The dental composite resin is a synthetic material commonly used to aesthetically repair cavities in front teeth or on visible parts of teeth. Composite is also known as a white filling and is widely used because its color can be closely matched to existing teeth. However, over time, the same process that caused you to need a filling can affect the restoration. For instance, more tooth decay and open spaces around the edges of the filling allow bacteria to seep in. In addition, trauma from an injury or biting on something hard can cause the filling or the tooth to crack. The larger the composite filling, the more likely you are to have a fracture or cracked tooth. Even small cracks can allow bacteria into the tooth causing decay or infection leading to further destruction. A cracked tooth may or may not be sensitive to hot and cold or be painful when biting or chewing. Regardless, once the restoration is compromised, the tooth structure will be compromised and cracks. That progress too far can result in entire sections of the tooth breaking off, and in some cases, loss of the tooth entirely. It is important to consult with your doctor on the best course of action to repair a tooth craft from a large composite filling.