In vitro biocompatibility of novel fluoride-releasing monomers and materials

Objectives: to evaluate the in vitro cytotoxicity of novel chelating dental monomers, fluoride-releasing monomers, and experimental fluoride-releasing composite and adhesive. Methods: two synthesized chelating monomers (M1 and M2), two fluoride-releasing monomers (M3 and M4) and their corresponding experimental composite and adhesive were tested for relative cytotoxicity in vitro. 0.1 vol% sterile DMSO in medium was used as solvent. The concentration of monomer M1-M4 in medium was from 1× 10^-4 to 1× 10^-7 mol/L. The leachants from the cured composite and adhesive were diluted from neat to 1:1000. The percent survival versus control (PSVC) of the cell was measured using the standard WST-1 assay responded by three cell lines with increasing sensitivity: L929 - murine fibroblast, 6G3-immortalized murine odontoblast, and 10H1- immortalized murine pulp cells. Culture medium was used as negative control and BisGMA at 10^-4 mol/L as positive control (PSVC=0). The data were analyzed using ANOVA and post hoc tests (p=0.05).

Results: PSVC of six test specimens at 10^-4 mol/L or original leachant (mean±SD)

Cell lines	DMSO, 0.1%	M1	M2	M3	M4	Composite	Adhesive
L929	109.2±6.5	99.9±12.1	97.3±6.5	90.5±2.2	112.1±10.4	102.2±4.2	93.6±9.9
MO6-G3	100.7±8.3	96.9±17.8	70.1±5.3	14.5±4.8	84.0±12.7	92.9±5.9	36.4±11.1
MD10-H1	102.9±10.1	89.2±17.6	71.7±10.1	6.4±11.1	77.2±12.5	101.6±1.2	53.9±11.1

Monomer M1-M4, the fluoride-releasing composite and adhesive have no significant cytotoxicity to murine fibroblast L929 cells. On both odontoblast and pulp cells, M2-M3 (1×10^-4 mol/L) and adhesive (neat leachant) showed significantly higher cytotoxicity than negative control (p<0.05) but they are still less toxic than BisGMA (1×10^-4 mol/L). M1 and the composite showed little cytotoxicity on all three cell lines. Conclusion: The novel chelating monomers, fluoride-releasing monomers and fluoride-releasing composite and adhesive demonstrated significantly less cytotoxicity than BisGMA. Therefore, they may be suitable for use in dental restoration. Supported by the Brown Foundation and NIH/NCRR-COBRE grant (P20RR020160-1).