Cell Culture versus Tooth Culture for Dental Materials Biocompatibility Screening

Objective: The conventional approach to screen dental materials for biocompatibility is to use cell culture: The novel biocompatibility screening approach is to use tooth culture. The purpose of this study was to compare the biocompatibility screening of four common dental materials using both these in vitro assay types. Methods: The following 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 28-day rat incisor teeth cut into 1mm 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 teeth had no material added (n=10). After culture, the teeth were processed for histology and biocompatibility according to ISO criteria. Pellets of CH, CR, ZOE, and RMGI materials in Teflon tubing (n=40) were placed into confluent L929 cell cultures for 24 hours, and the neutral-red assay was used for biocompatibility screening. The data was analyzed with Kruskal-Wallis statistics. Results: In both the screening assays, varying degrees of dental materials biocompatibility was observed P<0.05). The most to the least biocompatible dental materials in both assays were CR, RMGI, CH and ZOE. Conclusion: Both in vitro screening assays provided similar biocompatibility assessments of the dental materials. The advantage of tooth culture is that it allowed the biocompatibility screening of dental materials on all dental-pulp cell populations using a single in vitro assay. Research supported by NIH/NIDCR grant DE015573.