Production and characterization of dental porcelain

SUMMARY: PRODUCTION AND CHARACTERISATION OF DENTAL PORCELAIN Key words; Dental, porcelain, production Porcelain is one of the most important material used in dentistry since it obtains high strenght, high wear resist and the most esthetic. Porcelain exhibits excellent chemical qualities, becauselt is insoluble in the normal fluids and in practically any given food or drink. It is also chemically able to resist the acids or alkali frequently used for washing teeth. Moreover, mammalian tissues are very tolerant of its presence. Porcelain does have, however, some disadvantages: Long working time is needed. It is relatively fragile and repairs are difficult. It is costly. Because of berry fragile, artifical dental crowns and bridges have been made by using a metallic framework coated with a fused dental porcelain to provide the desired esthetics and strength. PFM estorations are fabricated by applying dental porcelain powder in aquueous slurry to a metal alloy framework.Then firing the porcelain at high temperature to form a tight, impervious porcelain layer having the appearance of natural dentition. Firing temperature of the porcelain must be at least 100 °C below the solidus temperature of the alloy used as the metal framework, to prevent melting or distortion of the metal framework during porcelain firing. It is further important that the coefficent of thermal expantion of the porcelain must be only slightly less than that of the metal so that no cracs are produced in the porcelain layer due to thermal expantion mismatch stress occuring during firing and cooling down. In this study, high strenght and low fusing dental porcelain is produced for use in metal-ceramic systems. For this purpose, dental porcelain powder has been produced by applying determined processes on the raw material of dental porcelain. Melting behaviour of this porcelain has been investigated by heat microscope. Mechanical tests were applied on the dental porcelain. Thermal expantion of this porcelain has been investigated by dilatometer. Phases of the dental porcelain has been investigated by XRD. Then, porcelain teeth with metallic framework is fabricated by applying porcelain powder on a metal framework. Porosite, surface hardness and alcali and acid resistance tests were applied on the porcelain teeth. xui