Innovative surface treatments for improved ceramic bonding: Lithium disilicate glass ceramic

Objective To investigate the effect of novel surface treatments on adhesion (shear bond) strength of a self-adhesive resin cement to lithium disilicate glass ceramic (LD). Materials and methods A total of 336 LD (IPS e.maxCAD, Ivoclar-Vivadent) specimens (7mm × 7mm × 2.0mm) were embedded in acrylic resin, wet-ground on 180 and 400 SiC papers for 20s, ultrasonicated in distilled water for 10min and air-dried. Samples were randomly divided into 4 study groups according to surface treatment: 5% hydrofluoric acid/20s (HF); non-thermal plasma/20s (NTP); 5% hydrofluoric acid/20s plus non-thermal plasma/20s; no treatment (NT). Each group was divided into 7 sub-groups (n = 12) for silanization with 4 experimental silane primers, 2 commercially available primers or no silanization (control). The specimens were assembled for shear bond strength testing (Ultradent Bonding Assembly), bonded with resin cement (Speed CEM, Ivoclar-Vivadent) and light cured (Bluephase Style@1.100mW/cm2, Ivoclar-Vivadent) for 20s. Specimens were tested after 24h and 90 days storage in water at 37°C. Data were analyzed by 3-Way Anova and Tukey test (α = 5%). Results In general, bond strength values for acryloyl- and styryl-functional silane primers were significantly higher than the other types of silanes. Storage significantly affected the adhesion (bond) strength for most of the groups (p < 0.001). Higher adhesion (bond) strengths to LD appear to be a result of a proper combination of surface treatment and silanization. Significance Increased adhesion strength to lithium disilicate glass ceramic can be obtained with some experimental silane primers combined with HF surface pretreatment.