Cytotoxicity Comparison of Harvard Zinc Phosphate Cement Versus Panavia F2 and Rely X Plus Resin Cements on Rat L929-fibroblasts

Objective: Resin cements, regardless of their biocompatibility, have been widely used in restorative dentistry during the recent years. These cements contain hydroxy ethyl meth- acrylate (HEMA) molecules which are claimed to penetrate into dentinal tubules and may affect dental pulp. Since tooth preparation for metal ceramic restorations involves a large surface of the tooth, cytotoxicity of these cements would be more important in fixed pros- thodontic treatments. The purpose of this study was to compare the cytotoxicity of two resin cements (Panavia F2 and Rely X Plus) versus zinc phosphate cement (Harvard) using rat L929-fibroblasts in vitro. Materials and Methods: In this experimental study, ninety hollow glass cylinders (internal diameter 5-mm, height 2-mm) were made and divided into three groups. Each group was filled with one of three experimental cements; Harvard Zinc Phosphate cement, Panavia F2 resin cement and Rely X Plus resin cement. L929- Fibroblast were passaged and sub- sequently cultured in 6-well plates of 5×105 cells each. The culture medium was RPMI_ 1640. All samples were incubated in CO . Using enzyme-linked immune-sorbent assay (ELISA) and (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) (MTT) assay, the cytotoxicity of the cements was investigated at 1 hour, 24 hours and one week post ex- posure. Statistical analyses were performed via two-way ANOVA and honestly significant difference (HSD) Tukey tests. Results: This study revealed significant differences between the three cements at the differ- ent time intervals. Harvard cement displayed the greatest cytotoxicity at all three intervals. After 1 hour Panavia F2 showed the next greatest cytotoxicity, but after 24-hours and one- week intervals Rely X Plus showed the next greatest cytotoxicity. The results further showed that cytotoxicity decreased significantly in the Panavia F2 group with time (p < 0.005), cyto- toxicity increased significantly in the Rely X Plus group with time (p < 0.001), and the Harvard cement group failed to showed no noticeable change in cytotoxicity with time. Conclusion: Although this study has limitations, it provides evidence that Harvard zinc phosphate cement is the most cytotoxic product and Panavia F2 appears to be the least cytotoxic cement over time.