オールセラミッククラウンの適合に関する研究 ステイニング法の製作工程における適合状態

Abstract

This study was conducted to investigate how the ideal marginal fit of wax crown changes through the injecting, staining, glazing, and cementing procedures during fabrication of the IPS Empress crownby the staining technique for the upper first premolar tooth of the Dental Study Model (500 A, NISSIN DENTAL PRODUCTS, Japan). The vertical and horizontal gaps were measured by a scanning laser microscope system at identical measuring points in each fabrication step. The thickness of the cement film in the marginal area was also measured using sectioned specimens, both faciolingually and mesiodistally.The conclusions were as follows:1. The state of marginal fit at the As-Press stage was Open-Extra. The Open (vertical gap) was in the range of 27.5-30.5μm, and the Extra (horizontal gap) was 30.1-39.1μm.2. The rate of change of the vertical gap due to the shrinkage of ceramics at the first firing (Stain 1) was significantly greater than that at each subsequent firing step. This change accounted for 60-70% of the total. No significant difference was observed for the horizontal gap between steps.3. The rate of change of the gaps at each subsequent firing step (Stain 2, Glaze 1 and 2) was small, and there was no significant difference between firing steps.4. The state of the marginal fit of finished crowns was still Open-Extra. The Open (vertical gap) was in the range of 38.2-45.3μm, and the Extra (horizontal gap) was 20.3-30.8μm.5. The cement film thickness at the shoulder was similar to the amount of vertical gap at the final firing step (Glaze 2), in the range of 28.7-33.1μm.