ScienceDaily (Oct. 29, 2012)— Braces made from clear plastic polymer used in dental correction orthodontics have produced very good results in recent years, especially in relation to the improved esthetics when compared to metal braces, but they do present certain problems of wear and tear within the mouth. "We were estimating the friction between teeth and the brackets [braces], and it occurred to us that nanotechnology might be of use to help us resolve this issue," remarked Juan Baselga, head of the UC3M Polymers and Composite Group. The solution that they came up with is to use very hard alumina nanoparticles and spread them evenly in the polysulfone, the polymer mould that Euroortodoncia uses in the industrial production of the braces.
This new process, patented by the company and the UC3M researchers, has produced a new material which increases mechanical as well as friction resistance, thereby maintaining the braces' transparency. "We have been able to develop a more rigid material with this technology which has a clearly improved friction resistance, thus helping to withstand the wear and tear produced by the teeth or by chewing, Professor Baselga explained. In addition, it is biocompatible, which is essential for something that is going to be used in the mouth, and complies with European requirements for products which are in contact with food.
These new types of materials- nano-reinforced plastics- have applications in diverse areas of industry, according to the researchers. In particular, polysulfone is of interest in the bio-health field because of its bio-compatibility in the development of medical- surgical equipment, where it is of the essence to improve rigidity and friction resistance. Furthermore, it has potential applications in the auto industry and in the area of safety such as, for example, the development of a new visor for firefighters.
This innovation allows nanoparticles to be incorporated and evenly dispersed in a polymer mould in a very low proportion. After this process that is based on green chemical techniques is carried out by UC3M researchers, the particles, which are now dispersed in the polymer through micro-extrusion and micro-injection techniques, are then mixed to produce the final piece in the CEOSA-Euroortodoncia . " We measure out the plastic since the minimum that a normal machine can inject is 15 grams, whereas our pieces weigh .06 grams…it would be akin to injecting insulin with a horse syringe," explained the company director, Alberto Cervera. "And with the technology we are using, micro-extrusion and the micro-injection, we are capable of controlling these minuscule quantities of material with the utmost precision," he added.