Dental Fillings and Dental Amalgam: A Complete Guide

The term “dental filling” is gradually disappearing in favor of the term “dental amalgam” which is used systematically by dentists. It is in fact the same thing and should not be confused with resin composite. We will therefore use both terms interchangeably in this article.

What is the purpose of dental fillings/amalgams?

Dental fillings are used to fill teeth when they have been damaged by cavities. Dental amalgam is widely used because of its low cost and excellent resistance over time. It is used to treat the teeth at the back of the mouth (molars and premolars). For visible teeth (incisors and canines), composite resin is preferred.

The composite resin

The composite resin has the same function as the filling, but its composition and especially its color are different. It is made from plastic and glass compounds and matches the color of the natural tooth.

Composite resin is more expensive, but is preferred for its aesthetic aspect. It is also called “white filling”. So far, it is less resistant to pressure and wear, but technological advances will one day allow it to compete with gray fillings.

What is the composition of the dental filling/amalgam?

The name “dental filling” has fallen into disuse because it is confusing, as “fillings” do not contain lead. Fortunately, it is necessary to specify, because lead is harmful to our organism.

It is a metallic colored amalgam that is composed of 50% mercury and the other 50 percent is divided between different powders of silver, tin, copper and zinc alloys.

This mixture is kneaded until a paste is obtained that will fill the cavity created by the decay – after being cleaned and sterilized by the dentist – and will harden so that the tooth regains its original shape and does not interfere with occlusion and mastication.

This material has the particularity of adhering perfectly to the original tooth and becoming as resistant as the natural dental tissue.

How long does a dental filling last?

The technique of dental filling has existed for over 150 years and of course, techniques have evolved and materials have been perfected.

Over time, the filling changes in volume. The larger the filling, the worse this change will be for the tooth. If it shrinks, it leaves space for bacteria – and thus a new cavity – and if it grows, it risks fracturing the original tooth.

This is why it is recommended for small fillings only. In this case, it can be kept for more than fifteen years.

Except in the case where your filling “pops out”, your dentist will check during each routine annual visit whether or not you need to change one or more of your amalgams.

The mercury controversy

Mercury, ingested in significant doses, is harmful to our body. There is a controversy on this subject between researchers who believe that the dose in a filling is minimal and therefore presents no risk, and others who are more alarmist and believe that even an infinitesimal dose is deleterious.

How does mercury get into our bodies?

The mercury present in the filling is subjected to the shocks of chewing, which releases a tiny quantity that is then ingested, along with the food. However, it is not assimilated by the body, but evacuated with the stools.

An even smaller part is inhaled as a vapor that is naturally released in the mouth. It is assimilated by the blood and the lungs, before being rejected in the urine.

If you look at a filling after fifteen years, it will not show any wear to the naked eye, which is a good indication that the amount of mercury that has been released from it is really tiny.

The people most exposed to mercury are dentists and no occupational disease has ever been detected in this regard. So there is no need to be overly concerned. Moreover, fillings are less and less used in favor of composite resin which contains no mercury or any other metal.

Allergy cases

Cases of allergy to amalgam are quite rare. They affect less than 3% of the population.

Unfortunately, because of the pollution of the planet, you find mercury in nature in much larger quantities. The waters are the most affected, rivers and oceans, and therefore the fish we eat are often contaminated.

Are there any contraindications to dental fillings?

Your dentist needs to know your medical history and conditions. He is the first to advise you on the type of filling you will need.

People who are allergic to mercury, but also to other metals contained in amalgams, should turn to resin composites.

Fillings are also not recommended for people with kidney failure or immune deficiency.

If you have many fillings, peroxide bleaching should be avoided, as the chemical reaction releases some mercury vapors. You can, however, spread the whitening gel so that it treats only your visible teeth – incisors and canines – which do not normally have mercury fillings.

Changing fillings also releases some mercury particles, but these remain in minimal amounts.

Two Scandinavian countries – Norway and Denmark – have already banned the use of mercury in all areas, including dentistry. In any case, given the advances in resin composites, the use of gray fillings will gradually disappear.

Fillings for pregnant women

There are no contraindications for a pregnant woman to have dental work done. X-rays are not harmful either, you just need to tell your dentist about your condition, he will make you wear a lead gown. In any case, the rays of the radio are really focused on your mouth and are not likely to reach the fetus.

Pregnant women who experience nausea and vomiting are more likely to develop cavities because the acidity attacks the enamel. Those who tend to snack too much between meals without brushing their teeth are also at risk of developing cavities.

These cavities must be treated because the bacteria that grow in the cavity infect the saliva you swallow and pass into your body, including your baby.

However, it is better to avoid gray fillings, and prefer white resin fillings. This is also true during breastfeeding. In any case, you should not let the decay grow and risk a more serious infection that will be much more harmful than tiny mercury particles.

The cost of fillings

The cost of a filling differs according to its size, its location in the mouth, the age of the patient, the dentist…

An amalgam costs between 15 and 35 €.

The procedures to treat cavities are reimbursed up to 70% by the Health Insurance, following the conventional tariff.

• Treatment of a cavity on one side: 19.28 € so reimbursement of 13.50 €.
• Treatment of a cavity on both sides: 33.74 €, so reimbursement of 23.62 €.
• Treatment of a cavity with three or more sides: 40.97 €, so reimbursement of 28.67 €.

Ask your complementary health insurance company which can reimburse you for the rest of the cost, in part or in full.

What future for dental fillings?

Dental fillings as they exist today – gray and metal-based, including mercury – should gradually disappear in favor of resin composite.

It is still widely used for small cavities in the back of the mouth, but technological advances will eventually make resin just as competitive. For now, it suffers from being even more expensive, but also from being less sustainable. For comparison, it costs between 30 and 120 € and lasts less than 10 years.

Resin adheres less well to tooth tissue and is less resistant to abrasion. The disadvantage of changing a filling, besides the new expense, is that the dentist will dig the tooth a little deeper each time to adjust the repair.

The great advantage of resin is its aesthetic adaptation. Its color can be adjusted to the natural color of your original tooth. It is then perfectly invisible and, even on the incisors, no one can suspect that you have had a decayed tooth. Your smile is perfect!

To this day, fillings or amalgams are the best solution for treating small cavities in the back of the mouth.

They will gradually be replaced by other materials, but in the meantime, it is much less risky to have a little mercury – or other metals that are part of the alloy – than to let cavities spread and cause much more serious infections.