Biocompatibility of self and heat-cured acrylic resins

Abstract

Biocompatibility of restorative materials for temporary is of great importance for the stability of pe- riodontal health while the defini- tive prosthesis is being made. The aim of this paper was to determine, by means of a histological study in subcutaneous tissue of mice, the biocompatibility of 3 types of ma- terial: self-curing acrylic resins – Classico and Duralay, and a heat- curing one – Classico. The resins were manipulated according to the manufacturer’s instructions and placed on the back of each mouse immediately and 24 hours after manipulation. 24 CF1 female mice were used, divided in 4 experimen- tal periods: 7, 14, 21 and 28 days. Three resin pieces were placed on the back of each mouse, one of each type. After the determined time period, sacrifice took place, the pieces were extracted, fixed, cut and colored with hematoxilin- eosin. The slides were evaluated under an optical microscope, and quantification of fibroblasts and inflammatory cells was performed, in 5 visual fields with 100X mag- nification, selected adjacent to the material. Intra-group comparisons were made by means of t-test (alpha = 0.05). Inter-group comparisons were performed by Anova (alpha = 0.05). The microscopic analysis revealed the tendency of fibrosis around the materials with decre- ase of inflammatory cells with time. The results did not indicate statistically significant differences between the resins, in each expe- rimental period, except for: a) the quantification of fibroblasts reve- aled, after 7 days, a higher mean value of fibroblasts around Duralay resin; b) when inflammatory cells are taken into account, a higher mean value of them was observed adjacent to the thermally activated resin. It may be concluded that the three resins present similar levels of biocompatibility when manipu- lated according to the instructions, making possible to think that other characteristics, other than biocom- patibility, also have to be taken into consideration when temporary restorations are the issue. Key words: acrylic resins, mo- nomer, methyl methacrylate, mice, biocompatibility.