Effect of surface pretreatments on the microtensile bond strength of lithium-disilicate ceramic repaired with composite resin.

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 hot-pressed 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 mm2 of cross-sectional area for µTBS testing. Statistical analysis was performed with one-way ANOVA and Student-Newman-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.

Effect of Surface Pretreatments on the Microtensile Bond Strength of Lithium-Disilicate Ceramic Repaired with Composite Resin

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 mm2 of cross-sectional area for µTBS testing. Statistical analysis was performed with one-way ANOVA and Student-Newman-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.

O objetivo deste estudo foi avaliar a influência dos tratamentos de superfícies e a temperatura de secagem do silano na resistência de união de resina composta à cerâmica de disilicato de lítio. Vinte blocos (7x7x5 mm) de cerâmica à base de disilicato de lítio foram fabricados e aleatoriamente divididos em quatro grupos: G1: condicionamento com ácido fluorídrico a 9,5% por 20 s e secagem do silano com ar à temperatura ambiente; G2: condicionamento com ácido fluorídrico a 9,5% por 20 s e secagem do silano com ar aquecido a 45± 5 °C; G3: jateamento com partículas de óxido de alumínio de 50 µm e secagem do silano com ar aquecido a 45 ± 5 °C; G4: jateamento com partículas de óxido de alumínio de 50 µm e secagem do silano com ar à temperatura ambiente. Após os tratamentos, o adesivo Adper Single Bond 2 foi aplicado, fotoativado e foi construído um platô de resina composta (Filtek Z250). Cada espécime foi armazenado em água destilada a 37 °C por 24 h e cortados em forma de palito de área adesiva de 1 mm2 para a realização do teste de microtração. Os dados foram submetidos à ANOVA e ao teste de Student-Newman-Keuls (α=0,05). As médias (D.P.) dos valores de resistência de união em MPa foram: G1: 32,14 (7,98), G2: 35,00 (7,77) e G3: 18,36 (6,17). G1 e G2 apresentaram maiores valores de resistência de união que G3 (p<0,05). Não houve diferença estatística entre as médias dos valores dos grupos G1 e G2 (p>0,05). Levando-se em consideração a resistência de união, o pré-tratamento de cerâmica de disilicato de lítio com ácido fluorídrico e aplicação de silano pode ser uma alternativa para o reparo de restaurações de cerâmicas com resinas compostas, enquanto que o pré-tratamento de superfície com o jateamento deve ser evitado.

Dentin hypersensitivity after treatment with desensitizing agents: a randomized, double-blind, split-mouth clinical trial.

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 (?=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.

Dentin hypersensitivity after treatment with desensitizing agents: a randomized, double-blind, split-mouth clinical trial

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 (?=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.

O objetivo desse estudo foi avaliar a eficiência de dois agentes dessensibilizantes na redução da hipersensibilidade dentinária, em um estudo clínico aleatório do tipo boca-dividida e duplo-cego. Setenta e sete dentes de 13 pacientes que apresentavam algum grau de sensibilidade à sondagem e/ou estímulo ao ar foram tratados com um dos seguintes agentes dessensibilizantes: Oxa-Gel (G1), Sensi Kill (G2) e gel placebo (G3-controle). De acordo com o teste t pareado, todos os tratamentos, inclusive o placebo, foram capazes de reduzir os escores para ambos os estímulos. A análise dos dados pelos testes de ANOVA e de Tukey (?=0,05) demonstrou que os escores de sensibilidade foram significantemente menores somente para o Sensi-Kill em comparação aos outros produtos (Oxa-Gel e placebo) quando o estímulo ar foi aplicado. Pode-se concluir que o tratamento com Sensi-Kill apresentou um desempenho ligeiramente melhor na redução da hipersensibilidade dentinária quando comparados aos outros agentes dessensibilizantes.