A new glass-ceramic material based on magnesium oxide/ alumina/silicon dioxide has been formulated by the researchers of the Otto-Schott-Institut (Germany). Their results, published in late 2011, showed the excellent mechanical properties of this compound. Its translucent white color, obtained with the use of zirconia as an additive, makes it suitable for use as dental material.
Materials for Dental Restorations and Implants
The replacement of lost teeth with implants, or the restoration of natural teeth, are common procedures, which have been performed for many years.
For a material to be employed for these processes, it must have some specific characteristics. The mechanical properties, for instance, are a very important parameter, as these materials undergo high stress during their use.
For this reason, materials used in dental restorations must have enough mechanical strength, hardness, and fracture toughness. Dental materials must also be resistant to scratches and corrosion, and have good durability, as they are normally used for long periods of time, of the order of years.
Dental Restoration Materials: Aesthetics
Further to these properties, the appearance of dental materials is also very important. In fact, restored or implanted teeth should look as similar as possible to the natural ones; this is, therefore, another feature that has to be taken into account, when formulating materials for these applications. Dental restoration materials must be white in color, with a slight translucent shade.
Glass-ceramics in Dental Work
The most common dental materials used today are glass-ceramics. These are glass-based materials, but, unlike glass, they are not completely amorphous but have a certain degree of crystallinity. This is achieved by melting the glass and then re-solidifying it in a controlled way. To better control the crystallization, some additives can be used during this process (nucleation agents).
Currently available glass-ceramic dental materials can be divided into two groups, depending on their value of mechanical strength.In the first group, materials have strength between 100 and 150 MPa, while in the second the range is between 400 and 600 MPa.
- Examples of products belonging to the first group are Dicor® and IPS Empress®; in both cases the main constituent is silicon dioxide (SiO2) glass-ceramic.
As for the second group, an example is IPS Empress® 2, a material based on a lithium disilicate (Li2Si2O5) glass-ceramic.
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