Effect of naturally derived antioxidants as polymerization inhibitors on experimental adhesive resins

Abstract

This study aimed to evaluate the physico-mechanical and biological properties of experimental adhesive resins modified with different antioxidants as radical polymerization inhibitors. The adhesive resins were formulated by mixing BIS-GMA, TEGDMA and HEMA (mass ratio of 50/25/25 wt%) and a tertiary initiation system (CQ + EDAB + DPHIHF –molar concentration of 1 %, 2 % and 1 %, respectively) together. Different antioxidants were added (1 mol%) to aliquots of the experimental resin, as follows: BHT (Butylated hydroxytoluene); HQ (hydroquinone); QC (quercetin); GA (gallic acid); and AA (ascorbic acid). An unmodified resin was used as control. The resin adhesives were tested with regard to sensitivity to ambient light, degree of conversion, cohesive strength, yellowing index, color stability; in addition, translucence and cytotoxicity (MTT assay) were analyzed. The data were analyzed using ANOVA and Tukey post-hoc tests (α = 5 %). The control and AA-based adhesive failed in the sensitivity to ambient light test. Adhesives modified with BHT and AA showed lower DC than the others. Color was considerably changed for the QC-containing adhesive. The presence of QC in the adhesive resulted in a higher yellowing index. When compared with the control, the addition of GA resulted in a reduction of the cohesive strength of the materials. All adhesives demonstrated similar cell viability and translucency. The use of alternative antioxidants as polymerization inhibitors rather than the synthetic types traditionally used showed potential application for the formulation of novel dental adhesive resins without significant impairment of the biological and physico-mechanical performance of the material.