Replacement of dental amalgams with composite. Why should I do it?

What is a dental amalgam and what is it composed of?

Since ancient times and more exactly since 1819, amalgams have been used in dentistry as a material for the restoration of teeth affected by cavities and some fractures. Restoring “stability and functionality” by “replacing” or filling the spaces produced by lost tissues.

But, what materials does an amalgam consist of? At first glance, amalgam is of a metallic grayish color, because it is composed of an alloy (mixture) of liquid mercury, silver, tin, copper, and a small amount of zinc, among other metallic elements.

However, although they are widely used (even today), their use is highly questioned because they have multiple disadvantages and drawbacks for the patient’s health.

In my particular case, as a knowledgeable dentist, I do not use or recommend the use of amalgams of any kind to my patients. On the contrary, I advise my patients who already have old amalgams to have them replaced as soon as possible. However, it is understandable that some institutions still use amalgams due to their low cost and durability.

I am going to confess that I have received patients in my office who say that other dentists recommended not to replace very large amalgams because of the “risk of removing them”, such as tooth sensitivity or the need for root canal treatment. In my opinion, the risk is not in the replacement, but the professional who performs it. Not just any dentist is qualified to perform the replacement, since this procedure is not only about “replacing the material” but reconstructing the tooth in a safe way. This can only be done by a professional specialized in restorative or biomimetic dentistry.

Disadvantages of the use of amalgams

The use of amalgams has many disadvantages, I will mention the most relevant ones:

• Aesthetically unattractive grayish silver color. It can also produce a phenomenon called “amalgam tattooing” due to the deposition of amalgam residues on the tooth and gum.

• Amalgam is a significant source of mercury exposure, as it can contain up to 570 mg of this heavy metal.
• The patient may develop galvanism or some type of allergic reaction to the components.
• Because this material is so hard, it is incompatible with the mechanics of natural tooth materials, producing “cracks” or microfractures that can compromise the structure and stability of the tooth.

• To prepare the tooth for an amalgam, it is necessary to extract a greater amount of dental tissue compared to a dental filling. Because the retention of the amalgam is mechanical, the amalgam is not really adhered to the tooth and it requires a greater contact surface.

The toxicity of mercury in amalgams

Due to body (oral) temperature, humidity and contact with saliva, amalgams release mercury ions and vapors into the patient’s oral cavity. These vapors are rapidly absorbed by the oral mucosa and are a health hazard.

The greatest release of mercury to the patient occurs at the time of placement of the amalgam and at the time of its removal. For this reason, it has been recommended that dentists and patients use barriers and personal protective elements to avoid exposure to mercury. Among these protective elements we can find mercury filter masks, use of absolute isolation (or rubber dam) on the patients, use of air suction, among others.

Some people with neurodegenerative diseases have tested positive for mercury contamination or poisoning. In addition, there have been cases in which patients with neurological or psychiatric disorders have improved their condition by replacing their amalgams with composite.

There is so much scientific evidence against the use of amalgams that several countries have already banned their use, such as Norway, Sweden, Denmark and others.

Amalgam replacement with composite, how do I do it?

The amalgam is replaced with a material called composite. Composite is a highly esthetic material, which has excellent physical and adhesive properties, allowing to preserve as much of the tooth structure as possible.

I always recommend to my patients to perform the removal of amalgams with absolute isolation, so that the residues do not come into contact with the oral mucosa. It should be taken into account that there are very few of us dentists who know how to do absolute isolation, so probably most dental clinics will not offer it to you.

To begin the procedure, I might ask the patient to take an X-ray to evaluate the extension and state of the amalgam. Afterwards, using the proper personal protection equipments, I proceed to remove the amalgam with the help of a drill. During the removal, I make use of a high suction device to suck the mercury gases produced. Once the amalgam has been removed, I use a Facelight detector with ultraviolet light to verify that there is no hidden cavities. Finally, I perform dental prophylaxis on the patient.

Why does amalgam replacement sometimes fail?

In my opinion, most amalgam to composite replacements are unsuccessful (i.e., dental fillings can be mismatched, can cause decay underneath, can cause sensitivity, etc.) because the practitioner lacks knowledge of advanced restorative dentistry.  In restorative dentistry, materials that emulate internal and external dental tissues are used, in addition to the use of specialized bonding systems, ensuring that the new composite restorations do not fall off, do not leak (cavities) and the tooth is not left with sensitivity.

Considering the above, I always recommend having the replacement done by specialists in the field. In case you wish to safely replace your amalgams, do not hesitate to contact me for a clinical evaluation and to define the treatment plan.