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

Objective: This investigation evaluated the leakage (diffusion) of lipopoly saccharide and dextran beneath cast-gold crowns luted with one of three cem ents. Method and materials: Thirty extracted molars were prepared for crown s. Thirty crowns with access ports (facial or lingual) were cast in gold an d luted to their preparations with zinc phosphate, glass-ionomer, or an adh esive resin cement (10 per group). Teeth and crowns with filters inserted i n the ports were immersed in a solution of labeled macromolecules (tetramet hylrhodamine isothiocyanate-labeled lipopolysaccharide and fluorescein isot hiocyanate-labeled-dextran) and evaluated for leakage at 2 weeks and 1, 2, 3, 4, 5, and 6 months. Filters were retrieved and analyzed with microfluori metry. Results: No filters retrieved from any crowns demonstrated any detec table leakage, and all filters were negative for both dextran and lipopolys accharide for all evaluation periods. Conclusion: For the 6 months of this investigation, zinc phosphate, glass-ionomer, and adhesive resin cements we re equally effective at preventing leakage of detectable molecular concentr ations of lipopolysaccharide and dextran to the level of the access ports i n the absence of thermal or mechanical stress.