resin composite material and surface conditioning using Er:YSGG laser and HF acid. Methods: Thirty LD ceramic (Emax, Ivoclar vivadent) discs were prepared using hot pressing technique and treated with hydroflouric acid (Group-1-HF acid) (9%) (n=10) and Er-yttrium, scandium, gallium and garnet laser (Group-2-ER-YSGG laser) (Waterlase iPlus, 10 Hz and power of 0.5 W, pulse duration of 230 mu s) (n=10). Ten specimens were left untreated to be included as controls (Group-3-Control). All the specimens were treated with Adper Single Bond adhesive (3MESPE, St. Paul, MN, USA). Multicore buildups (3mmx3mm) were performed using a rubber mold on the ceramic surfaces and cured using LED light-curing unit for 140 sec. All specimens were tested using shear bond test and failure modes were assessed with a stereomicroscope and scanning electron microscope. Data was analysed using ANOVA and Tukey Kramer multiple comparisons test. Results: The maximum and minimum shear bond strength values were achieved in HF Acid specimens (Group-1) (28.15 +/- 4.72 MPa) and control specimens (13.47 +/- 3.14 MPa) respectively. Specimens treated with HF acid showed significantly higher bond strength in comparison to laser treated and control specimens (p<0.01). Laser treated specimens had significantly higher bond strength as compared to controls (p<0.01). Conclusions: Hydrofluoric (HF) acid treatment showed significantly better outcomes than YSGG laser surface treatment.