Our View on Dental Restorative Materials
Modern dentistry gives us the chance to restore most teeth with metal-free dental materials. These include bonded composites as well as all-porcelain inlays, onlays, crowns, and veneers. It is my experience, after muscle testing hundreds of chemically sensitive patients, that most individuals tolerate these classes of materials very well, if adequate precautions are taken during their placement.
At times it is necessary to include some metal in a dental restoration and the choice of metal, in my view, is a crucial one. All too often, too little attention is paid to the quality of metal that is placed in a person’s mouth. As well, little attention is paid to whether different metals are being mixed within someone’s mouth. This often happens when, over the course of many years, a person has a tooth fixed here and another one fixed there without any sense that problems can develop from this kind of mix.
Our mouths are like batteries. Our saliva is a fairly good conductor of electricity and is loaded with charged particles called ‘ions’, which allow current to flow. When two dissimilar metals are placed in an environment rich in free ions, electricity flows due to what is known as ‘the battery effect’. It is usually not enough for most people to feel an electrical shock (although I have had patients where it was), but it is enough to do three potentially uncomfortable or damaging things:
- First, these electric currents accelerate the breakdown of metal restorations. This is a form of electrically induced corrosion that most severely affects the most reactive metals in the mouth. These are typically the silver-mercury amalgams, which, besides containing these two metals, also contain zinc, copper, and tin. Also very reactive are the metals used in non-precious or base metal crowns. These kinds of crowns are less costly than ones that contain precious metals, and without an understanding of the electrical problems that these restorations can be a part of, dentists and their patients often don’t think of the benefits of placing high quality gold containing restorations. The biggest concern of this so-called, “galvanic corrosion” is that it can liberate mercury from dental amalgams.
- Second, these electric currents can alter one’s sense of taste. This may seem like a little problem unless it happens to you! I have had patients who would have gladly had me extract their perfectly good teeth, if only I could rid them of the terrible metal taste that was with them twenty-four hours a day, seven days a week.
- Third, these electric currents can have an effect on the acupuncture meridians that run throughout the mouth and so affect the circulation of the very energies that keep our body in its delicate balance. This can have very strange manifestations, including difficulty concentrating, thinking, altered energy levels or mood instability where this was never a problem prior to having had some dental restorative work.
For these reasons, whenever we use metal, we use the least reactive metals that are available and that will also accomplish our purposes. These most often include dental alloys that contain very high concentrations of gold.
Dental alloys are most often classified into three categories, non-precious, semi-precious, and hi-noble. Even within the category of hi-noble, which must contain a minimum of 50% precious metal, the mixtures of metals and the actual quantity of gold can vary enormously.
In order to provide the least electrically reactive dental restorations possible, we match our dental alloys so that whenever new restorations are placed, there will not be any cross reactivity. The dental alloys that we use all fall within the hi-noble category, but are further distinguished by containing, at minimum, 73% gold. Also, wherever possible, we use a dental alloy that is 99% gold. In this way we absolutely minimize the electrical problems that other alloys can cause. And over the course of time, as we replace old, worn out dentistry we eventually get to a point that all of the metal containing restorations in a mouth are of the exact same composition. When that occurs, there can no longer be any electrical activity to stir up trouble, because once all the metals are identical, the battery effect is no longer possible.