前ろう着法による陶材焼付金属冠ブリッジの技工操作過程における変位

抄録

The author, conducted the following studies in order to clarify the causes of displacements and distortions in the ceramometal fixed partial prosthodontics (bridge) using the pre-solderd joint that occur during the laboratory procedure. In conducting these studies, the author assembled a ceramometal fixed bridge consisting of 8 units with a canine and a first premolar on either side in the maxillaserving as the abutment, for the portion in which four teeth-the central incisors and lateral incisors on both sides-were missing. Then, in order to find out when the framework of the fixed bridge was displaced or distorted and what the extent and direction of such displacements or distortions were, three-dimentional deviations of the framework were measured. As a result of these studies, the following conclusions were reached;
1. Throughout the laboratory procedure, it was at the time of pre-soldering and degassing that a substantial displacement ofthe fixed bridge was noted. Some displacement, although a minor one, was found at the time of the firing of body-incisor porcelain and that of glazing, too. However, no significant displacement was noted at the time of surface-grinding and that of the firing of opaque porcelain.
2. As to the displacement at the time of pre-soldering, the distortion of the soldered body (the portion made with one-piece cast method) itself was minimal; a kind of displacement was seen where the curve of the fixed bridge closed mainly as a result of two soldered bodies coming close to each other.
3. At the time of degassing, the curve of the fixed bridge opend wide as a result of the distortion in the portion made with one-piece cast method and the displacement at the soldered portion.