RESUMEN
Context: Heat treatment allows the use of direct composite resins for fabrication of inlays/onlays restorations because it improves some mechanical and physical properties. Aim: The aim of this study is to analyze the influence of heat treatment on the water sorption and solubility of direct composite resins compared with an indirect composite resin. Materials and Methods: A total of 50 cylindrical specimens were fabricated (6 mm diameter × 2 mm high) and divided into five groups (n = 10): G1 (FillMagic without heat treatment-control 1), G2 (heat‑treated FillMagic), G3 (P60 without heat treatment-control 1), G4 (heat‑treated P60) and G5 (indirect resin Epricord-control 2). After fabrication, the specimens were placed in a desiccator containing silica gel and maintained at 37°C for 24 h. This cycle was repeated until a constant weight was achieved (m1). Following, the specimens were stored in individual flasks containing 2 ml of distilled water in an oven at 37°C. The specimens were weighed after intervals of 1, 7 and 21 days of immersion in water (m2). After 21 days of storage in water, the specimens were once again desiccated until a constant weight was achieved (m3). The mean diameter and thickness of specimens were obtained using a digital pachymeter. Statistical Analysis Used: Two‑way analysis of variance and Tukey’s test were used to compare the sorption and solubility (α = 0.05). Results: The type of resin significantly influenced the sorption (P = 0.01) and solubility (P = 0.00). The heat treatment also significantly influenced the sorption (P = 0.026) and solubility (P = 0.01). Conclusion: It was concluded that the heat treatment is an additional curing method that improves strength to the sorption and solubility of composite resins.
RESUMEN
PURPOSE: To evaluate the shear bond strength of a self-etch adhesive and an etch-and-rinse adhesive when bonded to bovine enamel and dentin. METHODS: The labial surfaces of 28 bovine mandibular incisors were wet ground to achieve a flat enamel or dentin surface. A 1-step self-etch adhesive and a 3-step etch-and-rinse adhesive were bonded to enamel or dentin according to the manufacturer's instructions (Adper Easy One and Adper Scotchbond, respectively). A composite resin cylinder (Filtek Z350 XT) was built upon the adhesive layer using a silicon mold (2 mm in diameter × 3 mm high). The specimens were stored in 37°C distilled water for 24 h. The bond strength was measured by a universal testing machine at a crosshead speed of 1.0 mm/min. Student's t-test was used to compare bond strength values between adhesives at the 95% confidence level. RESULTS: For the enamel specimens, Adper Scotchbond had significantly higher values of bond strength than Adper Easy One (P=0.007). For the dentin specimens, there were no statistically significant differences between adhesives (P=0.12). CONCLUSION: Adper Easy One showed lower shear bond strength than Adper Scotchbond on enamel. For dentin, Adper Easy One showed bond strength similar to Adper Scotchbond.
OBJETIVO: Avaliar a resistência ao cisalhamento de adesivo autocondicionante e adesivo convencional ao esmalte e dentina bovinos. METODOLOGIA: As superfícies vestibulares de 28 incisivos mandibulares bovinos foram lixadas, sob refrigeração, para obtenção de superfícies de esmalte ou dentina planas. Um adesivo autocondicionante de passo único e um convencional de três passos foram utilizados de acordo com as instruções dos fabricantes (Adper Easy One and Adper Scotchbond, respectivamente). Um cilindro de resina composta foi confeccionado sobre a camada adesiva usando um molde de silicone (2 mm de diâmetro × 3 mm altura). Os espécimes foram armazenados a 37°C em água destilada por 24 h. A resistência de união foi mensurada através de máquina de ensaios universal à velocidade de 0.1 mm/min. Teste t de Student comparou os resultados de resistência de união entre os adesivos com nível de confiança de 95%. RESULTADOS: Para os espécimes de esmalte, Adper Scotchbond apresentou valores significativamente maiores que Adper Easy One (P=0.007). Para espécimes de dentina, não houve diferenças significativas entre os adesivos (P=0.12). CONCLUSÃO: Adper Easy One mostrou menor resistência ao cisalhamento do que Adper Scotchbond no esmalte. Para dentina, Adper Easy One mostrou resistência de união similar ao Adper Scotchbond.