The Properties And Color Of Alumina Glass For Dental CAD/CAM

With the rapid development of the computer industry, dental CAD/CAM technique become more popular in clinical use. But the research on machinable ceramics were relatively slow because of their lower tensile strength, high brittle and bad cutting properties. Lots of studi es-~~how that porous aluminum oxide cores were made by CAD/CAM system, this porous structure is subsequently infiltrated with molten glass, then the structure were veneered with Vita porcelain to obtain a desired shape and color. This procedure combined In-Ceram technique and CAD/CAM technique, it offered a new way to fabricate all ceramic restorations. however, the veneering program make this technique more complicated. In this study, a partially-sintered, porous alumina block for dental CAD/CAM made of high-purity, fine a -alumina power was shaped by isostastic pressure and sintered at high-speed to temperature of 1450 t. After milling the alumina block for a full crown, melt infiltration should be proceeded with special self-made lanthanum borosilicate glass with different colors to form the final alumina梘lass梒omposite crown. To find and confirm the most effective preparing technology, the effect of sintering temperature and calefactive velocity upon mechanical properties and microstructures Qf the materials before and after infiltration were studied. In order to control the coefficient of thermal --3-- expansion arid colors of the glass as well as the fluidity and infiltration property of the melted glass, we modified the formula of the glass. Moreover, the biological evaluation of the alumina梘lass-composite was made to ensure the clinical security and reliability of the material. By milling the alumina block with Cerec II CAD/CAM equipment and then infiltrating it with different colors lanthanum borosilicate glass, high-strength, all-alumina-ceramic crowns were fabricated and evaluated in clinical use .The following results were obtained: 1. Among the materials sintering under different temperature and calefactive velocity, the alumina block sintered at high梥peed to 1450 cc were the best in mechanical properties and cutting properties. 2. Density, three-point bending strength, fracture toughness, modulus of elasticity and cutting properties of partially梥intered alumina block sintered at high-speed to 1450CC were 2.79g/cm3, 16OMPa, 2.llMPam? , 121MPa and 1.04 j.~m4 respectively. 3. CeO2 and Fe~O3 can be added to modify the color of the infiltration glass. 4. Density, Vicker抯 hardness, coefficient of thermal expansion, three-point bending strength, fracture toughness and modulus of elasticity of the infiltration glass were 2.l9g/cm3. 7.84GPa~ 6.8 x106 慍1~ 118 MPa-. 1.23MPam?-. 98MPa respectively. 5. Density, Vicker抯 hardness, co-efficient of thermal expansion, three-point bending strength, fracture toughness and modulus of elasticity of the alumina-glass-composite sintered at high-speed to 1450 CC were3.889g/cm3~ l0.9lGPa~ 8.lxl06t4~ 422MPa~ 4.59MPam敀2.~, 268MPa respectively. 6. As their value,26 shades of VI...