RESUMO
PURPOSE: This study evaluated the effects of light exposure times on water sorption, solubility, and polymer cross-linking density of simplified etch-and-rinse adhesives. MATERIALS AND METHODS: Four commercial adhesives (XP Bond, Adper Single Bond 2, Tetric N-Bond, and Ambar) were selected, and resin disks 5 mm in diameter and 1.0 mm thick were prepared and light cured for 20, 40, or 80 s using an LED light-curing unit at 1200 mW/cm2. Water sorption and solubility were evaluated over a 28-day period. For polymer cross-linking density, additional specimens were prepared and their Knoop hardness measured before and after immersion in 100% ethanol. The data from each test were evaluated using a two-way ANOVA and Tukey's test (α = 0.05). RESULTS: The XP Bond adhesive showed higher water sorption (similar to Adper Single Bond 2) and solubility (p < 0.05) than did the other materials. Prolonged exposure times did not reduce the water sorption but did reduce the solubility of all tested materials (p < 0.05). For Ambar, the increase in the exposure time resulted in a significantly lower percent reduction in hardness. CONCLUSION: Water sorption, solubility, and cross-linking density of the materials selected in this study seem to be mainly influenced by the adhesive composition. Prolonged light exposure times reduced the solubility of the materials.
Assuntos
Luz , Cimentos de Resina/química , Água/química , Condicionamento Ácido do Dente/métodos , Adsorção , Resinas Compostas/química , Resinas Compostas/efeitos da radiação , Lâmpadas de Polimerização Dentária , Cimentos Dentários/química , Cimentos Dentários/efeitos da radiação , Adesivos Dentinários/química , Adesivos Dentinários/efeitos da radiação , Etanol/química , Dureza , Humanos , Imersão , Cura Luminosa de Adesivos Dentários/instrumentação , Teste de Materiais , Metacrilatos/química , Metacrilatos/efeitos da radiação , Polimerização , Solubilidade , Solventes/química , Fatores de TempoRESUMO
PURPOSE: To evaluate the effects of the temperature of air used for solvent evaporation on water sorption, solubility, and ultimate tensile strength (UTS) of simplified etch-and-rinse adhesives. MATERIALS AND METHODS: Four commercial simplified etch-and-rinse adhesives (Adper Single Bond 2 [SB]; Te Econom [TE]; XP Bond [XP] and Ambar [AM]) were selected. Disk-shaped specimens were prepared by dispensing the uncured resin into a mold (5.8 mm x 0.8 mm). Solvent evaporation was performed using a warm (60°C) or cold (20°C) air stream for 40 s. After desiccation, the cured specimens were weighed and then stored in distilled water for evaluation of the water diffusion kinetics over a 28-day period. For the UTS measurement, hourglass-shaped specimens of adhesives were prepared and tested in tension. The data from each test were evaluated with two-way ANOVA and Tukey's test at a confidence level of 95%. RESULTS: Water sorption and solubility varied significantly between materials, but no significant difference was observed between warm and cold conditions (p > 0.05). TE and AM showed the lowest water sorption and solubility (p < 0.05). For SB, TE, and XP, the use of a warm air stream resulted in higher ultimate tensile strength (p < 0.05) in both experimental conditions. CONCLUSIONS: The water sorption and solubility of the materials seem to be more influenced by their composition than by the temperature used for solvent evaporation. For some adhesives, the use of a warm air stream can yield higher ultimate tensile strength.