A composite is made of plastic and glass the same color as your teeth. It’s used to restore teeth after cavities are removed. They are also sometimes used in cosmetic dentistry to improve your smile’s teeth color and shape.

How does it Work?

The dental assistant usually prepares the composite material, which the dentist places inside the cavity or on the tooth in layers. A UV or other specialized light is then used to set each layer. When this is done, your dentist shapes the tooth to the rest of your teeth. Composites must be polished to ensure durability and avoid staining.

Advantage of Composites

Composites look like real teeth and are much more attractive than traditional fillings. In fact, your dentist can mix shades to get a color that matches the surrounding teeth, while traditional fillings turn black over time as contents oxidize. Composites also bond to your teeth, strengthening the natural structure, a real bonus when significant decay has been removed. Other perks include additional protection against breakage and insulation from temperature changes, especially for food and drinks.

Things to Think About

After your get a composite, the area can be sensitive. Another thing to remember, is drinking tea, coffee and dark wine can change the color of composites over time. If you are concerned about tooth color, ask the dentist to coat the composite in clear plastic to prevent any color change. Composites may wear out faster than silver fillings in larger cavities and hold up better in smaller fillings. Composites are usually less durable and need to be redone more frequently than silver amalgam fillings. They are also more expensive than traditional amalgam fillings. If your insurance doesn’t cover the additional cost, the out-of-pocket cost will be higher. However, that cost may be justified, considering the difference a natural smile can make in your daily life.

Source
http://www.knowyourteeth.com/infobites/abc/article/?abc=f&iid=286&aid=1241
http://www.mouthhealthy.org/en/az-topics/c/composite-fillings