Bond Strength of Lithium Disilicate Ceramic with Different Surface Treatments

Objective: The objective of this study was to evaluate the effect of post etch cleaning, silane and heated silane on microtensile bond strength of lithium-disilicate hot pressed glass ceramic when bonded to composite resin. Methods: 24 blocks of lithium-disilicate were fabricated (Hot Pressing) and bonding surfaces were etched using 9.5% hydrofluoric acid. Seven experimental groups (including control) resulted from the various surface treatment combinations which included, post-etch cleaning (PEC) (37.5% Phosphoric acid for 1 min , rinse with water for 20 seconds and ultrasonic bath immersion),  silane application (S) and heat (100°C for 5 minutes) or air dried silane. Silica based hot pressed ceramic blocks were also fabricated and surface treated to be used as a control group. Ceramic and composite resin blocks were bonded using an adhesive resin and light cured composite resin as a luting agent, under standard conditions. A total of 210 specimen sticks (8 x 1mm²) were subjected to micro-tensile testing. The means of µ-tbs were analyzed with one-way ANOVA and Tukey-Kramer multiple comparisons test. The tested specimens were analyzed for mode of failure using scanning electron microscopy. Results: The highest µ-tbs value (42.6 ±3.70 Mpa) was achieved for lithium disilicate ceramics with post-etch cleaning and heat dried silane. The maximum difference in means was due to post etch cleaning (15.729 Mpa) followed by the effect of ceramic material (7.481 Mpa) and silane (5.883 Mpa). Conclusions: In the surface treatment of lithium-disilicate glass ceramic, post-etch cleaning was the most important step with regards to µ-tbs, followed by silane. Lithium-disilicate ceramics produced significantly higher µ-tbs bond strength values than silica based leucite ceramics (control group).