Evaluation of bond strength of adhesive systems and resincements to dentin and restorative composites

Orientador: Marcelo GianniniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O atual conceito de união aos tecidos duros dentais é baseado na infiltração de sistemas adesivos em esmalte e dentina, no processo chamado de hibridização. Enquanto a união ao esmalte tem sido considerada um procedimento confiável devido a sua uniforme composição, a união à dentina continua sendo um desafio. O objetivo deste estudo foi avaliar e discutir os conceitos que envolvem os sistemas adesivos odontológicos e as técnicas de cimentação adesiva. O estudo compreendeu quatro avaliações que propuseram analisar: 1- a resistência de união (RU) de alguns sistemas autocondicionantes após uma semana e um ano de armazenamento em água; 2- a RU de cimentos resinosos aos compósitos utilizados na reconstrução dental; 3 e 4- a RU de técnicas de cimentação adesiva. Foram utilizados dentes bovinos nos experimentos 1, 2 e 3; e ensaios de microcisalhamento. Para o experimento 4 foram utilizados dentes humanos e o ensaio de microtração. Os resultados indicaram que: 1- entre todos adesivos testados, o adesivo autocondicionante One-Up Bond F não apresentou redução na RU após um ano; 2- a RU foi maior quando se aplicou adesivo hidrófobo entre o compósito restaurador e o cimento resinoso; 3 e 4- o uso de uma camada intermediária de resina de baixa viscosidade e fotoativação dos cimentos resinosos resultou em maiores valores de RU entre o cimento resinoso e a dentina. Os resultados sugerem que a união à dentina ainda é instável para a maioria dos sistemas adesivos; na união do cimento resinoso ao compósito restaurador, os adesivos hidrófobos são as melhores opções; e as técnicas de cimentação adesiva apresentam melhor desempenho com aplicação de uma camada intermediária de resina de baixa viscosidade e fotoativação do cimento resinosoAbstract: The current concept of bonding to hard dental tissues is based on the infiltration of adhesive systems in enamel and dentin, in the so-called hybridization process. While the enamel bond has been considered a reliable procedure due to its uniform composition, bonding to dentin continues to present challenges. The objective of this study was to assess and discuss the concepts involving dental adhesive systems and the techniques of adhesive cementation. The study included four evaluations to determine: 1- the bond strength (BS) of some self-etching adhesive systems after one week and one year of storage in water; 2- The BS of the resin cements to composites used in dental restoration; 3 and 4- The BS of adhesive cementation techniques. Bovine teeth and micro-shear bond strength tests were used for experiments 1, 2 and 3. For experiment 4, human teeth and micro-tensile tests were used. The results indicated that: 1- among the adhesives tested, the self-etching adhesive One-Up Bond F did not show reduction in BS after one year; 2- the BS was higher when the hydrophobic bond was applied between the filling composite and the resin cement; 3 and 4- the use of an intermediary layer of low viscosity resins, and photoactivation of the resin cements, resulted in higher BS values between the resin cement and the dentin. The results suggest that bonding to dentin is still unstable for the majority of adhesive systems; in the union of the resin cement to the filling composite, hydrophobic adhesives are the best options; and the techniques of adhesive cementation present better performance with the application of an intermediate layer of low viscosity resin and photoactivation of resin cementDoutoradoMateriais DentariosDoutor em Materiais Dentário

Avaliação da resistencia ao cisalhamento da união de sistemas adesivos a dentina

Orientador: Luis Roberto Marcondes MartinsDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaMestrad

Effect of dentin desensitizers on resin cement bond strengths

Introduction: The crown preparation promotes the exposure of dentin tubules. Thus, to avoid post-operative sensitivity, the first approach involves the use of dentin adhesives, and the second one the use of dentin desensitizers. Objective: This study evaluated the effect of dentin desensitizers on microtensile bond strengths (µTBSs) of a resin cement to dentin. Material and methods: Twenty bovine teeth were prepared until obtaining flat dentin surfaces. A standardized smear layer was created (#600-grit SiC paper). The samples were randomly divided into the following four groups (n = 5): no treatment (Control), treatment with Gluma Desensitizer (Heraeus Kulzer), Super Seal (Phoenix Dental) and Teethmate Desensitizer (Kuraray Noritake Dental). The dentin surfaces were then treated with ED Primer II (Kuraray Noritake Dental). Twenty composite blocks, 4 mm thick (Estenia C&B, Kuraray Noritake Dental) were used. The composite surfaces were abraded with aluminum oxide (50 µm), and then silanized. The composite block was bonded to the dentin surface with a resin cement (Panavia F 2.0, Kuraray Noritake Dental) according to he manufacturer’s instructions. After 24-hour storage (37ºC, 100% RH), the bonded samples were cut into beam–shaped microtensile specimens and loaded in tension until failure. Data were analyzed with one-way ANOVA and the Dunnett’s test (α = 0.05). An SEM was used to examine the failure modes. Results: The µTBSs (MPa ± SD) were: 24.4 ± 3.2 (Control), 14.0 ± 5.6 (Gluma Desensitizer), 8.6 ± 4.7 (Super Seal), and 34.7 ± 4.6 (Teethmate Desensitizer), in which there were significant differences among the four groups (p < 0.05). The Teethmate Desensitizer group showed the highest µTBS, while the Super Seal group showed the lowest mean of µTBS to dentin. Conclusion: The efficacy of the desensitizers is material-dependent; Gluma Desensitizer and Super Seal decreased the µTBSs, however, Teethmate Desensitizer improved it

