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

STATEMENT OF PROBLEM: Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials such as lipopolysaccharides (LPSs) or cell wall materials that have been shown to provoke inflammatory reactions in the dental pulp. PURPOSE: This investigation evaluated the leakage (diffusion) of fluorescently labeled LPS and dextran beneath cast-gold crowns luted with 3 cements. MATERIAL AND METHODS: Thirty extracted molars were prepared for crowns. Ten 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 immersed in a solution of labeled macromolecules (TRITC-LPS, FITC-dextran) and 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 periods. CONCLUSION: For the 24 months of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of LPS and dextran to the level of the access ports.

Macromolecular leakage beneath complete cast crowns. A 6-month in vitro investigation using microfluorimetry.

OBJECTIVE: This investigation evaluated the leakage (diffusion) of lipopolysaccharide and dextran beneath cast-gold crowns luted with one of three cements. METHOD AND MATERIALS: Thirty extracted molars were prepared for crowns. Thirty crowns with access ports (facial or lingual) were cast in gold and luted to their preparations with zinc phosphate, glass-ionomer, or an adhesive resin cement (10 per group). Teeth and crowns with filters inserted in the ports were immersed in a solution of labeled macromolecules (tetramethylrhodamine isothiocyanate-labeled lipopolysaccharide and fluorescein isothiocyanate-labeled-dextran) and evaluated for leakage at 2 weeks and 1, 2, 3, 4, 5, and 6 months. Filters were retrieved and analyzed with microfluorimetry. RESULTS: No filters retrieved from any crowns demonstrated any detectable leakage, and all filters were negative for both dextran and lipopolysaccharide for all evaluation periods. CONCLUSION: For the 6 months of this investigation, zinc phosphate, glass-ionomer, and adhesive resin cements were equally effective at preventing leakage of detectable molecular concentrations of lipopolysaccharide and dextran to the level of the access ports in the absence of thermal or mechanical stress.