Dentures need to be able to stand the same pressure as natural teeth. At the same time they must be made of a material that makes them look natural. Many dentures might feel right but don’t look natural or the other way around. Now, however, a group of scientists have managed to produce a new kind of glass ceramic with a nanocrystalline structure, which seems to be well suited for use in dentures and bridges due to their high strength and natural shine.
The new glass-ceramics are made on the basis of magnesium-, aluminium-, and silicon oxide and are distinguished by their enormous strength. “We achieve a strength five times higher than with comparable denture ceramics available today”, Prof. Rüssel explains. So far the high density ceramics,have only been used in other fields such as in computer hard drives.
Materials used in dentures are not supposed to look different from natural teeth. It is also important that the colour shade is right, and since the enamel of natural teeth is partly translucent, so should the enamel of the dentures be.
The making of nanocrystals
To achieve this goal, the basic materials of the glass-ceramics are first melted at about 1.500 °C, then cooled down and finely cut up. They are then melted again and cooled down again. Finally, nanocrystals are generated at a controlled heating to 1,000 °C. This way the crystallisation which is so important for the strength of denture material is secured. For the crystals to look naturally translucent, the size of them should not be more than 100 nanometers. This way, they are too small to strongly disperse light and will not look opaque like some other denture materials. The enamel will look translucent and dentures made from this material will be strong and at the same time look natural.
The science of making these nanocrystals will need to be further developed before they can be used in dentures, but researchers feel sure that their technology might be the future of natural looking dentures.
Dittmer M, Rüssel C.: Colorless and high strength MgO/Al2O3/SiO2 glass-ceramic dental material using zirconia as nucleating agent. J Biomed Mater Res B Appl Biomater. 2011 Nov 21. doi: 10.1002/jbm.b.31972