Avaliação da resistencia a microtração de sistemas adesivos, utilizando-se, como pre-tratamento, concentrações e tempos de aplicação de hipoclorito de sodio

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The aim of this in vitro study was to evaluate the tensile bond strength of adhesive systems to dentin, with three concentrations (1 %, 5%, and 10%) and application time (15, 30 and 60s) of sodium hypochlorite (NaOCI) solution, as dentin pre-treatment. Three hundred bovine teeth were selected and stored in a 0.9% saline solution with thymol. The buccal surface was flat grounded and the dentim surface was polished (Politriz -Maxigrind Solotest), with 180, 400 and 600 grit Aluminium oxide (AI203) abrasive paper. The teeth were randomly allocated to 20 groups and treated with Gluma Comfort Bond and Bond One. G1 to G10 were applied Gluma Comfort Bond and G 11 to G20 were applied Bond One (n= 15), according to manufactures instructions. Groups G1 and G11 were considered control groups. After the etching, 1 % NaOCI solution was used for G2, G3, G4, G12, G13 and G14, during 15,30 and 60s, respectively. For the groups G5, G6, G7, G15, G16 and G17, 5% NaOCI solution was used during 15, 30 and 60s, respectively, and for G8, G9, G10, G18, G19 and G20, 10% NaOCI solution was used during 15, 30 and 60s, respectively. The specimens were restored with the Filtek Z-250 (3M Dental Products), building a flat crown. This composite resin was applied to three increments and light cured for 40s each. The teeth were sectioned with a slow-speed diamond saw, obtaining slices ranging from 0.7-1 mm in thickness. The slices were trimmed and shaped to hourglass form (0.7-1 mm2 bonded surface area). These specimens were submitted to tensile load at a cross head speed of O.5mm/min. The data were analyzed by ANOVA, using a post hoc test interations 2x3x3, plus two additional treatments. No statistical difference was observed between the adhesive systems and different concentrations. However, statisticaJly significant difference was observed for application time. The increase in the application time resulted in a decrease in the bond strength values (p=O,00016). In conclusion, the application of different NaOCI concentrations did not improve the bond strength values; however, the increase in the application time interfered negatively with the tensile bond strength when NaOCI was used

ASSUNTO(S)

resinas compostas dentina adesão materiais dentarios

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