Bond strength of resin cements to leucite-reinforced ceramics: part 2 – after one-year aging in water

The aim of this study was to compare the shear bond strength (SBS) of two resin cements bonded to four leucite-reinforced ceramics after one week and one year of aging. Material and methods: Forty ceramic blocks (4 mm wide, 14 mm length, and 2 mm thick) were used (1 week) and reused at the back side (1 year). The blocks were abraded with aluminum oxide (90 µm) and randomly divided into eight groups for each time. Two dual resin cements (RelyX ARC and RelyX U200 self-adhesive, 3M ESPE) were bonded to ceramics Creapress (CRE – Creation / Klema), Finesse All-Ceramic (FIN – Dentsply / Ceramco), IPS Empress Esthetic (IEE – Ivoclar Vivadent) and Vita PM9 (PM9-Vita). For each resin, time, and ceramic block, after applications of the 10% hydrofluoric acid (for 1 min) and silane, 3 Tygon cut tubes were positioned over each block and filled in with the resin cements (light-cured for 40 s). The tubing molds were removed to expose the bond specimens as cylinders (area=0.38 mm2) stored in relative humidity at 24±2°C for one week and at 37±2°C for one year. All bonds were tested in an Instron in shear (applied of the base cylinder with a thin wire - 0.25 mm) at speed of 0.5 mm/min, until failure. Results: The results were analyzed by ANOVA (resin cements, ceramic systems, and time) and Tukey test (p<0.05) for rank ordering of SBS. The FIN and IEE ceramics did not show significant SBS decreasing on aging with U200. The mean SBS decreasing for all the ceramics was 36% with ARC and 14% with U200 cement. Conclusion: The SBS of ARC cement were significantly lower for all ceramics with aging than that of U200 cement. The SBS of ARC cement was also weakened by aging. FIN ceramic + U200 cement proved to be the most stable and strongest bond strength, and PM9+ARC cement proved to be the weakest bond strength with low stability.The aim of this study was to compare the shear bond strength (SBS) of two resin cements bonded to four leucite-reinforced ceramics after one week and one year of aging. Material and methods: Forty ceramic blocks (4 mm wide, 14 mm length, and 2 mm thick) were used (1 week) and reused at the back side (1 year). The blocks were abraded with aluminum oxide (90 µm) and randomly divided into eight groups for each time. Two dual resin cements (RelyX ARC and RelyX U200 self-adhesive, 3M ESPE) were bonded to ceramics Creapress (CRE – Creation / Klema), Finesse All-Ceramic (FIN – Dentsply / Ceramco), IPS Empress Esthetic (IEE – Ivoclar Vivadent) and Vita PM9 (PM9-Vita). For each resin, time, and ceramic block, after applications of the 10% hydrofluoric acid (for 1 min) and silane, 3 Tygon cut tubes were positioned over each block and filled in with the resin cements (light-cured for 40 s). The tubing molds were removed to expose the bond specimens as cylinders (area=0.38 mm2) stored in relative humidity at 24±2°C for one week and at 37±2°C for one year. All bonds were tested in an Instron in shear (applied of the base cylinder with a thin wire - 0.25 mm) at speed of 0.5 mm/min, until failure. Results: The results were analyzed by ANOVA (resin cements, ceramic systems, and time) and Tukey test (p<0.05) for rank ordering of SBS. The FIN and IEE ceramics did not show significant SBS decreasing on aging with U200. The mean SBS decreasing for all the ceramics was 36% with ARC and 14% with U200 cement. Conclusion: The SBS of ARC cement were significantly lower for all ceramics with aging than that of U200 cement. The SBS of ARC cement was also weakened by aging. FIN ceramic + U200 cement proved to be the most stable and strongest bond strength, and PM9+ARC cement proved to be the weakest bond strength with low stability