Shear bond strength of luting cements to fixed superstructure metal surfaces under various seating forces

PURPOSE: In this study, the shear bond strengths (SBS) of luting cements to fixed superstructure metal surfaces under various seating forces were investigated. MATERIALS AND METHODS: Seven different cements [Polycarboxylate (PCC), Glass-Ionomer (GIC), Zinc phospahate (ZPC), Self-adhesive resin (RXU), Resin (C&B), and Temporary cements ((RXT) and (TCS))] were bonded to a total number of 224 square blocks (5×5×3 mm) made of one pure metal [Titanium (CP Ti) and two metal alloys [Gold-Platinum (Au-Pt) and Cobalt-Chrome (Co-Cr)] under 10 N and 50 N seating forces. SBS values were determined and data were analyzed with 3-way ANOVA. Pairwise comparisons and interactions among groups were analyzed with Tukey's simultaneous confidence intervals. RESULTS: Overall mean scores indicated that Co-Cr showed the highest SBS values (1.96±0.4) (P .05). The PCC cement showed the highest mean SBS score (3.59±0.07) among all cements tested (P < .00), while the resin-based temporary luting cement RXT showed the lowest (0.39±0.07) (P < .00). CONCLUSION: Polycarboxylate cement provides reliable bonding performance to metal surfaces. Resin-based temporary luting cements can be used when retrievability is needed. GIC is not suitable for permanent cementation of fixed dental prostheses consisting of CP Ti or Au-Pt substructures.

Adhesion of 10-MDP containing resin cements to dentin with and without the etch-and-rinse technique

PURPOSE: This study evaluated the adhesion of 10-MDP containing self-etch and self-adhesive resin cements to dentin with and without the use of etch-and-rinse technique. MATERIALS AND METHODS: Human third molars (N=180) were randomly divided into 6 groups (n=30 per group). Conventional (Panavia F2.0, Kuraray-PAN) and self-adhesive resin cements (Clearfil SA, Kuraray-CSA) were bonded to dentin surfaces either after application of 3-step etch-and-rinse (35% H3PO4 + ED Primer) or two-step self-etch adhesive resin (Clearfil SE Bond). Specimens were subjected to shear bond strength test using the universal testing machine (0.5 mm/min). The failure types were analyzed using a stereomicroscope and quality of hybrid layer was observed under a scanning electron microscope. The data (MPa) were analyzed using two-way ANOVA and Tukey's tests (alpha=.05). RESULTS: Overall, PAN adhesive cement showed significantly higher mean bond strength (12.5 +/- 2.3 - 14.1 +/- 2.4 MPa) than CSA cement (9.3 +/- 1.4 - 13.9 +/- 1.9 MPa) (P<.001). Adhesive failures were more frequent in CSA cement groups when used in conjunction with two-step self-adhesive (68%) or no adhesive at all (66%). Hybrid layer quality was inferior in CSA compared to PAN cement in all conditions. CONCLUSION: In clinical situations where bonding to dentin substrate is crucial, both conventional and self-adhesive resin cements based on 10-MDP can benefit from etch-and-rinse technique to achieve better quality of adhesion in the early clinical period.