The longevity of a dental filling depends on many factors.
1. the size of the cavity
2. the dental filling material
3. the technique
4. oral hygiene
5. force exertedThe most important predictor of the lifespan of a filling is the degree of tooth structure missing that is being replaced. The larger the filling, the greater the likelihood that a crown will be necessary at some point in the future.
The particular material used to fill the tooth plays a role in the equation as well. Though dental amalgam, or silver fillings, has been used for over 200 years and is still backed by the many dental associations such as the American Dental Association, I have not placed an amalgam filling in my patients on the island. The reason behind is the health risk associated with the mercury it contains and also due to its cracks.
With changes in temperature, mercury tend to expand or contract and cause crack to develop in the teeth. This material is currently banned in many European countries. The larger the filling and the more stress a patient puts on the teeth, the higher incidence of cracked tooth syndrome we see. This syndrome necessitates a crown and at times root canal therapy, and is characterized by biting pain and cold sensitivity.
Applying dental fillings with composite (the tooth-colored filling) is technique sensitive. Composite requires less drilling than amalgam (silver) fillings and is more aesthetically pleasant. It is added in increments in the mouth, and cured, and polished properly to make sure there are no high points or rough ends. Dentistry keeps advancing and hopefully in a near future the life span of white fillings will be increased as well as compressive strength.
Another factor is the hygiene and occlusal force. Bruxism is the term given to teeth grinding. Many patients are unaware of it, because it usually happens during their sleep, however it is very obvious to the dentist. Heavy forces placed on these restorations, mainly in the form of clenching or grinding, may cause the restorations to erode with time.
A mouthguard is a simple preventive, cheap, highly effective and conservative solution to this problem.
If you suffer from this problem, please ask your dentist at your next visit if a night guard is right for you and help extend lifespan of your dental work.