Dear Dr. D.,
Do Fillings Cause Cracks in my Teeth?
Silver fillings are still placed by dentists because they are cheaper and faster. If placed properly, they can last a long time, but nothing will stop them from being ugly.
The silver fillings are 50% mercury, and a lot of people are worried about the poisonous effects, but the jury is still out about whether or not mercury locked in a solid-state is harmful. However, the physical properties of mercury are not in doubt.
The old-time thermometers were made with a mercury insert because mercury responded quickly to temperature changes. Even one degree of increased heat would make the mercury swell and “rise” in the thermometer. The cold would make the mercury shrink in size and “fall” in the thermometer.
Enamel which is the outer layer of tooth structure, is basically a crystal and does not react to temperature changes at all. So let’s put the two together.
The larger the filling is, the more it will expand outward. If there is plenty of enamel (usually 2/3 of the width of the tooth), then the expansion is upward. Outward means cracks and new restorations if they’re caught in time. If they’re not caught early, the cracks will turn into fractures and loss of that tooth.