Cast Glass, Ceramic Precision And All-ceramic Crown Marginal Adaptation

All-ceramic restorations are now gradually accepted by both doctors and patients not only because of their good aesthetic effects as well as superior physical and chemical properties, but also in their solving the problems of neck coloring, metallic depositing and metal-porcelain integrating which exist in porcelain-fused-to-metal (PFM) restorations. Now there are many various types of all-ceramic materials with their own distinct fabricating techniques both at home and abroad, and the physical and chemical properties are also different from each other. We chose three kinds of those all-ceramic materials, which are generally known as having super properties as In-ceram, Hi-ceram (VITA GERMANY) and Dicor (DENTSPLY U. S. A). Under strictly controlled experimental conditions, the fabricating procedures are accurately followed to make all-ceramic crowns on standardized moulds. Then we compared the adaptation of the crowns made of different materials. The purpose of this study is to evaluate the impact of distinct manufacturing procedures on the fit of the crowns, which in turn will select one kind of all-ceramic material with simpler fabricating procedures while better restorative effect is preserved at the same time. In this study we also compared the effect of using different casting mould materials on the fit of casting glass ceramic crowns, hoping that would provide the technicians' application of casting mould materials with some reference. The results are as below:1. Three kinds of casting mould materials (BLACK INLAY WAX SHANGHAI CHINA, 0.5mm MODEL SHEETS & INLAY WAX SHOFU JAPAN, DIASTOLIC WAX Heraeus U. S. A) are all fit for fabricating casting mould in casting glass ceramic crown manufacturing procedures.2. The restoration made with black inlay wax(Shanghai dental materal factory) as the wax pattern has the worst accuracy (marginal fit: 107.67 m);the restoration made with relax wax(Heraeus company Germany )and inlay wax(SHOFU company Japan) as the wax pattern has the best accuracy(marginal fit:90 m);the restoration made with 0.5mm MODELSHEETS and inlay wax(SHOFU company Japan) as the wax pattern has a accuracy(marginal fit:92.53 m) similar to the former one.which means both have superior accuracy.3. The edge accuracy meets the clinical demands (120nm) on all restorations fabricated with three types of all-ceramic restorative materials as In-ceram, Hi-ceram (VITA GERMANY) and Dicor (DENTSPLY U. S. A) respectively.4. In-ceram all-ceramic crown is superior both in adaptation as well as physical and chemical properties but has a more complicated manufacturing procedure than the crowns made of other two materials, while Dicor all-ceramic crown has the simplest manufacturing procedure among the three ones but its adaptation is inferior to those made of other two materials.