Macromolecular leakage beneath full cast crowns. Part I: The diffusion of lipopolysaccharide and dextran

Fifteen extracted molars were prepared for crowns. Crowns with access ports (one facial, one lingual) were cast in gold. Teeth and crowns with filters inserted into the ports were immersed in solutions of different concentrations of labeled and unlabeled macromolecules (fluorescein isothiocyanate-dextran, tetramethylrhodamine isothiocyanate-lipopolysaccharide [LPS], unlabeled LPS) and were evaluated for leakage. Retrieved filters were analyzed with fluorescent microscopy. At 10 micrograms/ml, only LPS leaked beneath the crowns in 24 hours (p = 0.0002), but after a 1-week immersion, both LPS and dextran leaked beneath the crowns. LPS scores were higher (p = 0.0002) than dextran scores. Slightly more LPS leakage occurred at 1 week than at 24 hours. LPS appeared to inhibit dextran diffusion beneath the cast crowns. Neither LPS nor dextran influenced LPS diffusion. Factors other than molecular size and weight may play a more important role in the microleakage occurring beneath crowns.