THE EFFECT OF SPIROORTHOCARBONATE VOLUME MODIFIER CO-MONOMERS ON THE IN-VITRO TOXICOLOGY OF TRIAL NON-SHRINKING DENTAL EPOXY COPOLYMERS

A major improvement in dental restoratives is possible through the dev elopment of biomaterials that do not shrink upon polymerization, hence , avoid leakage and subsequent breakdown. Polymers containing spiroort hocarbonates (SOCs) show promise in this respect, but their toxicology in copolymerized materials has not been explored. In this study, the in vitro toxicology of these materials in homopolymer form and in two trial non-shrinking epoxy co-polymers was evaluated for cytotoxicity a nd mutagenicity. Cytotoxicity was determined by the MTT test to measur e the lethality effect on mouse L929 cells. Mutagenicity was evaluated using the Ames-Salmonella Test. For comparison, commercial composite and adhesive materials as well as several other materials of current i nterest in dentistry were also evaluated. Epoxy resin samples containi ng 5% of either T/T SOC or Dp SOC reduced the cytotoxicity (TC50) from approximately 400 to 800 mu g/200 mu l. The epoxy-spiro copolymers ha d more favorable TC50 values than the commercial product Super-Bond. T hey showed TC50 values on the order of 35% greater than Super-Bond and 45% less than Scotchbond 2, the latter two being materials currently used in the clinic. These two comparatives demonstrated dose response curves with lower doses at maximum cell kill values than the spiro mat erials. The epoxy formulations all showed weak mutagenesis, but this i s attributed to the epoxy formulation and not the SOCs. Although consi derable toxicology is yet be conducted, these in vitro results suggest that biocompatible copolymer formulations for spiroorthocarbonates ar e a developmental reality.