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Dental Science Popularization: Porcelain Fused Teeth
1、 Concepts
Porcelain fused to metal crowns, also known as metal ceramic crowns. It is a full crown restoration formed by high-temperature sintering and melting of ceramic powder onto the surface of the metal inner crown. Metal ceramic crowns are currently the most commonly used full crown restorations in clinical practice, combining the advantages of good mechanical strength of cast metal crowns and aesthetic appearance of all ceramic crowns, making them an ideal restoration.
2、 Classification
Metal repair
Use metals such as silver mercury, gold alloy, and titanium alloy to make dental crowns.
Metal porcelain restoration
(1) Ordinary metal porcelain crowns: The main components of the internal crown are nickel chromium alloy (now phased out in most hospitals) and cobalt chromium alloy.
Advantage: Effectively solving the problems of high hardness and color fidelity of stainless steel crowns.
Disadvantages: In nickel chromium alloy, nickel is unstable and is prone to metal ions dissociation, resulting in a green gingival margin and a grayish color compared to real teeth;
Poor biocompatibility, some patients are metal sensitive, and their gums will permanently oxidize and turn black.
Difference: Cobalt chromium alloy does not contain nickel or beryllium, and its performance is relatively stable compared to nickel chromium alloy. However, the base color is a cold tone, and the porcelain crown is slightly gray.
(2) Precious metal porcelain crown: Using precious metal alloys such as gold platinum and gold palladium as the inner crown, with a surface porcelain.
Advantage:The color is realistic, difficult to distinguish true from false with the naked eye, with excellent performance in all aspects and good biocompatibility.
Shortcoming:Metal ceramic restorations will lose their transparency and appear dead white under special lighting conditions such as ballroom fluorescent lights and strong ultraviolet rays.
3. All ceramic restoration
(1) Cast porcelain crowns
Advantages: All ceramic restorations have a perfect appearance, color, and are almost indistinguishable from real teeth. They also have excellent biocompatibility and almost no rejection reactions.
Disadvantages: The compressive and flexural strength are lower than those of metal ceramic restorations.
(2) Zirconia all ceramic crown
Advantages: Perfect appearance, color, biocompatibility, precision, and strength close to metal porcelain.
Disadvantage: The strength is slightly lower than that of metal ceramic restorations.
