Use of Dentine Disks in Cytotoxicity Testing of Dental Materials

Objectives:There is a growing interest in the use of in vitro cytotoxicity assays for the evaluation of dental materials but complete standardization in methods used are still limited. Tyas first demonstrated the use of dentine as a barrier between cells and the test materials, in 1977. The choice of cell-line is important and it is suggested that pulp fibroblasts be used rather than for instance 3T3 mouse cells. Aim:The purpose of this study was to test a system, where dentine disks are used as a barrier by investigating the growth of a human pulp cell-line directly on the disks and comparing these to the growth of an established Balb/c 3T3 mouse cell-line. Materials and Method: Dentine disks of approximately 0.5mm thick were derived from third molars. Balb/c 3T3 and pulp fibroblasts were grown in a 5.0% humidified atmosphere at 37 0 C in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum and P/S. Near confluent cells of both types were trypsinised and plated out evenly on the dentine disks. Cells were grown for 24 hrs, the disks removed, placed in well plates and the MTT test was undertaken to indicate the number of viable cells. Spectrophotometer absorbance at 540 nm was then measured and compared with those of the controls using ANOVA at a 95% confidence level. Results: It was found that the function of growth was higher for the 3T3 cells than for human pulpal cells. However, the dispersion, as measured by the interquartile range, and the standard deviation of the human pulp cells was significantly less than for the 3T3 cells. Conclusions: It is suggested that pulp cells be used. The standardization of an in vitro system of biocompatibility testing that includes dentine and pulp cells should improve the correlation between laboratory and clinical results.