Ceradyne, Inc. was a company that made advanced ceramics for defense, aerospace, electronics, and industrial uses¹. It received assistance from the NASA Industrial Application Center, University of Southern California (NIAC/USC), a NASA-sponsered center that provided infromation and retreival services to industry clients and offered asssistance in applying the information¹. Ceradyne, Inc. was looking for a material to be used in infrared radomes (a structure that protects radar equipment, but is transparent to radio waves in order to allow them to pass through) that track heat-seeking missiles¹. The material that they found was translucent polycrystalline alumina (TPA)¹. At Ceradyne's request, NIAC/USC conducted an extensive literature and patent search to provide a technology base for Ceradyne production of TPA¹.
In 1986, Unitek Corporation/3M contacted Ceradyne, looking for a transparent material strong enough to be used in orthodontic treatment¹. Ceradyne suggested TPA and the two companies began development and clinical trials¹. Transcend Brackets were introduced in 1987 and production soared to 300,000 pieces a month¹. According to its developers, this has made it the most successful orthodontic product introduction in history¹.
These ceramic invisible braces are still available today². The ceramic brackets are very stong and generally do not stain². The Transcend brand is still produced by 3M Unitek². Ceramic blends in with the teeth and the ligatures (tiny rubber bands) that hold the brackets together are often white or clear (though they can stain)². The ceramic brackets don't need to be changed for adjustments, only the ligatures². Generally they are more expensive than traditional metal brackets². While Invisalign has become more popular, certain cases can be too severe for Invisalign and orthodontists have less control over the Invisalign treatment since they are computer fabricated by Align Technologies². Orthodontists also require special training to be able to use these technologies².