A study on the development of paste porcelain

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In the year 1999, fundamental properties of this paste porcelain were tested according to ISO6872 : 1995 and the results were presented at 78^<th> General Session ＆ Exhibition of the IADR in Washington D,C. in April 6, 2000. The average flexural strength for paste porcelain was 109.3±8.5 MPa, which was significantly higher than that for conventional powder porcelain, G-Cera ORBIT, whose value was 88.6±7.7MPa. The result of chemical solubility test after refluxing 16hours in 4% acetic acid was 21.8μg/cm^2, which was within the range of 100μg/cm^2(max). In the year 2000, we continued to improve the quality of paste porcelain according the advices from the co-operative researcher, Dr. Tsuchihira, who is the senior lecturer of the school for dental technicians. In the final year, the bond strengths were tested according to ISO/FDIS 9693 : 1999, Metal Ceramic Dental Restorative Systems. The average bond strength measured for paste porcelain was different according to the alloy used, which were 54.3±3.8MPa (MC70) and 43.7±5. 1 MPa(D.U.) respectively. They were similar or slightly higher than that for conventional powder porcelain. These results will be shown at the 80^<th> General Session ＆ Exhibition of the IADR(March6-9) in San Diego.(Problems to be solved in the future)1. When used for a single crown, there is no problem ; however, in case used for a fixed partial denture, detachments and the crack may happen because of the large amount of paste porcelain.2. A pre-firing drying furnace (which can raise the temperature till 300℃ and has the ventilation function)is thought to be essential to keep the air clean and to protect the conventional porcelain furnace.