Effect of cement removal technique on morphology at tooth-ceramic margin

Purpose: To evaluate and compare the effect of ceramic primer, adhesives and ageing on the shear bond strength of resin composite with lithium disilicate. Methods andmaterials: Lithiumdisilicate (IPS e.max® CAD HT/A2; Ivoclar Vivadent, Inc.) blocks were sectioned (thickness – 1.5mm), mounted and polished through 600 grid SiC polishing paper. The exposed surface of each specimen was acid etchedwith 5%hydrofluoric acid for 20 s. Specimenswere randomly distributed in 4 groups (n=10) according to surface treatment and aging – Groups 1 and 2: ceramic primer (Monobond® Plus; Ivoclar Vivadent, Inc.) + adhesive (Adhese® Universal; Ivoclar Vivadent, Inc.); Group 3 and 4: adhesive only (ScotchbondTM Universal; 3M ESPE). As per manufacturer’s instructions, application of ceramic primer is not recommended with Scotchbond Universal. Primer and adhesives were applied following manufactures instructions. Adhesives were light cured using polywave LED curing light (Bluephase G2; High mode; Power Intensity – 1100± 50mW/cm2) for 10 s. Specimens were secured in the Ultradent Jig. The resin composite (Tetric EvoCeram (A2)) was condensed in the insert and was light cured for 10 s. After polymerization, specimens were removed from the jig and stored in the incubator for 24h (37 ◦C/100% humidity). Group 2 and 4 were thermo-cycled for 3000 cycles following ISO/TS 11405:2003 (E) standard. Specimens were tested in the Instron Universal Testing Machine using a 1kN load cell with a crosshead speed of 1.0mm/min. Data was analyzed by One-way Univariate Analysis of Variance (ANOVA) and Tukey’s HSD post hoc test (a=0.05). Results: The shear bond strength values (MPa)/(mean±SD) of each group are listed below. Means with different letters are statistically different (a=0.05). Group 1 35.2± 3.7A, Group 2 34.6± 5.9A, Group 3 24.6± 3.2B, Group 4 18.5± 3.5C. Conclusion: Within the limitation of this study, application of ceramic primer along with Adhese Universal showed significantly higher bond strength compared to Scotchbond Universal. The shear bond strength of Scotchbond Universal decreased significantly after aging.