Resin Bonding to Zirconia Ceramic Using a New Ceramic Primer

"Objectives:" This in vitro study evaluated the tensile bond strength (TBS) of composite resin to zirconia ceramic using a new universal primer. "Methods:" Ninety-six zirconia ceramic disks (e.max ZirCAD, Ivoclar-Vivadent, FL) were divided into 6 groups (n=16) according to surface treatments, cleaning methods and ceramic primers. Disks were either air-abraded with 110 µm alumina particles (ABR) or silica-coated (SC) (Rocatec, 3M ESPE, Germany) followed by removing loose surface particles either with compressed air (A) or with ultrasonic cleaning (U) in alcohol. Then either a conventional silane (S) (Espe Sil, 3M ESPE; FRG) or a universal ceramic primer containing a silane and a phosphate monomer (P) (Monobond Plus, Ivoclar) was applied to the conditioned surface. A total of 6 groups were tested: SC-A-S; SC-U-S; SC-A-P; SC-U-P; ABR-A-P and ABR-U-P. Plexiglas tubes filled with composite resin (Multicore flow, Ivoclar) were bonded to the disks using a composite resin (Multilink Automix, Ivoclar). Bonded specimens (N=8) of each group were stored in 37°C water for 3 days or 150 days with 37,500 thermal cycles (5-55°C) before testing (TBS). Statistical analyses was conducted with three and one-way ANOVAs followed by comparison of means with Tukey's HSD test. "Results:" Artificial aging significantly (P≤0.01) decreased TBS (MPa) for following groups: SC-A-S (38.3±9.7/11.3±5.1.0), SC-U-S (31.5±8.5/4.8±6.9) and ABR-A-P (42.5±7/21.7±6). However, artificial aging did not influence TBS significantly (P>0.05) for groups SC-A-P (44.0±6.4/36.0±7.3), SC-U-P (45.2±4.7/38.1±6.2) and ABR-U-P (44.1±8.9 /33.0±9.0). "Conclusion:" A new universal ceramic primer improved bonding to zirconia ceramic compared to conventional silane. Cleaning methods after air-abrasion had little effect on bonding to zirconia ceramic. Supported by Ivoclar Vivadent, Schaan, Liechtenstein.