이중관 국소의치의 외관 제작기법에 관한 고찰 = Evaluation of outer crown fabrication methods for double crown retained removable partial denture

다국어 초록 (Multilingual Abstract)

Purpose: The purpose of this study was to investigate clinical usability of the outer crown fabrication methods for double crown retained RPD.
Method: Three inner crowns with cone angles of 2 degrees, made of Co-Cr alloys, were prepared. According to different fabrication methods for outer crown, such as lost-wax, cast-on, and electroformed technique, three different outer crowns were fabricated. Using the universal testing machine (Tinius Olsen 1000, Tinius Olsen, USA), inner and outer crowns were connected under 5kgf, invested into clear resin blocκ half sectioned along the long axis of specimens and examined under light microscope.
Results: Under the conditions of this study, the following conclusions were drawn:
1. The fitness between inner and outer crown using lost-wax technique was the poorest. Multiple casting porosity were observed at inside of the outer crown.
2. The inner and outer crown using cast-on technique were fused together. It is very difficult to find gap between the crowns and to remove inner crown from outer crown.
3. The electroformed outer crown was fabricated directly on the inner crown by using electroforming machine and showed very precise, even space between inner and outer crown.
Conclusion: Under the conditions of this study, the electroforming system was the best method for the fabrication of outer crown of double crown retained RPD.