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  • Dr. David Alfaro

That crazy dental amalgam

I am sure that every dentist out there has had a patient present with a main concern of, "my naturopath told me to get rid of my dental amalgam because of the mercury." Or, "I read on this health website that my dental amalgam is going to give me Alzheimer's."

Thank you internet, you make my job harder.

There really is no debate about it. Yes, there is mercury in dental amalgam, and yes, it can enter the bloodstream. Whether or not it is actually causing all of these problems, however, is debatable.

Regardless of one's stance on the health effects of dental amalgam, we have to take a look at the alternatives that people are choosing when removing their metal fillings. Are they any better than the mercury laden restorations of yore?

Let us talk about "white fillings".

What kind of dental fillings are currenty available?

Dental amalgam has a long history in dentistry. It is an alloy that consists of mercury, tin, copper, silver and other metals depending on brand and properties. Amalgam has long been considered the gold standard, and many people still use it today.

This type of material does not actually stick to the tooth, but stays in place because of the cavity preparation design. It is for this simple reason that I do not use amalgam in my office. When we prepare a cavity for an amalgam filling we have to create a hole in the tooth that is wider at the bottom than at the top, so that when the material hardens, it is locked in place. We therefore are creating a big hole in the tooth that is not actually related to where the decay is, but based on the properties of the dental material.

White fillings on the other hand, are designed to stick to the teeth. Composite restorations have not been around very long. Yes, we have been experimenting with gluing plastics to teeth since the 50's, but clinically reliable results were not acheived until the early 80's, and those composites had pretty poor properties and were inferior to the metal version. Today's restorative composites and adhesive systems provide us with a treatment option that is equal to dental amalgam, even though many old timers still swear by the classic metal technique.

Because the composite restorations stick to the tooth, we are no longer forced to cut huge holes in order to complete our work. We just need to remove the decay and then fill it. This allows for a much more conservative approach than what was done in the past. The more we learn about the longevity of restored teeth, the more we see that it is the conservation of tooth structure that is the key to tooth survival.

What is in these composite restorations?

We all know that people are switching to glass and stainless steel water bottles because of the potential negative health effects of plastics. Well I hate to break it to you, but those same "dangerous" plastics are in the fillings that go in your teeth.

There are many older brands that had BPA in them, but since the news broke that BPA may be bad for you, manufacturers have wised up and are marketing BPA free composites. But realistically, if you look at the composition of these plastics, they are all potentially toxic to some effect. There is no getting around it.

Furthermore, the plastic "composite" material does not stick to the tooth by itself; it requires a bonding system. The tooth is ionic, and has a charge, but the plastic does not, so we need an adhesive to make the two materials compatible. There are hundreds of brands of bonding systems, all filled with different solvents and liquid plastics that are key to the adhesion process. We simply cannot glue this type of filling to the teeth with out these chemicals.

Many of these plastics, solvents and resins are toxic to human cells and lab animals in benchtop research, and are harmful if they enter the water systems.

What about natural fillings?

Some of my patients have gone to "holistic" dentists who give them "biocompatible" fillings. There are dentists that make their patients go for bloodwork and allergy testing to make sure that they do not have reactions to the dental materials that are available. When I first encountered this, I was intrigued! Of course I want to find a natural option that is biocompatible and less harmful for the environment! So when I had a patient come along who was really cautious about the materials I was using because she had undergone this testing at a "holistic" dental practice, I called up the office to ask what they use.

The exact same plastic material that I was using already.

There is no such thing as a natural, holistic dental filling material. They are all either metal, or plastic. Yes, there is research going on to pick the least harmful plastics, but plastic is plastic. So please do not fall for this "holistic dentistry" marketing fluff.

And PLEASE do not go on YouTube and try those homemade fillings. Of course you can make a natural paste that firms up to plug a hole in your tooth. But that material dissolves in the oral enviroment and does not properly seal the cavity to the bacteria that cause tooth decay. Even professional, high quality, dental fillings that are properly placed, have limitations in how well they can seal off the cavity, so a flimsy homemade filling simply doesn't work. Did I mention that it is zinc oxide that these hippies are using? Zinc is toxic too by the way......

So what are our options?

As a dentist, I pick composite because it allows me to be conservative in my restorative approach, and I have to accept it for what it is. Yes, I use a BPA free material, but I know that the other plastics can be just as harmful. For larger fillings, I recommend that a patient get gold or bonded porcelain, but.....the cements are still resin based and use the same adhesives, and the cost is much higher.

I absolutely do not recommend the removal of dental amalgam. If the filling is sound, there is no reason to remove it. First of all, we risk stirring things up. I have had patients end up with lingering tooth sensitivity in a previously asymptomatic tooth after a metal filling is cut out, and in a couple of instances to the point where a root canal filling was required. Second, the cutting out of dental amalgam liberates all of the mercury at once. It gets aerosolized and absorbed by the lungs with a very high efficiency, even if it is done under rubber dam isolation with good high volume evacuation. And the final reason is, what we are putting in there better? No. We are replacing mercury for plastic and both have potential negative health effects.

For my patients, the best solution is to not get cavities in the first place. I focus on prevention at my practice, even though I am a specialist in replacing missing oral structures. In fact, it is because I see the complications of dental caries, periodontal disease, and dental work every day, that I constantly harp on my patients to improve their home care.

Most of the disease I deal with in my practice is completely avoidable and is behaviourly acquired. Brush your teeth. Floss. USE FLUORIDE. Damn hippies and their fluoride avoidance. Fluoride is proven to reduce the incidence of tooth decay when used at over the counter concentrations, and those articles that claim that it is neurotoxic and lowers IQ are full of assumptions and unaccounted for variables.

I did not really think that water fluoridation was so important, considering that most people brush with fluoridated toothpaste and visit the dentist.....but I was wrong. Even in an era where people have decent access to fluoridated dental products and professional dental care, the removal of fluoride from drinking water has caused an increase in tooth decay in Calgary. This is modern proof (although it also has its limitations) that fluoride has clinically relevant effects on caries risk reduction.

And the biggest predictor of future tooth decay is a history of tooth decay.

Thanks for reading!

Dr. Dave

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