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OBJECTIVES: The aim of this study was to evaluate the clinical performance of silorane-based composite restorations applied after different surface treatments. MATERIALS AND METHODS: This controlled and randomized clinical trial included 26 patients with class I restoration indications. The teeth were randomly assigned to the following treatments: control 1/G1, silorane specific self-etching adhesive (P90 self-etch primer and bond) + silorane-based composite resin (Filtek™ P90 low shrink posterior restorative); G2, 37% phosphoric acid + silorane specific self-etching adhesive + silorane-based composite resin; G3, blasting with aluminum oxide + silorane specific self-etching adhesive + silorane-based composite resin; and control 2/G4, self-etching adhesive (Adper™ SE Plus self-etch adhesive) + dimethacrylate-based composite resin (Filtek™ P60 posterior restorative). The clinical performance was evaluated at baseline and after 1 year. RESULTS: A total of 141 restorations were made and evaluated. For all clinical criteria evaluated, no significant difference was found between the surface treatments at baseline and after 1 year (p > 0.05). After 1 year, only the group with 37% phosphoric acid + silorane specific self-etching adhesive (G2) showed a significant reduction in marginal adaptation (p < 0.05). CONCLUSION: In general, all surface treatments showed an adequate clinical performance for silorane-based composite resin in class I restorations. However, a reduction in the marginal adaptation after 1 year was found when additional phosphoric acid etching was used prior to silorane specific self-etching adhesive. CLINICAL RELEVANCE: The use of phosphoric acid etching prior to specific self-etching adhesive can adversely affect the marginal adaptation of silorane-based restorations.

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STATEMENT OF PROBLEM: Hydrofluoric acid etching modifies the cementation surface of ceramic restorations, which is the same surface where failure is initiated. Information regarding the influence of hydrofluoric acid etching on the cyclic loads to failure of ceramic crowns is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the influence of different hydrofluoric acid concentrations on the fatigue failure loads of feldspathic ceramic crowns. MATERIAL AND METHODS: Eighty feldspathic ceramic crowns were cemented with resin cement to identical simplified complete crown preparations machined in a dentin-like polymer. The preparations were etched with 10% hydrofluoric acid for 60 seconds and received a primer coating. Before cementation, the intaglio of the ceramic crowns was treated with 1 of 4 surface conditionings (n=20): nonconditioned (control, CTRL), or etched for 60 seconds with different hydrofluoric acid concentrations: 1% (HF1), 5% (HF5), and 10% (HF10). A silane coupling agent was applied on this surface of all crowns, which were cemented to the preparations. Each crown was cyclically loaded in water with a G10 epoxy-glass piston positioned in the center of the occlusal surface. Fatigue failure loads of ceramic crowns were obtained by the staircase approach after 500000 cycles at 20 Hz. Mean failure loads were analyzed by 1-way ANOVA and the Tukey test (α=.05). RESULTS: Mean failure loads of groups CTRL (245.0 ±15.1 N), HF1 (242.5 ±24.7 N), and HF10 (255.7 ±53.8 N) were statistically similar (P>.05), while that of the HF5 group (216.7 ±22.5 N) was significantly lower (P<.05). CONCLUSIONS: HF5 acid had a negative effect on the fatigue loads of the tested feldspathic ceramic crowns, while HF1 and HF10 acids did not change the fatigue resistance.

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Esta pesquisa avaliou a resistência de união ao cisalhamento de braquetes metálicos (Rocky Mountain Orthodontics) fixados à cerâmica, variando condicionamento ácido, aplicação do silano e ciclagem térmica. Quanto ao silano, comparou-se o Clearfil Ceramic Primer, que contém um monômero ácido em sua formulação, com o Rely X Ceramic Primer, desprovido do monômero. Foram confeccionados 120 discos em cerâmica IPS Empress Esthetic (Ivoclar) com 8 mm de diâmetro por 5 mm de espessura e separados em oito grupos (n=15): Grupos 1, 2, 5 e 6: ácido fluorídrico a 10% por um minuto; Grupos 1 a 4: silano com monômero ácido; Grupos 5 a 8: silano sem monômero ácido; Grupos 1, 3, 5 e 7: 1.000 ciclos de 5°C e 55°C, 30 segundos cada banho. Em seguida, os braquetes foram fixados à cerâmica com o compósito Transbond XT e fotoativados com luz emitida por diodo (LED – UltraLume 5), com 1100 mW/cm2. As amostras foram estocadas em água destilada a 37°C por 24 horas e submetidas ao teste de resistência ao cisalhamento em uma máquina de ensaio Instron à velocidade de 0,5 mm/min. Os dados foram submetidos à análise de variância e ao teste de Tukey (p < 0,05). Obtiveram significância estatística o aumento da adesividade com o condicionamento ácido e a redução de resistência com a ciclagem térmica. Na comparação entre os silanos, não houve diferença estatisticamente significante. Todos os experimentos atingiram valores de resistência superiores aos estabelecidos para uso clínico.

