Effect on New Silica-coating on Resin Bonding to Y-TZP Ceramic

Objective: The aim of this investigation was to evaluate the effect of silica coating using Perhydropolysilazane (PHPS) on the resin bonding to yttria-stabilized zirconia (Y-TZP) ceramic. Methods: Y-TZP ceramic plates (Cercon smart ceramics) were processed with the CAM system. Two 5% PHPS solutions as the precursor for silica (silicon dioxide), NP-110 and NL-120, were applied on ground ceramic plates with 2000-grit SiC paper by the flow technique. PHPS coated plates were heat-treated by a dental furnace according to an effective temperature-time program determined by FTIR. Silica coated plates were silanized using Ceramic primerII(GC) and steal rods were cemented with Linkmax (GC). After 1day storage, bond strengths were assessed by direct tensile bond test (chs: 1mm/min) and mean bond strengths were statistically analyzed using ANOVA and t-test. Also, an effectiveness of two conditioning methods to the silica surface, H₂O₂ immersion and UV irradiation were evaluated. Results: the means tensile strength and sd values (MPa) were; Without pre-treat: 8.25±1.15, NP-110(300°C,3h): 9.63±3.21, NL-120(500°C, 3h): 15.30±3.06, NL-120 (500°C, 10m): 13.69±4.03, NL-120(500°C, 10m/H2O2): 13.87±5.36, NL-120 (500°C,10m/UV): 17.48±2.19. There was no significant improvement in bond strength for silica coating with NP-110 containing amine-catalyst. Fractures occurred at the interface between silica layer and ceramic. However, relatively high initial bond strength was achieved by NL-120 containing Pd-catalyst. Especially, the significantly highest bond strength (p<0.05) of resin cement to ceramic was obtained for silica-coated with 5% NL-120 (500°C, 10m) followed by UV irradiation(185nm, 10m). All fracture occurred within the cements. Conclusion: silica coating with NL-120 followed by UV irradiation is an effective surface condition method for bonding resin luting agents to Y-TZP ceramic.