Studies on Fit of Castable Apatite Ceramic Crowns. The Influence of Factors on Investing and Burnout.

The influence of various factors on dimensional changes and surface roughness in the interior of castable apatite ceramic crowns (CACC) was investigated. The influence of concentrationof colloidal silica liquid (liquid concentration) and cement on fit in CACC was also investigated, and the marginal fit in CACC and castable mica-crystal ceramic crown (mica-crystal crown) wascompared.The following results were obtained.1. Dimensional changes and surface roughness in CACC were significantly influenced by L/Pratio and liquid concentration.2. A significant correlation was observed between liquid concentration and dimensionalchanges, surface roughness in CACC.3. The setting expansion in CACC investment increased with increases in the liquid concentration, while there was little change of thermal expansion.4. Cement film thickness at margin of CACC decreased with increases in the liquid concentration i. e. the marginal fit in CACC was significantly influenced by the liquid concentration.5. The marginal fit in CACC and mica-crystal crown was clinically acceptable, and themarginal fit of CACC was better than that of mica-crystal crown.