Tag Archives: metal dental fillings

Mercury in metal dental fillings

What are metal dental fillings and what do they do to me?

Most metal dental fillings are an amalgam of about 50% mercury and the rest a mixture of mostly silver, with some copper, zinc and tin. Amalgam has been in common use since about 1860. In 1895 the formula was standardised, and about 1970 the formula was changed to give us what I call modern amalgam. The other metal filling material is gold which is alloyed with other metals to improve its handling and durability in the mouth.

It’s obvious that millions of people have had mercury or silver fillings over many generations. No medical problems have been directly linked to their presence in the mouth. So why change if there is no problem? Well nothing is perfect. Amalgam is ugly in the teeth because of the color contrast. It doesn’t support the tooth structure – in fact, it slowly expands over the years and actually leads to cracks in the tooth. These cracks can cause sensitivity, decay and breakage.

What about the mercury? That’s been a concern from the very beginning of its use in the mouth. Nearly all of the mercury stays bound up with the other metals used to form the amalgam. What happens to the small amount that comes out of the filling, and into your mouth? Some is excreted in the urine, some ends up in your hair and fingernails, the rest stays in your body forever. However, the amount that stays in your body is so minute that medical science tells us it would take about 7000 years to harm you. Yes, 7000 years. Some people do claim to be more sensitive to the effects of mercury on their health than others, and this is an open question.

I haven’t used amalgam to fill teeth in over 15 years. Not because I think that it may be a health hazard, but because there are without question better materials available now.

Should I change my metal dental fillings?

Metal dental fillings, also known as dental amalgams, are made of approximately 50 percent silver and 50 percent mercury. You can tell if you have them in your teeth, because they are grey or almost black from corrosion. The corrosion is a natural and harmless result of the silver content.

The major reason to take into consideration when deciding whether or not to change amalgam fillings is the age of the fillings. After about 10 years in the mouth, there are signs of wear and tear. The margins or joints between the metal and tooth starts to crumble at the top where they meet. A ditch or open space develops, which collects food and bacteria and leads to decay creeping down between the tooth and filling. Eventually you have decay under the filling. About three out of four amalgams over 12 years old have this condition to some extent. Another natural tendency of amalgam is to expand over time. The microscopic expansion leads to cracks in the tooth structure appearing.

If your tooth hurts when you bite down on food, it often means that either the tooth or filling has a crack in it.

The most common material used for fillings today is composite resin. This material is tooth colored. Another major advantage of composite is that it can be bonded to the tooth – that is, “glued” to the tooth. This not only results in a very good seal between the tooth and filling, which keeps out leakage, but it also adds support to the walls of the cavity. The support strengthens the tooth which in turn reduces breaking. The opposite of amalgam, which puts expansion pressure on the tooth, leading to cracking and breakage.

If you are concerned, ask your dentist if it is time to replace your amalgam fillings because of age.