This study evaluated the effect of surface finishing methods on the average surface roughness of resin composites. Seven composites and two polishing systems were used. One hundred and twenty-six conical specimens of each material were prepared in stainless steel molds against a polyester strip. Forty-two of them remained intact and were used as controls. Each half of the remaining samples was polished with either diamond burs or diamond burs + aluminum oxide discs. The results showed no statistical difference in average surface roughness (Ra, µm) between the polyester strip and aluminum oxide discs (p>0.05). However, finishing with diamond burs showed a statistically higher average roughness for all composites (p<0.05). Statistical differences were detected among materials (p<0.05) in the use of diamond burs.

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á=0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01) and Definite (1.89±0.01) shrank significantly less than the other composite resins. SureFil (2.01±0.06), Filtek Z250 (1.99±0.03), and Fill Magic (2.02±0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

ABSTRACT:The vascular changes in the subcutaneous connective tissue of rats induced by dentin bonding systems (one step) was studied and compared to those induced by saline solution (negative control) and Furacin (positive control), during the exudative phase of the inflammatory process. Twenty mg/kg of Evan's blue were injected intravenously in the vein of the rats' penises; 0.1 ml of each substance tested was inoculated in the subcutaneous tissue. After a 3 hour period the animals were sacrificed and their skins were excised and punched out with a standard steel 2.5 cm in diameter. The specimens were immediately immersed in 8 ml of formamide and taken to a double boiler for 72 hours at 37ºC, to remove the dye. The liquid containing the overflowed dye was filtered, analyzed in the spectrophotometer (620 nm) and classified according to the criteria established by Nagem-Filho, Pereira (1976). After statistical analysis, the irritative potential of the substances was ranked as follows: Furacin (severe) > Single Bond and Bond 1 (moderate -no significant differences between the dentin bonding systems tested) > saline solution (not significant as regards the irritation degree). DESCRIPTORS: Dentin-bonding agents; Capillary permeability. RESUMO:Estudaram-se as alterações vasculares do tecido conjuntivo subcutâneo de ratos induzidas por sistemas adesivos dentinários (único passo), comparados com solução fisiológica (controle negativo) e Furacin (controle positivo), durante a fase exsudativa do processo inflamatório. Com esse propósito, injetaram-se intravenosamente, na veia do pênis de ratos, 20 mg/kg de peso corporal de "Evan's blue", e no tecido subcutâneo inoculou-se 0,1 ml de cada substância a ser analisada. Após intervalo de três horas os animais foram sacrificados, suas peles excisadas e recortadas com perfurador de 2,5 cm de diâmetro. As peças foram imersas imediatamente em oito ml de formamida e levadas ao banho-maria a 37ºC, por 72 horas, para remoção do corante. O líquido contendo o corante extravasado foi filtrado, analisado no espectrofotômetro (620 nm) e classificado segundo os critérios estabelecidos por Nagem-Filho, Pereira (1976). O potencial irritativo dos produtos, após análise estatística, se apresentou em ordem decrescente: Furacin (considerado como grau de magnitude severo) > Single Bond e Bond 1 (que se mostraram significamente similares, classificados como moderados) > soro fisiológico (comportando-se como não-significante quanto ao grau de irritação).

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