Is there such a thing as permanent fillings?
Nothing lasts forever. Most dental materials were not designed to serve as long as we now expect to live. Some materials may last many years, and others, considerably less. The better the original dental material and the skills of the operator, the longer the restoration will last. Lab-processed “indirect” materials will generally last longer than direct placement materials. There is really no such thing as a permanent filling. Everything has a life expectancy, even dental filling materials. Every dental material appears to have two different types of life spans – a functional life span (the length of time a material will last before it fails to function properly), and an esthetic life span (the material, while possibly still able to function, has begun to degrade).
The functional life span failure will either:
- weaken the tooth and/or
- permit decay or gum disease to begin
For example, when a piece of the filling breaks off (often in the case of an amalgam “silver” filling, it causes a piece of the tooth to break off) the tooth requires a new filling.
The esthetic life span failure in fillings can be due to:
- Color change of the filling material
- Color change of the tooth
- Shape of the filling has changed
Luckily, it is a very slow process.
The esthetic life span failure of lab-processed restorations (crowns and bridges) can be due to:
- age and changes in your mouth making the surrounding soft tissues look less acceptable than it was when first placed.
- notches in fillings or under crowns caused by improper brushing or decay
- recession of the gum tissue that exposes darker root surfaces
- porcelain crowns that no longer match the adjacent teeth
- metal margins of crowns that are visible due to gum recession
As a general rule, the more expensive the restoration or dental material, the longer it will last. If you want a restoration that will last the longest time, you will probably need a laboratory “indirect” processed 3/4 or full crown. Direct filling materials are not expected to last as long. The longevity of these fillings will depend on the type of material, the location of the tooth, and the size of the preparation in the tooth. There are also outside considerations such as the skills and knowledge of the dentist at the time, the kind of food you eat, your oral self-care habits, and the structural abuse you place on your teeth. Habits such as clenching and grinding your teeth and chewing hard candies, ice, etc. will tend to quickly degrade the filling material, as well as your teeth, much faster.
Even the best-placed fillings get old. Cement dissolves, porcelain breaks, metals fatigue, resins degrade, and so on. Eventually, pieces of filling material or tooth can fracture or chip. A new cavity may start on an unfilled surface of the same tooth. The filling needs replacement.
Silver amalgam fillings (the black or gray fillings most of us have) can absorb moisture from saliva, expand, and cause the tooth to break. The filling expansion can cause both the filling and the margin between the tooth and filling to become rough. This can promote plaque retention and the start of new decay. When this happens, it is best to replace the filling as soon as possible with a bonded resin, which will require less drilling.
The better the material, the less drastic the thermocycling (hot coffee/cold ice cream and any temperature variations), and the less abusive your personal habits, the longer the filling will last. If you have any of these filling problems, you should have them corrected as soon as possible. Waiting can cause increased severity, and more extensive and expensive treatment may be required, or the problem may become impossible to fix.