IADR Abstract Archives
Various Cleaning Methods for Contaminated Zirconia Effects on Bond Strength
Objectives: The contamination of salivary or serum protein on zirconia restoration may compromise the bond strength. This study is to test the efficacy of five different cleaning techniques with two commonly-used self-adhesive resin cements.
Methods: The cleaning techniques that were tested included: tap water, Zirclean (Bisco), 37% phosphoric acid etchant (Best Etch, Vista Dental products), Pre-coated with primer (Monobond Plus, Ivoclar Vivadent), and experimental cleanser (formulated at GSDM biomaterial lab). For testing the bond strength, custom-made full contour zirconia rings were used. Stainless steel pins were manufactured to fit into these zirconia rings allowing a cement space of 50±5 µm in all the directions. The intaglio of the zirconia rings were particle air-abraded with 50 µm Al2O3 powder and the stainless steel rods were particle air abraded twice with 125 microns Al2O3 powder. A mixture of 0.1mg/mL bovine serum albumin in organic milk was used as a contaminant. After contamination and treatment with the cleaning agents as per instruction, the zirconia rings were cemented onto steel pins using two self-adhesive resin cements, Theracem (Bisco) and Unicem 2 (3M). A custom-made cementation jig was used to ensure the pins perfectly centralized in the zirconia rings. All specimens were stored at 100% humidity for 48-72 hours at 37°C and then subjected to a ‘push-out’ test using an Instron universal machine until failure. The maximum loads were recorded to calculate shear-bond strengths in MPa. The bond strengths of different treatments and cements were compared to the control group using JMP Pro 13 software.
Results: Mean bond strengths of all groups are presented in a bar-graph.
Contamination with protein decreases the cement bond strength significantly. Pre-coating zirconia surface with MDP primer before the contamination significantly improved bond strength values. Bond strengths after cleaning with the experimental cleanser and Zirclean were also significantly improved.
Conclusions: After contamination of zirconia surface, the bond strength using resin cements decreases dramatically. Using proper cleaning agents after contamination to clean or MDP pre-coating to reduce the contamination can positively impact the bond strength of the restoration.
Methods: The cleaning techniques that were tested included: tap water, Zirclean (Bisco), 37% phosphoric acid etchant (Best Etch, Vista Dental products), Pre-coated with primer (Monobond Plus, Ivoclar Vivadent), and experimental cleanser (formulated at GSDM biomaterial lab). For testing the bond strength, custom-made full contour zirconia rings were used. Stainless steel pins were manufactured to fit into these zirconia rings allowing a cement space of 50±5 µm in all the directions. The intaglio of the zirconia rings were particle air-abraded with 50 µm Al2O3 powder and the stainless steel rods were particle air abraded twice with 125 microns Al2O3 powder. A mixture of 0.1mg/mL bovine serum albumin in organic milk was used as a contaminant. After contamination and treatment with the cleaning agents as per instruction, the zirconia rings were cemented onto steel pins using two self-adhesive resin cements, Theracem (Bisco) and Unicem 2 (3M). A custom-made cementation jig was used to ensure the pins perfectly centralized in the zirconia rings. All specimens were stored at 100% humidity for 48-72 hours at 37°C and then subjected to a ‘push-out’ test using an Instron universal machine until failure. The maximum loads were recorded to calculate shear-bond strengths in MPa. The bond strengths of different treatments and cements were compared to the control group using JMP Pro 13 software.
Results: Mean bond strengths of all groups are presented in a bar-graph.
Contamination with protein decreases the cement bond strength significantly. Pre-coating zirconia surface with MDP primer before the contamination significantly improved bond strength values. Bond strengths after cleaning with the experimental cleanser and Zirclean were also significantly improved.
Conclusions: After contamination of zirconia surface, the bond strength using resin cements decreases dramatically. Using proper cleaning agents after contamination to clean or MDP pre-coating to reduce the contamination can positively impact the bond strength of the restoration.
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