Preparation And Characterization Of Machineable Polymer Infiltrated Ceramic For Dental Restoration

Computer-aided design/manufacturing (CAD/CAM) is currently gaining rapid popularity in dental restoration. However, traditional machinable materials like all-ceramic still experience a serious abrasion to natural teeth due to their inherent brittleness and relatively high modulus. Thus, it is necessary to develop novel machinable materials,which should have similar properties to natural teeth in targeting for long-term clinical restoration. To this end, machinable hybrid blocks composed of both resin component and ceramic component were designed and fabricated, in which, a kind of resin-infiltrated glass-ceramic interpenetrating network was obtained. Briefly, porous ceramic blocks were made from feldspar or barium glass-ceramic powder by pressing and partially sintering, followed by resin(BisGMA/TEGDMA) infiltration with the aid of vacuum. The main work is as follows:1. The sintering was optimized by changing temperature and time,and the optimized parameters for the preparation of porous ceramic were set as 755?/0min in preventing significant shrinkage and proper porosity(20-25%). The infiltration of resin into the porous ceramic was then optimized by changing the resin viscosity, the maintaining time of vacuum condition and repeating times of the vacuum infiltration.Obviously appropriate extension of the vacuum maintaining time and increasing the times of vacuum infiltration, were in favor of the complete infiltration of resin into the porous ceramics. It is recommended that the vacuum maintaining time is above 30 min and the times of vacuum infiltration is morer than three times. Meanwhile, The porous ceramic internal pores were modified with KH570, which is helpful to improve the interface compatibility between resin and ceramics and improve the mechanical strength. Finally, confirmed by various characterizations(flexural strength, Weibull modulus, flexural modulus, fracture toughness,Vickers hardness, Wear resistance, etc.), it was found the formation of the resin-infiltrated glass-ceramic interpenetrating network was perfect,showing excellent interfacial adhesion between the two phases. When the weight ratio of BisGMA / TEGDMA was 6: 4, flexural strength is 140-150MPa, Weibull modulus is 22.1(2.1), flexural modulus is 30(4)Gpa, fracture toughness is 1.64(0.12)Mpam1/2 , Vickers hardness is 5.2(1.3)Gpa, Wear resistance is 8.21(1.33)mm2, the blocks achieved mechanical properties resembling the natural teeth and low surface roughness, which enabled them to be CAD/CAM machined and used in dental restorations.2. The material needs to have a certain thickness for CAD/CAM.So the material thickness is increased to 12mm. The sintering temperature was reduced to 725 ?. Mechanical properties of the blocks with 12mm is similar to the result of before.3. Due to the high cost of feldspar powder, using barium glass powder to prepare the PICN material. The material has high transparency.Mechanical properties of barium glass is higher than feldspar material,which is closer to natural tooth.