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Objectives: To assess the efficacy of experimental cleaners containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) on the saliva decontamination of ceramic and their influence in restoring zirconia's adherence to resin cement. Materials and methods: Four hundred sixty alumina-blasted zirconia specimens were categorized into saliva-contaminated and uncontaminated groups which were treated with ceramic primer (P), experimental cleaner 1 (C1), C1 followed by P (C1P), experimental cleaner 2 (C2), and C2 followed by P (C2P). Stainless-steel rods were then attached to the specimens using PanaviaV5 cement (Kuraray Noritake Dental; Tokyo, Japan). Tensile bond strength (TBS) test was performed after 24 h and 5000 thermocycling processes. X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurement of the specimen were performed. The TBS data were analyzed by Weibull analysis and three-way ANOVA. Contact angle data were analyzed by two-way ANOVA (α = 0.05). Results: C2P groups showed the highest TBS in all conditions among tested groups. Saliva contamination led to a significant reduction of TBS in primer- and cleaner-treated groups, with no significant impact on C2P. Adhesive failure was predominant in contaminated groups except with the C1P and C2P groups. XPS revealed that a nitrogen peak was observed on contaminated groups but not in primed groups. The contact angle was significantly affected by saliva contamination, the cleaners, and/or ceramic primer usage (p < 0.001). Conclusions: The MDP cleaner followed by the MDP primer protocol may overcome the effect of saliva contamination and improve the resin-ceramic bond strength. Clinical relevance: It is recommended to use a combination of MDP-containing cleaner 2 and ceramic primer as a chair-side chemical pretreatment for zirconia substrate with or without saliva contamination. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the effects of the ratio of different concentrations of silane to 1 wt% 10-methacryloyloxydecyl dihydrogenphosphate (MDP) in primer on the performance and durability of bonding to silica-based and zirconia ceramics. Phosphoric acid–treated lithium–disilicate (LD) and alumina-blasted zirconia specimens were assigned to five groups according to surface chemical treatment with different concentrations of γ-methacryloxypropyltrimethoxysilane (γ-MPTS) to 1 wt% MDP containing primer as follows: S0) without γ-MPTS; S1) 1 wt% γ-MPTS; S2) 2 wt% γ-MPTS; S5) 5 wt% γ-MPTS and S10) 10 wt% γ-MPTS. After priming, stainless-steel rods were bonded to the specimens with PanaviaV5 cement. Tensile bond strength (TBS) test was evaluated after 24-h (TC0) or 5000 thermocycling (TC5K). The wettability of primer-treated surfaces was measured using contact angle measurements. Surface elemental composition of zirconia was determined with X-ray photoelectron spectroscopy (XPS). The TBS data were analyzed using Weibull analysis. Contact angle data were analyzed by three-way analysis of variance (α = 0.05). Before thermocycling, S5 (34.3 ± 4.5 MPa) showed the highest TBS compared to S1 (27.8 ± 5.2 MPa) and S2 (29.7 ± 4.8 MPa), and insignificant difference with S10 (30.6 ± 6.2 MPa) in LD. For zirconia there was no significant difference in all silane containing primers with S0 (p > 0.05). Thermocycling decreased TBS for all experimental groups among both ceramics (p < 0.05). Contact angles increased in S5 and S10 for both LD and zirconia ceramics. XPS analysis revealed that phosphorous peak of MDP was detected after priming. Additionally, silica peak of γ-MPTS coexist with MDP in S5 on zirconia surface. The bond strength of lithium-disilicate ceramics was improved with 5% γ-MPTS in MDP primer. Moreover, increasing percentage of γ-MPTS by more than 5% has not improved the bond strength, conversely, it can alter the long-term durability of the bonded ceramic. MDP primers alone are best suited for efficient bonding of resin cement with zirconia ceramic. Image 1 • Experimental primers can influence the bond strength and durability. • The effective silane-MDP ratio was ceramic materials–dependent. • Thermocycling decreased the tensile bond strength of all experimental primers. [ABSTRACT FROM AUTHOR]