It is a typical non precious metal porcelain tooth. Porcelain fused to metal (PFM) is an advanced technique for dental inlay. It has the advantages of beauty, naturalness, firmness and wear resistance. It is a favorite product for many patients with dental diseases. So what is the composition of cobalt chrome porcelain teeth? Generally, chromium is not less than 25%, molybdenum is not less than 4%, and the total of cobalt, nickel and chromium is not less than 85%. There are different opinions about the quality of cobalt chromium alloy porcelain teeth. Some people think that nickel chromium alloy porcelain teeth are widely used because of their low price. More than 50% of the patients with porcelain teeth choose this kind of porcelain teeth. Biological fusion is good, beautiful, economical and durable. However, some people have confirmed that this kind of porcelain fused to metal teeth has poor biological fusion, which is easy to cause allergy of some people and cause inflammation of skin and mucosa. The specific use of porcelain teeth should be decided after consulting with the attending doctor of the regular hospital.
The choice and use of non precious metal alloys are different in the world. The United States uses more nickel chromium alloys; However, in Europe and Japan, cobalt chromium alloy is basically used for fixation and repair, and it can not be used if the nickel content exceeds 1%. Nickel chromium alloy is easier to cast and more economical than cobalt chromium alloy, but its physical properties and corrosion resistance are not as good as cobalt chromium alloy. When it is exposed to thermal environment, such as porcelain, the physical properties of nickel chromium alloy may change, and the alloy becomes more fragile and is not suitable for long bridges. In this regard, cobalt chromium alloys are much better than nickel chromium alloys in resistance to heat treatment (Morris 1990, sing et al. 1999).
Experts believe that the corrosion resistance in the oral cavity: the corrosion performance of alloys without precious metals is fundamentally different from that of precious metal alloys. Noble metal alloys are mainly composed of noble metals gold, platinum, palladium and or silver. These noble metals have a passivation oxide layer formed spontaneously, so they can prevent corrosion to a great extent. This is also reflected in the release of ions. On the precious metal alloy, the main and secondary components, especially the bonding oxidant and zinc, will dissolve, while the corrosion phenomenon of the alloy without precious metal is determined by its main component cobalt. According to the provisions of the German industrial standard DIN EN iso10271 on corrosion, the ion release of gold alloy is the lowest, followed by titanium, cobalt chromium alloy and nickel chromium alloy.
