Everything in dentistry has life expectancy. fillings last so long, crowns, root canals last so long an so on. A tooth gets a cavity, the filling that is placed is expected to last 10 to 15 years. That filling wears out and another filling is placed and expected to last 10 to 15 years. When that filling wears out sometimes a root canal and crown are needed which lasts around 15 years.
When that work wears out either another root canal and crown or extraction and implant is needed. In total tooth's life expectancy is around 60 years. There are variables to this such as how big are the fillings, what you eat, how good is your home care and do you have any habits like night grinding or biting your finger nails. The best way to keep your teeth longer is not to get on the cycle in the first place - No Fillings.
Here at Brownstown Family Dentistry we believe in conservative dentistry, that is not replacing fillings just because they are old and only doing necessary dentistry. We believe this and excellent home care will extend the life cycle of the tooth.