The aim of this study was to evaluate the influence of ceramic surface treatments and silane drying temperature on the microtensile bond strength (μTBS) of a resin composite to a lithium disilicate ceramic. Twenty blocks (7x7x5 mm) of lithium disilicate-based hotpressed ceramic were fabricated and randomly divided into 4 groups: G1: acid etching with 9.5% hydrofluoric acid for 20 s and drying silane with room-temperature air; G2: acid etching with 9.5% hydrofluoric acid for 20 s and drying silane with 45 ± 5 °C warm air; G3: airborne-particle abrasion with 50 μm aluminum oxide particles and drying silane with 45 ± 5 °C warm air; G4: airborne-particle abrasion with 50 μm aluminum oxide particles and drying silane with air at room-temperature. After treatments, an adhesive system (Single Bond 2) was applied, light-cured and direct restorations were built up with a resin composite (Filtek Z250). Each specimen was stored in distilled water at 37 °C for 24 h and cut into ceramic-composite beams with 1 mm 2 of cross-sectional area for μTBS testing. Statistical analysis was performed with one-way ANOVA and StudentNewman-Keuls test (α=0.05). μTBS means (S.D.) in MPa were: G1: 32.14 (7.98), G2: 35.00 (7.77) and G3: 18.36 (6.17). All specimens of G4 failed during the cutting. G1 and G2 presented significantly higher μTBS than G3 (p<0.05). There was no statistically significant difference between G1 and G2 (p>0.05). As far as the bond strength is concerned, surface pretreatment of lithium-disilicate ceramic with hydrofluoric acid and silane application can be used as an alternative to repair ceramic restorations with composite resin, while surface pretreatment with sandblasting should be avoided.

The aim of this study was to evaluate the efficacy of two desensitizing agents in the reduction of dentin hypersensitivity in a randomized, double-blind, split-mouth clinical trial. Seventy-seven teeth from 13 patients that presented some degree of sensitivity to probing and/ or air stimulation were treated with one of the following desensitizing agents: Oxa-Gel (G1), Sensi Kill (G2) and placebo gel (G3 -control). According to paired t-test, all treatments, even the placebo gel, were capable of reducing sensitivity scores for both stimuli.Analysis of data by ANOVA and Tukey's test (α=0.05) showed that the sensitivity scores were significantly lower only for Sensi Kill in comparison to the other products (Oxa-Gel and placebo), when air stimulus was applied. It may be concluded that treatment with Sensi Kill presented a slightly better performance in reducing dentin hypersensitivity when compared to the other desensitizing agent.

Context:Non-carious cervical lesions are usually associated with dentin hypersensitivity. The use of oxalic acid in restorations of these lesions could be beneficial in relieving pain.Aims:To evaluate the use of oxalic acid in restorations of non-carious cervical lesions.Settings and Design:A randomized clinical trial.Subjects and Methods:One operator placed 90 restorations in 20 volunteers of both sexes, with at least two lesions to be restored with the techniques: Control — Restoration with total-etch technique and Experimental — Restoration with pretreatment with oxalic acid followed by application of adhesive system. The restorative adhesive system used was XP Bond/Durafill. The restorations were directly assessed by two independent examiners using a modified United States Public Health Service (USPHS) method at baseline, 6 and 12 months, taking into account the following criteria: Retention (R), marginal integrity (MI), marginal discoloration (MD), postoperative sensitivity (S), caries (C), and anatomic form (AF).Statistical analysis used:The data were statistically analyzed using the Fisher exact and McNemar tests. The level of significance was set at 5%.Results:After 1 year, the results of restorations clinically satisfactory obtained for the control and experimental group respectively were: R (97% / 89%), MI (100% / 100%), MD (100% / 100%), S (100% / 100%), C (100% / 100%), and AF (100% / 100%).Conclusions:The use of oxalic acid as an agent of dentin pretreatment did not influence the clinical performance of restorations in non-carious cervical lesions after 1 year.