Abstract
Objective: To evaluate the shear bond strength of a recent adhesive system used in the cementation of zirconia. Material and Methods: Overall, 72 zirconia specimens (Zirconzhan) were divided and randomized into 3 groups according to the type of surface treatment: G1 no treatment + adhesive system; G2 blasted with aluminum oxide + adhesive system and G3 tribochemical treatment (Rocatec Plus) + adhesive system. Half of each group (n = 12) had bond strength evaluated on two occasions: 24 hours after cementation, kept stored in distilled water at 37 ° C without thermal cycling, and after thermal cycling (5000 cycles, 5°C-55°C). Data were analyzed by ANOVA with Tukey's post-test (α≤0.05). Results: At first moment, G1 and G3 showed higher bond strength (8.64 ± 3.43 MPa and 6.55 ± 2.27 MPa) compared to G2, with no statistically significant difference between them. After thermal cycling, G3 showed higher bond strength (7.70 ± 1.82 MPa). Conclusion: Initially, only the adhesive system promoted higher bond strength, but after thermal cycling,bond strength decreased. The best treatment to promote high bond strength to zirconia is to associate tribochemical treatment with the adhesive system; most failures observed after thermal cycling were mixed and cohesive, showing a mechanical imbrication of the adhesive system, suggesting that there is no chemical bond; and the surface of the group with greater bond strength after thermal cycling showed more surface irregularities compared to the other groups.
Highlights
There are many materials in dentistry to restore teeth function and aesthetics in the oral cavity
Material and Methods: Overall, 72 zirconia specimens (Zirconzhan) were divided and randomized into 3 groups according to the type of surface treatment: G1 no treatment + adhesive system; G2 blasted with aluminum oxide + adhesive system and G3 tribochemical treatment (Rocatec Plus) + adhesive system
The best treatment to promote high bond strength to zirconia is to associate tribochemical treatment with the adhesive system; most failures observed after thermal cycling were mixed and cohesive, showing a mechanical imbrication of the adhesive system, suggesting that there is no chemical bond; and the surface of the group with greater bond strength after thermal cycling showed more surface irregularities compared to the other groups
Summary
There are many materials in dentistry to restore teeth function and aesthetics in the oral cavity. One of the advantages of zirconia crowns compared to metal-ceramic crowns is esthetic, as the latter can, over long periods, show a dark halo in dental contouring, while zirconia is metal-free. Another advantage of zirconia compared to alumina and lithium disilicate crowns is its high hardness and greater strength to fracture [4]. Zirconia used is that in the tetragonal crystalline phase, partially stabilized by yttria (Y-TZP), because pure zirconia is unstable for dental use [2]. Due to its zirconia polycrystalline tetragonal structure stabilized by yttria, it becomes resistant to some acids used for cementation [6,7]
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