[Application of electroforming for coronal restorations. Metal frame for porcelain fused to metal crowns].

Today, it has been quite important to realize that the esthetic factor the coronal restration is more emphasized in dental practice. It is popular to use porcelain as a dental material for the Coronal restoration and the technique is pretty much stabilized. Because of the color itself and its great affinity to the human body. Mostly used technique is the porcelain fused-to metal crown. However, there are various disadvantages relating to this technique. On the other hand. The electroforming technique has some great characteristics that is producing the complex shape with less difficulty, and the improvement of it's final surface. It also has the ability for reduplication. Overall, metal frame can be constracted on the same working model without a duplication of it. Therefore, it is possible to make the procedure extremely simple. Here, the author has done some experiments with the newly developed electroforming apparatus for constructing the Coronal restoration. The purpose of the experiments are to apply all these great advantages of the system to dental prosthodontics field. One characteristic of the equipment is the diffusion of current distribution by the cathode rotary system. The other one is the circulation of electrolyte for reducing the diffusion layer. Firstly, the author operated the electroposition with Ni on the three different standard models of abutment teeth, in order to determine the possibility of making a metal frame and the relationship between the shape of the abutment teeth and the current. Next experiment was to investigate if it's possible to apply the metal frame, constructed by the apparatus, to porcelain fused-to metal crown by again determining the relationship between the electropositioned metal and the porcelain. The results were obtained as follows. 1. It was possible to construct a metal frame for the porcelain fused-to metal crown by the method. 2. The minimum electroposition time was approximately 35-40 min. with a high current density. 3. The thickness of the metal frame did not effect the current, however it barely effected the shape of the abutment teeth. 4. The tensile strength by shear was approximately 150 kg/cm2. 5. There was no evident that the current has any effects on tensile strength.