Composite filling is a tooth-colored plastic and glass mixture used to fill cavities or reshape broken or decayed teeth. This procedure provides good durability and resistance to cracks in smaller to mid-size fillings that need to withstand moderate pressure from chewing. They can be used on either front or back teeth. Beyond cavities, composite fillings are used for cosmetic improvements by changing the color or shape of teeth. Watch how anterior and posterior composite fillings are done and how they might help improve your smile.