5. Durability of Luting Cement to Zirconia Ceramics Applied with Different Surface Modifications

「Introduction」The aim of the present study was to evaluate the bonding durability of resin-based luting cement to partially stabilized tetragonal zirconia (Y-TZP) achieved by combination treatment of tribochemical (TBC) treatment and two different phosphate acid ester monomers.「Materials and Methods」Three surface treatments were used: (1) sintering flat specimens were used as a non-modification (NMD) surface; (2) using an alumina sandblasting (ASB) treatment, alumina powder was blasted onto the bonding surface of zirconia specimens; and (3) TBC treatment, which used silica-coated alumina particles (Rocatec(TM) Soft, 3 M ESPE), were blasted onto the bonding surface of zirconia specimens. This was followed by application of a silane coupling agent (ESPE-sil, 3 M ESPE) applied for 5 min. We used one resin-based luting cement (Rely-X ARC) and two phosphate acid ester monomers (EP: Epricord, Kuraray; AZ: AZ primer, Shofu) for each surface modification. The bonding specimen was placed in deionized water at 37℃ and stored for 24 h. The other groups were subjected to 30,000 cycles of a thermal stress durability test, with immersion in deionized water at 5℃ and 60℃ for one min. Shear bond tests were performed using a universal testing machine at 1 mm/min. We observed SEM photographs of the fracture surface.「Results and Discussion」Combination treatment using EP and AZ after TBC treatment could achieve a durable bond, since these shear bond strengths of after thermal stress showed no significant difference (p>0.05) compared with those of stored for 24 h. These results suggested that the phosphoric acid ester monomer can cooperate with a silane coupling agent and selectively adsorb the Y-TZP surface.