陶瓷假牙的材料发展.pptVIP

CONTENTS Introduction History Glass infiltrated alumina Incerams Procera all ceram Pressable ceramics Machinable ceramics CAD CAM HISTORY Since the stone age ceramics have been important for humans. 1789-de_chemant Duchateau. 1822-baking process. 1825-commercial production by Stockton. 1903-Dr.Charles Land-first ceramic crown 1962-Patents by weinstien and wenstein. 1965-Mclean Hughes CLASSIFICATION WHY DO WE NEED ADVANCED PRODUCTS ??? One of the most serious drawbacks with the early dental porcelains were their lack of strength and toughness, which seriously limited their use. In order to overcome these problems, there are two possible solution. One solution is to provide the dental porcelain with support from a stronger substructure. The other option is to produce ceramics, which are stronger and tougher. Metal free ceramic systems All ceramic systems can provide better esthetics. Wide range of tranlucency opacities are available Soft tissue health No over contouring Glass infiltrated alumina In-ceram alumina Supplied as one of the three core ceramics. 1)in-ceram spinell 2)in-ceram alumina 3)in-ceram zirconia In - ceram A slurry of material is slip cast on porous refractory die and heated in a furnace to produce a partially sineterd coping. This coping is infiltrated with glass at temp1100*c -4hrs In-ceram alumina Indication-anterior and posterior crowns and anterior 3-unit FPDs. Flexuarl strength-500mPa The final ICA core consists of 70wt% alumina and 30wt%sodiumlnathanum glass. Advantages Moderately high flexural strength and fracture resistance. A metal free structure An ability to be used succesfully with conventional luting cements Drawbacks Marginal seal is not as good as procera-all ceram or IPS Empress. High degree of opacity Inability to be etched Technique sensitive In ceram spinnel Indications-anterior single unit creowna,inlays,onlays veneers. It is the most translucent among the three . It was introduced as an aletrnative to ICA Improved