Showing papers by "Andrea Nóbrega Cavalcanti published in 2011"

Durability of Resin Cement Bond to Aluminium Oxide and Zirconia Ceramics after Air Abrasion and Laser Treatment

Abstract: Purpose: The erbium laser has been introduced for cutting enamel and dentin and may have an application in the surface modification of high-strength aluminum oxide and zirconia ceramics. The aim of this study was to evaluate the durability of the bond of conventional dual-cured resin cements to Procera Al2O3 and zirconium oxide ceramics after surface treatment with air abrasion and erbium laser. Materials and Methods: One hundred twenty Al2O3 and 120 zirconia specimens measuring 3 × 3 × 0.7 mm3 were divided equally into three groups, and their surfaces treated as follows: either untreated (controls), air abraded with Al2O3 particles, or erbium-laser-treated at a power setting of 200 mJ. The surface of each specimen was then primed and bonded with one of two dual-cured resin cements (either SCP-100 Ceramic Primer and NAC-100 or Monobond S and Variolink II) using a 1-mm thick Tygon tube mold with a 0.75-mm internal bore diameter. After 24 hours and 6 months of water storage at 37°C, a microshear bond strength test was performed at a crosshead speed of 1 mm/min. Surface morphology was examined using a confocal microscope, and failure modes were observed using an optical microscope. The data were analyzed using the Kaplan-Meier nonparametric survival analysis. Results: In the case of zirconia, air abrasion and Erbium:yttrium-aluminum-garnet (Er:YAG) laser treatment of the ceramic surface resulted in a significant reduction in the bond strengths of both resin cements after 6 months water storage; however, when the zirconia surface was left untreated, the SCP-100/NAC-100 group did not significantly reduce in bond strength. In the case of alumina, no treatment, air abrasion and Er:YAG laser treatment of the surface led to no significant reduction in the bond strengths of the three SCP-100/NAC-100 groups after 6 months water storage, whereas all three Monobond S/Variolink II groups showed a significant reduction. Conclusion: Er:YAG laser treatment of the zirconia surface did not result in a durable resin cement/ceramic bond; however, a durable bond between a conventional dual-cured resin cement and Procera All Ceram and Procera All Zirkon was formed using a ceramic primer containing the phosphate monomer, MDP, without any additional surface treatment.

Cigarette smoke combined with staining beverages decreases luminosity and increases pigmentation in composite resin restorations.

Abstract: This study evaluated the effect of cigarette smoke combined or not with colored beverages on the color change of a composite resin before and after repolishing procedures. Composite specimens were allocated into six groups (N = 10): 1) control (no colorant); 2) cigarette smoke; 3) coffee; 4) coffee and cigarette smoke; 5) red wine; and 6) red wine and cigarette smoke. During 21 days, groups 2, 4, and 6 were exposed daily to the smoke from 20 cigarettes, and groups 3, 4, 5, and 6 were immersed in coffee or red wine for 4 minutes each day. Color measurements were performed with a spectrophotometer at baseline, after 21 days, and after repolishing procedures. Statistical analysis indicated the exposure to cigarette smoke and staining beverages resulted in decreased luminosity (P = .0001) and increased red pigmentation in most experimental groups (P 7.5). Repolishing resulted in greater luminosity, as well as decreased yellow pigmentation (P < .05). It could be concluded that combined staining agents such as cigarette smoke and red wine irreversibly change resin color regardless of the use of repolishing procedures.

Changes on the color parameters of air-abraded resin composite exposed to different colored beverages.

Abstract: Aim: To evaluate the effect of prophylaxis using sodium bicarbonate and colored beverages on the color parameters of a resin composite. Methods: Eighty specimens (Z350–3M ESPE) were randomly allocated into eight groups (n = 10), according to the combination of staining solution (artificial saliva, cola, red wine, or coffee) and air-powder abrasion with sodium bicarbonate (either performed or not performed). Specimens were immersed in the staining solution for 48 h (two 24-h cycles). Color evaluation was based on the CIELab system. Two measurements were carried out using a spectrophotometer (Commission Internationale de L’Eclairage L* a* b* system) before and after the immersion period. Final measurement data were analyzed by two-way anova/Tukey’s test, and comparisons were made between initial and final measurements by anova/Dunnett’s test, with a 5% significance level. Results: Most comparisons between initial and final measurements were statistically significant. Red wine and coffee significantly affected the color parameters (L*, b*, and ΔE). However, only coffee significantly increased a* values. When compared with untreated surfaces, air-powder abrasion resulted in alterations of b* and a* parameters, but did not affect L* and ΔE. Conclusions: Both colored beverage solutions and air-powder abrasion can affect the color of composite resin restorations.

Efeito da aplicação de primers para metal na resistência de união de cimentos resinosos à zircônia

Abstract: Effect of application of metal primers on the bond strength of resin cements to zirconia The aim of this study was to evaluate the effect of alloy primers on the bond strength (BS) of conventional resin cement and self-adhesive cement to zirconia using the microshear bond strength test. Sixty ceramic plates, with dimensions of 13 x 5 x 1 mm (length x width x thickness), were prepared . The ceramic plates were air-abraded with aluminum oxide and divided into six experimental groups, according to the treatment used (n = 10). The primers and resin cements were applied according to manufacturers’ recommendations and experimental groups. After treatment of the zirconia, resin cement cylinders were constructed on their surfaces by using matrix (Tygon) with 0.7 x 1 mm (diameter x height). The samples were stored in distilled water for 24 hours at 37°C and tested in a universal testing machine (0.5 mm\min, Instron 4411). The data were analyzed by ANOVA (two factors) and Tukey test (α = 0.05). Only the use of Metal Primer II increased the bond strength of all resin cements to zirconia. The self-adhesive RelyX U-100 cement promoted higher bond strength values than Bistite II DC, for all surface treatments. To obtain the highest bond strength to zirconia, it must be used the Metal Primer II and the self-adhesive RelyX U-100 resin cement.