The bonded materials used today are extremely strong and long lasting. There are many different types of bonded materials but their placement is very straight forward. There are a couple of common reasons why new bonded fillings fail. One reason is the temptation to try to push the material to do things beyond its capability. If a filling makes up most of the tooth structure it is much more likely to fail. There are more predictable ways to restore a tooth that is more filling than tooth.
The most common cause of failure of a recently placed restoration is excessive bite trauma. Many times there are signs of bruxism ( tooth grinding ) that a person may be unaware of. An unstable bite that is prone to wear puts tremendous stress on any restoration. Have your dentist analyze your bite or, more simply, look at your teeth in a makeup mirror. If the edges of your teeth are worn or flattened or if you see craze lines in the enamel you may find that your answer was right before your eyes!