The Influence of the Operating Positions on the Prepared Abutment Contour of Full Cast Crowns: The Unanatomical artificial teeth for Fixed Bridge

With a view to research the effect of the crown form, we made the unanatomical artificial teeth and some doctors to do the abutment tooth preparation with full cast crowns for the maxillar left fixed prosthodontics three-unit bridge in random position. After that, following are the results of a study made on the influence to the prepared tooth form. The prepared teeth are the second premolar and the second molar (The “second premolar” is abbreviated to “5” and the “second molar” is abbreviated to “7”). 1. The reductions of occlusal surface was excessively larger at 5 and 7 buccal cusp regions, while it was excessively smaller at central groove area. 2. The reductions of axial surface and subgingival area were excessively smaller at 5 and 7. 3. As for the degree of axial taper, its was steeper toward the buccal and distal surfaces at 5 and 7. 4. As for the relative degree of axial taper, it get the largest in degree on both sides between 5 medial surface and 7 distal surface. The results of this experiment are similar to the results that used anatomical artificial teeth. These results are affected by the operating posture.