ABSTRACT
Abstract To evaluate the effect of acidic challenge on erosion depth and topographic characteristics of different materials used as occlusal sealants. Two hundred specimens of five sealant materials (Fuji IX, Ketac Molar, Fuji II, Equia and Clinpro) and forty bovine teeth enamel samples (control) were prepared and exposed to acidic challenge. The specimens were immersed in four different solutions (orange juice, coke drink, citric acid or distilled water) under mildly shaken conditions for 3 days. The erosion depth profiles were measured using a profilometer and Scanning Electron Microscope (SEM). Two-way ANOVA with Tukey post-hoc test was performed to evaluate the interactions. Sealant material and acidic challenge had significant effects on erosion depth. Among the materials, Fuji II presented the highest mean of erosion depth after immersion in orange juice, coke drink, and citric acid. All materials groups presented higher erosion depth values after immersion in the citric acid solution, except Clinpro. Bovine enamel presented higher erosion depth values compared to all materials when submitted to erosive challenge. Sealant materials submitted to the acidic challenge presented different degrees of erosion and topographic modification; however, they are less susceptible to erosion than bovine teeth enamel.
ABSTRACT
Objective: To evaluate the influence of immediate dentin sealing (IDS) and mechanical methods for removing the temporary cement on the bond strength between dentin and resin cements. Material and Methods: Bovine incisors were ground until dentin exposure and divided according to two factors: "dentin surface treatment"' - cleaning with manual dental excavator (DE), with Robinson bristle brush and pumice paste (PP) or IDS application with Single Bond 2 (IDS/SB+PP) or Single Bond Universal (IDS/SBU+PP) plus cleaning with PP; and "resin cement" - Self-adhesive (RelyX U200) or conventional cement with self-etching adhesive (Multilink Automix). Simulating provisional restoration, acrylic resin plates were cemented onto the dentin surface (with or without IDS) with a non-eugenol temporary cement, and stored in distilled water (37 ºC; 7 days). The acrylic plates were removed, the dentin surface was cleaned (PP or DE), and starch tubes were positioned on the dentin where the resin cements were applied. After 24 h, the specimens were submitted to a microshear test (wire-loop method). Results: Two-way analysis of variance showed statistically significant influence of dentine surface treatments (p< 0.001) and resin cement (p= 0.001) in the bond strength values. The IDS/SBU+PP/U200 (7.24 MPa) and IDS/SBU+PP/MULTI (6.40 MPa) groups presented higher values when compared to cleaning with DE (DE/U200= 4.60 MPa; DE/MULTI= 1.45 MPa) and PP (PP/U200= 3.74 MPa; PP/MULTI= 3.14 MPa). Statistical difference was also found between the cements when dental excavator treatment was used (RelyX U200 Ë Multilink Automix). The IDS/SBU+PP protocol presented a higher percentage of cohesive failures. The micrographs showed differences in dentin surface characteristics among the groups. Conclusion: Immediate dentin sealing increased the bond strength of the resin cements to dentin compared to mechanical cleaning only, regardless the resin cement. (AU)
Objetivo: Avaliar a influência do selamento dentinário imediato (IDS) e dos métodos mecânicos de remoção do cimento provisório na resistência de união entre dentina e cimentos resinosos. Materiais e Métodos: Incisivos bovinos foram desgastados até a exposição da dentina e divididos de acordo com dois fatores: "tratamento da superfície dentinária" - limpeza com cureta dentária manual (DE), com escova de cerdas Robinson e pasta de pedra-pomes (PP) ou aplicação de IDS com Single Bond 2 (IDS/SB +PP) ou Single Bond Universal (IDS/SBU+PP) mais limpeza com PP; e "cimento resinoso" - autoadesivo (RelyX U200) ou cimento convencional com adesivo autocondicionante (Multilink Automix). Simulando a restauração provisória, placas de resina acrílica foram cimentadas na superfície dentinária (com ou sem IDS) com um cimento provisório sem eugenol e armazenadas em água destilada (37 ºC; 7 dias). As placas de acrílico foram removidas, a superfície dentinária foi limpa (PP ou DE) e tubos de amido foram posicionados na dentina onde os cimentos resinosos foram aplicados. Após 24 h, os corpos-de-prova foram submetidos ao ensaio de microcisalhamento (método wire-loop). Resultados: A análise de variância de dois fatores mostrou influência estatisticamente significativa dos tratamentos de superfície dentinária (p< 0,001) e cimento resinoso (p= 0,001) nos valores de resistência de união. Os grupos IDS/SBU+PP/U200 (7,24 MPa) e IDS/SBU+PP/MULTI (6,40 MPa) apresentaram valores maiores quando comparados à limpeza com DE (DE/U200= 4,60 MPa; DE/MULTI= 1,45 MPa) e PP (PP/U200= 3,74 MPa; PP/MULTI= 3,14 MPa). Uma diferença estatística também foi encontrada entre os cimentos quando o tratamento com cureta dentária foi usado (RelyX U200 Ë Multilink Automix). O protocolo IDS/SBU+PP apresentou maior percentual de falhas coesivas. As micrografias mostraram diferenças nas características da superfície dentinária entre os grupos. Conclusão: O selamento dentinário imediato aumentou a resistência de união dos cimentos resinosos à dentina em comparação com a limpeza mecânica apenas, independentemente do cimento resinoso.(AU)