This study evaluated the shear bond strength of metallic brackets (Rocky Mountain Orthodontics) bonded to ceramic, varying acid etching, silane application, and thermocycling. Concerning silane, Clearfil Ceramic Primer, which contains an acid monomer in its formulation, was compared to Rely X Ceramic Primer, devoid of this monomer. 120 IPS Empress Esthetic (Ivoclar) ceramic disks were made with a diameter of 8 mm and thickness of 5 mm. The specimens were divided into eight groups (n=15): Groups 1, 2, 5, 6: hydrofluoric acid 10% for one minute; Groups 1 to 4: silane with acid monomer; Groups 5 to 8: silane without acid monomer; Groups 1, 3, 5, 7: thermocycled 1,000 times at 5°C and 55°C for 30 seconds. After that, the brackets were bonded to the ceramic with Transbond XT composite and cured with light-emitting diode (LED – Ultralume 5) at 1100 mW/cm². All samples were stored in distilled water at 37°C for 24 hours and submitted to shear bond strength test in an Instron testing machine at a crosshead speed of 0.5 mm/min. The data were submitted both to Anova and Tukey’s Test (p < 0,05). Statistical significance was found both in the adhesiveness increase with the acid etching as well as in the resistance decrease with thermocycling. By comparing the silanes, no statistical significance was found. All the experiments reached shear bond strength values higher than those established for clinical use.

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The aim of this study was to evaluate the effect of desensitizing agents on the micro-shear bond strength of adhesive systems to dentin. Forty bovine teeth were divided into 8 groups (n=5): G1--Single Bond (SB); G2--GH.F + SB; G3-- Desensibilize + SB; G4--essensiv + SB; G5 --ingle Bond 2 (SB2); G6--H.E + SB2; G7--esensibilize + SB2; G8--Dessensiv + SB2. In all of the groups, the desensitizing agents were applied after phosphoric acid etching and before the dentin adhesive application. Z250 composite resin tubes were bonded on the treated surface. After 24 hours, the teeth were tested in a universal machine. Data were submitted to ANOVA and Tukey's test (5%). The results showed that the groups where Desensibilize and Dessensiv were applied exhibited smaller bond strength values.

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The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 x 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, specimens were stored in artificial saliva for 0, 24, 72 h, or 7 d and then immersed in 37% phosphoric solution. At 15, 30, 60, 90, and 120 s, 5-ml aliquots were extracted. A control group of specimens was not bleached. Ca(2+) concentrations were measured by atomic absorption spectrophotometry. A larger amount of Ca(2+) was extracted from enamel by phosphoric acid after the application of 30% carbamide peroxide. Twenty-four hours after bleaching, significantly more Ca(2+) was extracted from bleached than from control specimens at all time-points, and this greater susceptibility to the action of the acid persisted for at least 1 wk after bleaching.

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PURPOSE: To assess in vitro the effect of Er:YAG laser irradiation distance on dentin surface morphology, by SEM. METHODS: 60 sound human third molars were employed to obtain discs (approximately equal to 1mm thick), that were polished to standardize the smear layer. Discs were randomly assigned to six groups (n=10) and sequentially bisected. Five groups (including both disc halves of each sample) received Er:YAG laser irradiation (80mJ/2Hz) for 20s, according to the irradiation distance (11, 12, 14, 16 or 17mm) and one was the control group. In the lased-groups, one disc half was separated for superficial analysis without subsequent acid-etching and the other half received phosphoric acid for 15 seconds. In the control group, one disc half was treated with phosphoric acid and no superficial treatment was done in the other half. Specimens were prepared for SEM. RESULTS: Er:YAG laser-irradiated specimens, regardless of the irradiation distance, showed an irregular and scaly surface, with intense ablation of the intertubular dentin, mainly when the irradiation was performed in the focused mode (12 mm). The smear layer was removed and dentin tubules were opened, however, no tubule enlargement was found, unlike the group that only received acid application. The irradiation with 17 mm resulted in a surface appearance more homogeneous than those presented with other distances closer to the focus. The subsequent acid-etching on the lased surfaces decreased the superficial irregularities with partial exposure and enlargement of dentin tubules, in all the tested irradiation distances.

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O objetivo deste trabalho foi avaliar in vitro a microinfiltração marginal de três sistemas adesivos, sendo Grupo I)sistema convencional de um passo com condicionamento ácido prévio, Grupo II)sistema autocondicionante de dois passos e Grupo III)sistema adesivo autocondicionante de um passo. Foram selecionados 15 pré-molares e confeccionados preparos cavitários ocluso-proximais tipo "slot" nas faces mesiais e distrais e divididos em 3 grupos. Terminadas as restaurações, os espécimes foram submetidos à termociclagem e imersos em azul de metileno a 0,5 por cento. Após sofrerem um corte transversal, as maostras foram fotografadas e avaliado o grau de infiltração marginal. Todos os grupos apresentaram infiltração atingindo pelo menos a junção amelodentinária enquanto o Grupo III mostrou também infiltração dentinária. O teste de Kruskal-Wallis demonstrou que não houve diferença estatística entre os grupos I e II, mas foi significativo em relação ao III. Conclui-se que nenhum dos três sistemas estudados foi capaz de evitar totalmente a microinfiltração.

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