Composite materials, commonly known as “white fillings,” are one type of dental material that is quickly gaining popularity. These are a type of glass-plastic material, often selected for aesthetic reasons because they can be made to look just like a real tooth.
Many patients prefer composite fillings because they are sensitive to the other types of fillings available. Perhaps the most common misunderstanding about composite fillings is that they are all the same. Actually there is a wide variety of component chemicals that can be used to make composites, allowing a dentist to use precisely the right material for any situation.
The plastic portion of the composite is a polymer, a large molecule that is made up of many smaller molecules called monomers. These monomers are usually a type of dimethylacrylate that is able to form long chains, as well as links between chains to form a very stable polymer matrix, like a spider’s web, that will not dissolve in water. Inside the polymer matrix is some sort of glass filler material. Quartz, borosilicate, silicon dioxide, and barium glass are among the more commonly used materials for this purpose. These fillers keep the composite from expanding or shrinking, prevent water absorption, and make the plastic stronger. Some composites also contain catalysts and accelerators to make the plastic portion set more quickly and effectively. Methacrylic acid and colloidal silica can also be added to the mixture to obtain a faster setting and stronger filling. Finally, a surface treatment is used to link the polymer and the filler together. Since there are many different options for each component, and not every component is used, there are literally thousands of possible combinations of chemicals that can make a composite material.