Dental Materials Biocompatibility Measured using Heat-Shock Protein Expression

Objective: The purpose of this study was to measure the heat shock protein (HSP) responses of cells within rodent dental pulp tissues in response to the presence of common dental materials. Dental pulp biocompatibility testing is necessary to ensure that dental materials have a minimal potential to damage the vitality of teeth. HSP-70 expression may have the potential to serve as a measure of non-lethal cell injury. 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 28-day Wistar rat tooth slices (n=40) submerged in DMEM culture media containing 10% heat inactivated fetal calf serum and antibiotics for 2 or 10 days. 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 to pulpal tissue structures. 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: HSP-70 has the potential to be used as a biocompatibility marker of non-lethal dental pulp injury in response to dental materials. Research supported by NIH/NIDCR grant DE015573.