A Study on the Applications of the Enamel Disk: Part 1. The Enamel Disk Molding Method and Physical Properties of an Enamel Disk

Extracted teeth are not suitable for many experiments, for example, regarding enamel solubility and plaque adhesion, because they have no reproducibility. So it is necessary to make a test piece that closely resembles enamel, is uniform, and applicable to such experimentation. The enamel disk molding method is as follows. 1) Thoroughly mix 325 mesh enamel powder refined from many extracted teeth with polymer solution. 2) Dry and pulverise it to 250 mesh. 3) Take 200 mg of 250 mesh powder and fill a metal mold with it. 4) Press it with a pressure of 18 ton/cm2. The enamel powder is reduced to an enamel disk which is from 0.7 to 1.0 mm in thickness and 13 mm in diameter. Polymer solution of polymethyl methacrylate (PMMA), epoxy (EP), or polystyrene (PS) can be used to mold an enamel disk. The concentration of polymer solution can be 10%, 20%, or 30%. A 10% PMMA-enamel disk is better than any others judging from its handling and attributes. It specific gravity of 2.27±0.07, a Vickers hardness number of 79.80±4.47 and a strength of rupture in bending of 0.928±0.059. The coefficients of variation of the Vickers hardness number and strength of rupture in bending are relatively small, 5.60% and 6.36%, respectively, in five-time repetitive tests. The purpose of this study, to get a uniform test piece, was achieved.