Abstract
BACKGROUND: The objective of this study was to investigate the effect of bonded substrate, zirconia surface conditioning and the interaction between them on the shear bond strength of monolithic zirconia. METHODS: Forty-eight monolithic zirconia discs were CAD-CAM fabricated and divided into two groups according to surface treatment either as milled and universal primer application (Monobond N, Ivoclar-Vivadent) (P) or sandblasting then universal primer application (Monobond N) (SP). Each main group was further divided into three test groups according to the bonded substrate: dentin (DSP, DP), composite (CSP, CP) or resin modified glass ionomer (RMGI) (GSP, GP). Adhesive resin cement (Multilinik automix, Ivoclar-Vivadent) was used for bonding. Specimens were stored in water bath for six months before thermal cycling for 10,000 cycles to mimic intra oral condition. All specimens underwent shear bond strength test (SBS) using a universal testing machine. Two and one-way ANOVA and Bonferroni Post Hoc tests were used for statistical analyses. RESULTS: The means ± SD SBS of all test groups were recorded in (MPa). DSP group showed the highest mean SBS (22.65 ± 2.0) followed by DP group (18.61 ± 2.55). Meanwhile, GSP and GP groups showed the lowest mean SBS (4.77 ± 0.09, 4.57 ± 0.73 respectively). CONCLUSION: Sandblasting with priming is recommended as a monolithic zirconia surface treatment method. Dentin is the most reliable substrate followed by composite.