No abstract

No abstract

No abstract

No abstract

No abstract

In extreme situations when it is impossible to use a MG, keeping the teeth in maximum intercuspal position is less harmful. Despite this, the use of any MG is beneficial and assists in dampening the generated stress. The thicker the device, the greater the capacity for decreasing the damage in all structures. The use of individual protectors for each patient is even more beneficial for preventing trauma during at-risk activities of impact.

The objective of this study was to evaluate the durability of bond strength between a resin cement and aluminous ceramic submitted to various surface conditioning methods. Twenty-four blocks (5 x 5 x 4 mm(3)) of a glass-infiltrated zirconia-alumina ceramic (In-Ceram Zirconia Classic) were randomly divided into three surface treatment groups: ST1-Air-abrasion with 110-mum Al2O3 particles + silanization; ST2-Laboratory tribochemical silica coating method (110-microm Al2O3, 110-microm silica) (Rocatec) + silanization; ST3-Chairside tribochemical silica coating method (30-microm SiO(x)) (CoJet) + silanization. Each treated ceramic block was placed in its silicone mold with the treated surface exposed. The resin cement (Panavia F) was prepared and injected into the mold over the treated surface. Specimens were sectioned to achieve nontrimmed bar specimens (14 sp/block) that were randomly divided into two conditions: (a) Dry-microtensile test after sectioning; (b) Thermocycling (TC)-(6,000x, 5-55 degrees C) and water storage (150 days). Thus, six experimental groups were obtained (n = 50): Gr1-ST1 + dry; Gr2-ST1 + TC(;) Gr3-ST2 + dry; Gr4-ST2 + TC; Gr5-ST3 + dry; Gr6-ST3 + TC. After microtensile testing, the failure types were noted. ST2 (25.1 +/- 11) and ST3 (24.1 +/- 7.4) presented statistically higher bond strength (MPa) than that of ST1 (17.5 +/- 8) regardless of aging conditions (p < 0.0001). While Gr2 revealed the lowest results (13.3 +/- 6.4), the other groups (21.7 +/- 7.4-25. 9 +/- 9.1) showed statistically no significant differences (two-way ANOVA and Tukey's test, alpha = 0.05). The majority of the failures were mixed (82%) followed by adhesive failures (18%). Gr2 presented significantly higher incidence of ADHESIVE failures (54%) than those of other groups (p = 0.0001). Both laboratory and chairside silica coating plus silanization showed durable bond strength. After aging, air-abrasion with 110-microm Al(2)O(3) + silanization showed the largest decrease indicating that aging is fundamental for bond strength testing for acid-resistant zirconia ceramics in order to estimate their long-term performance in the mouth.

The aims of this study were to investigate 1) the influence of cleansing methods after saliva contamination and 2) aging conditions (thermocycling and water storage) on zirconia shear bond strength (SBS) with a resin cement. One hundred and eighty zirconia specimens were sandblasted with 50 μm aluminum oxide particles, immersed in saliva for one minute (with the exception of the control group, [C]), and divided into groups according to the cleansing method, as follows: water rinse (W); 37% phosphoric acid gel (PA); cleaning paste (ie, Ivoclean®) containing mainly zirconium oxide (IC); and 70% isopropanol (AL). Scanning electron microscopy was done to qualitatively evaluate the zirconia surface after each cleansing method. For the SBS test, resin cement buttons were bonded to the specimens using a dedicated jig. SBS was evaluated according to standard protocols after 24 hours, 5000 thermal cycles (TC), or 150 days of water storage. Statistical analysis was performed using two-way analysis of variance and Tukey test (p<0.05). Data showed a significant effect for the 150 days of water storage, TC, and 24 hours of water storage (150 days < TC < 24 hours). Group comparisons showed that PA < AL and W < IC and C. SBS ranged from 10.4 to 21.9 MPa (24 hours), from 6.4 to 14.8 MPa (TC), and from 2.9 to 7.0 MPa (150 days). Failure analysis revealed a greater percentage of mixed failures for the majority of the specimens and a smaller percentage of adhesive failures at the ceramic-resin cement interface. Our findings suggest that Ivoclean® was able to maintain adequate SBS values after TC and 150 days of storage, comparable to the uncontaminated zirconia.