Methods:
Lithium-disilicate ceramic blocks (5×5×2mm) (IPS Empress2, Ivoclar, Vivadent, Liechtenstein) were fabricated using the hot-pressing technique, specimens surfaces were finished with 1000 grit silicon carbide paper and embedded in acrylic resins (n=50).
The specimens were assigned to 5 groups (n=10), which received the following surface treatments; G1:hydrofluoric acid etching-HF (%9.5) for 60 seconds; G2: 1.5watt; G3: 2.5watt; G4: 6.0watt pulsed laser (Er:Cr:YSGG laser, Biolase, USA) application for 60 seconds respectively. G5: no surface treatment was performed as a control group.
Ceramic primer (3M ESPE) and adhesive (Single Bond,3M ESPE) was applied on the ceramic surfaces, it was followed by resin luting cement (RelyX-ARC, 3M ESPE, MN, USA) to bond the composite cylinders (3×4mm) (Filtek-Z250; 3M ESPE) and light cured for 40 seconds (Optilux-501; Kerr-Demetron, Orange, CA, USA). The bonded specimens were stored in distilled water for 24 hours at 37oC. Shear bond strengths were performed by using an universial testing machine (Instron) at 1mm/min crosshead speed and then calculated to MPa. The data were analyzed by Kruskal-Wallis and Mann-Whitney-U tests.
Results:
The group G1, (HF) (8,42±1,86MPa) achieved a significantly higher shear bond strength than the other groups (p<0.01). G2 (3,88±1,94MPa) and G3 (3,65±1,87MPa), laser groups, showed significantly stronger adhesion than the control group G5 (1,95±1,06MPa) which showed the lowest bonding values (p<0.01) There was no significant differences between G4 laser group (3,59±2,19MPa) and the control group (p>0.05).
Conclusions:
As a surface treatment on all ceramics; laser application did not increase shear bond sterngth as HF acid etching. Higher level of laser energy settings decreased the shear bond strength between the all-ceramic restoration and the resin cement in this study limitations.