EFEITO DA INCLUSÃO DE PARTÍCULAS DE CARGA NA RADIOPACIDADE E EM PROPRIEDADES DE SISTEMAS ADESIVOS EXPERIMENTAIS

Abstract

The aim of this study was to evaluate the radiopacity, ultimate tensile strength (UTS), microhardness (KHN), degree of conversion (DC), water sorption (WS), solubility (SO), microtensile bond strength (μTBS) and of experimental dental adhesives with increased addition of barium-borosilicate zirconia nanoparticles or glass microparticles. Methods: Ten experimental adhesive systems with different concentrations of zirconia nanoparticles [0(EX0), 15(EX15), 25(EX25), 35(EX35) and 50%(EX50) and barium-borosilicate oxide microparticles [0(R0), 30(R30), 40(R40), 50(R50) e 60%(R60)] were formulated based on the adhesive system Ambar (FGM). The adhesive Adper Single BondTM 2 (SB, 3M ESPE) was used as commercial reference. For the radiopacity (n=5), KHN (n=5), WS (n=10) and SO (n=10) tests, adhesive specimens were constructed using a stainless steel mold (5.0 mm in diameter and 1.0 mm in deep), while for UTS (n=5), a hourglass shape metallic matrix (10 mm long, 2 mm wide, and 1 mm deep with cross-sectional area of 0.8 mm2) was employed.The FTIR spectra of uncured and cured specimens of adhesives were used to determine the DC of the materials. For μTBS, adhesives were applied to flat dentin surfaces of third molars (n=7). Resin composite buildups were constructed and sectioned to obtain resin-dentin bonded sticks to tested immediately (IM) or after 6 months (6M) of water storage. Data were submitted to a one-way ANOVA and Tukey´s test (α=0.05). Results: All experimental bonding adhesives showed radiopacity similar to enamel. Only R60 showed higher UTS than the other materials. The experimental adhesives showed higher KHN values when compared to the commercial SB. In general, the DC of the experimental solutions was not affected by filler addition and was statistically higher than SB. Although filler addition did not affect WS, it generally reduced the SO. Most of the experimental adhesives showed lower WS and SO than SB. Conclusions: Both the addition of nanoparticles as microparticles were able to confer radiopacity to adhesives experimental, and adding load influence on the properties tested. In general, it can be said that the best performance was for the addition of microparticles in a concentration of 30%.