Macromolecular leakage beneath full cast crowns: A two-year in vitro investigation

Statement of problem, Most microleakage studies have used low molecular wei ght dyes or isotopes rather than clinically relevant materials such as lipo polysaccharides (LPSs) or cell wall materials that have been shown to provo ke inflammatory reactions in the dental pulp. Purpose. This investigation evaluated the leakage (diffusion) of fluorescen tly labeled LPS and dextran beneath cast-gold crowns luted with 3 cements. Material and methods. Thirty extracted molars were prepared for crowns. Tel l crowns with access ports (facial or lingual) were cast in gold and luted with zinc phosphate, glass ionomer, and an adhesive resin cement onto their preparations. Teeth and crowns with filters inserted into the ports were i mmersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) a nd evaluated for leakage every month for 24 months. Filters were retrieved and analyzed with fluorescent microscopy. Results. All filters retrieved from crowns luted with zinc phosphate, glass ionomer, and adhesive resin cements demonstrated no detectable leakage and were negative for both FITC-dextran and TRITC-LPS for all evaluation perio ds. Conclusion. For the 24 months of this investigation, zinc phosphate, Ketac- Cem, and C&B-Metabond were equally effective at preventing leakage of detec table molecular concentrations of LPS and dextran to the level of the acces s ports.