Francis F. Tung

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

STATEMENT OF PROBLEM Most microleakage studies have used low molecular weight dyes or isotopes rather than clinically relevant materials, such as lipopolysaccharides or cell wall materials, that have been shown to provoke inflammatory reactions in the dental pulp. PURPOSE This study evaluated the leakage (diffusion) of lipopolysaccharide and dextran beneath cast gold crowns luted with 3 cements. MATERIALS 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 at 2 weeks, and 1, 2, 3, 4, 5, and 6 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-lipopolysaccharide at all evaluation periods. CONCLUSION Leakage of lipopolysaccharides and dextran did not occur during the period of this study. For the length of this investigation, zinc phosphate, Ketac-Cem, and C&B-Metabond were equally effective at preventing leakage of detectable molecular concentrations of lipopolysaccharide and dextran to the level of the access ports.

A Technique to Verify or Correct Analogue Position and Soft Tissue Profile on an Implant Working Cast

A procedure which allows verification of the implant working cast and a method to correct the position of one or more implant analogues, if necessary, is described. In a single procedure, a corrected, accurate cast with soft tissue profile can be obtained by using a polyether impression material in conjunction with an acrylic resin jig. (J Prosthet Dent 2009;102:137-139).

Accurate procedure for simultaneous registration of gingival emergence profile and maximal intercuspal position for metal ceramic restorations

This article describes a procedure that simultaneously registers maximal intercuspal position and gingival emergence profile. The materials used in this procedure are inexpensive, readily available, and easy to use. The clinician can inspect the framework, cast, and tissue profile before sending them to the laboratory. When this method is properly used, it allows better communication with the dental technician, saves chair time, and reduces the number of laboratory procedures as currently practiced.

An alternative technique for fabrication of an occlusal device.

Several methods have been described for fabrication of occlusal devices, but many require complex and time-consuming laboratory procedures. In this article, an alternative fabrication method for a hard occlusal device while maintaining the articulation of the cast is described.