Specific classification of metal braces
(1) precious metal braces
braces in prophase (early 20th century), and much is made of precious metals. As a result of the processing function of the precious metal has a good, suitable for crafts processing technology of the time. And have good corrosion resistant ability, but its defect is also significant, such as hardness and other mechanical function is poor, easy deformation, expensive, and so on. Precious metals are mainly used by gold and gold alloy, nickel silver alloy, etc., the first and second generation of the silk bow braces are made of precious metals.
(2) stainless steel braces
along with the development of the metallurgical industry and machinery industry, the stainless steel material used for orthodontic bracket series step by step. Began in the 1940 s, the third generation of the silk bow braces has started to use stainless steel. Especially in the second world war, the stainless steel for its excellent mechanical functions (such as high hardness, low wire slot friction resistance and low price, etc.), agile replace precious metals as the main stream of fixed orthodontic materials. Today, the stainless steel braces is still the most widely fixed orthodontic clinical use of braces. Other, for stainless steel contain must elements of nickel, so people allergic to nickel is not applicable, there appeared materials, approximately 11.1% of women and 2.2% of men have concluded that to nickel allergy.
(3) the pure titanium braces
in order to overcome the nickel composition in the stainless steel braces allergenic, someone use pure titanium braces are put forward. Pure titanium chamfer qualitative light, good biocompatibility, corrosion resistance. Wire slot friction coefficient and stainless steel braces. But as a result of titanium is expensive, and no significant improvement, beautiful and titanium braces is not much use.
(4) magnetic braces
in developed countries, magnetic slot is also used, the braces by Sm containing 30% and 70% of Co magnetic materials, using braces, with its moving in the direction of the magnetic control teeth nearly far.