Efeito da adição de um inibidor de metaloproteinase sobre a resistência à microtração e citotoxicidade de um sistema adesivo autocondicionante

Abstract

The aim of this study was to investigate the effect of zinc methacrylate (ZM) as a matrix metalloproteinase2 (MMP- 2) inhibitor on the microtensile bond strength (μTBS) and cytotoxicity of a self etching adhesive system (Clearfil SE Bond – CSE). For mechanical test, the self-etching primer was modified with 1 or 5 % (wt) of ZM, while adhesive system served as control (CSE). Twenty-eight human third molars were randomly assigned into four groups (n=7 teeth per group): CSE, CSEZM1 and CSEZM5 were stored in distilled water and CSECHX was stored in 2% chlorhexidine digluconate. After restorative procedures, teeth were sectioned to obtain beams, stored at 37o C for 24 hour, 6 and 12 months. After, μTBS was measured. For cytotoxicity test, mouse fibroblasts (3T3/NIH) were exposed to extracts of three different primers (CSE, CSEZM1 and CSEZM5) for 12 and 24h. Medium DMEM (Dulbecco’s Modified Eagle’s Medium) as used as control. The cell was plated (2 x 104/well) in two 96 round-bottomed tissue culture plates. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to asses cell metabolic function by mitocondrial dehydrogenase activity. The absorption at 570nm was determined spectrophotometrically. Data of μTBS were analyzed by One-Way Anova and Tukey test ( =0.05). Control group show similar μTBS after storage times. The CSEZM5 disclosed a decrease of bond strength after six moth storage and statistically lower μTBS means when compared with control group (p<0.05) Cytotoxicity was analyzed using Kruskal-Wallis test and Sudent-Newmans- Keuls method. There was a reduction in cell viability after exposure in all tested groups when compared to the Control. However, cytotoxicity of CSEZM1 and CSEZM5 were lower than CSE. The addition of zinc methacrylate on self-etching primer or storage in chlorhexidine may negatively affect μTBS of CSE. However, cytotoxicity of the commercial primer may decreased with ZM addition.