Heat-Shock Protein Expression as a Measure of Dental Materials Biocompatibility

Objective: The most frequent measures of dental materials biocompatibility are cell survival and cell death assays. Heat-shock protein (HSP) expression may have the potential to be used as a marker of non-lethal cell injury. The purpose of this study was to measure the HSP responses of cells within human dental pulp tissues in response to the presence of common dental materials. Methods: The following common types of dental materials; Calcium hydroxide [CH] (Dycal, Dentsply, Milford, DE), Composite Resin [CR] (One Step, Bisco, Schaumburg, IL), Zinc Oxide Eugenol [ZOE] (Kalzinol, Dentsply, Milford, DE) and Resin-Modified Glass Ionomer [RMGI] (Vitremer, 3M ESPE, St. Paul, MN) were aseptically packed into teflon tubing cut into 1mm pellets with a fixed volume of 2mm. The pellets were placed in contact with freshly extracted human teeth cut into 1mm slices (n=40) submerged in DMEM culture media containing 10% heat inactivated fetal calf serum and antibiotics for 2 or 7 days. Patients donated their extracted teeth following written informed consent. As a control measure, some tooth slices had no material added (n=10). After culture, the tooth tissues were processed for histology and biocompatibility according to ISO criteria. A biotin-streptavidin amplified immuno-detection kit was also used to detect HSP-70 antibody (NovoCastra, UK) binding within the pulp tissue. The data was analyzed with Kruskal-Wallis statistics. Results: In comparison with the control (untreated) tooth slice cultures, varying degrees of HSP-70 expression was observed according to the biocompatibility of the dental materials tested (P=0.0001). In rank order of HSP-70 expression, the dental materials from the most to the least, was; ZOE, CH, RMGI and CR. Conclusion: The expression of HSP-70 in human dental pulp tissues can be used as a non-lethal measure of the biocompatibility of dental materials. Research supported by NIH/NIDCR grant DE015573.