Let’s be Honest about the Materials we are Using
Over the course of my career, I have noticed a profound departure from scientific honesty. Several factors, I believe, have contributed to this disturbing departure—most notably, economics and the increasing influence of corporatism on dental education.
One perfect example is the complete discrediting of the use of amalgam in Dentistry. When I started my career, placing dental amalgam restorations was commonplace. Amalgam restorations have a great track record. I have an amalgam restoration in my mouth that has been there for over 40 years. When I started my career, dentists prided themselves on the ability to provide restorations that had great longevity. I strived to place beautiful amalgam restorations and polish them. I wanted to see them last in health on my patients at hygiene visits.
Suddenly the use of amalgam was criticized because of the “mercury.” It seemed to me that corporate interests wanted dentists to use their composite resin materials and they waged a clandestine disinformation campaign to discredit the use of amalgam. There’s no money in amalgam restorations, but lots of money could be made with all the new materials and their accompanying paraphernalia. The new resin materials were quite esthetic and were a great improvement for anterior teeth. However, they certainly did not exhibit longevity for posterior teeth like amalgam restorations. From a public health standpoint, amalgam restorations help those who cannot afford to place gold restorations infinitely better than resin composite restorations. Resin Composite restorations are not likely to last more than 7 years and are therefore more likely to result in increased problems and expense for patients in the long run.
A great deal of hype was made about mercury escaping from the restorations, but no such mercury is actually measurable. The mercury in amalgam is not free mercury, it becomes part of a compound. The amalgam is not dangerous in this form, and it is not damaging to the environment. (We have been sold a bill of goods with the amalgam separators). A good comparison is to recognize that hydrogen is dangerous in its elemental form but quite harmless as part of a water molecule.
The ADA has consistently maintained that: “Studies continue to support the position that dental amalgam is a safe restorative option for both children and adults. When responding to safety concerns it is important to make the distinction between known and hypothetical risks.” [Monika Rathore, Archana Singh, Vandana A. Pant; “The Dental Amalgam Toxicity Fear: A Myth or Actuality?” Toxicology International; May-Aug 2012; Vol 19; Issue 2.] In 2020, the ADA reaffirmed its position that “dental amalgam is a durable, safe and effective cavity-filling option.” The ADA also supported the FDA’s recommendation “that existing amalgam fillings in good condition should not be removed or replaced unless it is considered medically necessary by a health care professional.” [https://www.ada.org/about/press-releases/2020-archives/the-american-dental-association-reaffirms-its-position-on-dental-amalgam].
Nevertheless, dentists have been successfully intimidated into avoiding the use of amalgam altogether in their dental practices. Since so many patients have read about the dangers of mercury in health publications that dentists simply choose to avoid conversations about mercury with their patients.
It is important to recognize that amalgam has many advantages that resin composite does not. Amalgam can be used where there is moisture and bleeding—such as root surfaces under the gingiva. Composite resin is moisture and technique sensitive and unsuitable for these areas. In these situations amalgam restorations can extend the longevity of teeth. Many dentists brag about being “mercury free.” Is this really fair to patients?
It is an unavoidable fact that ALL materials have plusses and minuses. Certainly, it is important to be aware of mercury so that its use is judicious and minimizes toxicity. The same can be said about composite resin materials, which have demonstrated toxicity as well. Why is there no discussion about the estrogenicity of the bonding resins? Isn’t it only fair that all materials are viewed honestly?
Fortunately, studies conducted by various institutions and by the ADA have shown that while there is estrogenicity of bonding resins that leach into the oral cavity, there are no deleterious effects because of the small quantities released. [Sayed Mostafa Mousavinasah; “Biocompatibility of Composite Resins;” Dental Research Journal; Dec. 2011; Vol 8, Issue 5] Doesn’t this sound like the same case with amalgam?
Now don’t get me wrong. I am not really a huge fan of EITHER amalgam or composite resin. The point of this blog is that honest and fair discussion of ALL materials used in dentistry is needed.
So while we are being honest, it is a FACT that Gold is the best material ever invented for dental restorations. It has the best longevity, workability, biocompatibility and maximum range of indications of any material. Says Helmut Knosp, Richard Holliday and Christopher Corti in their article “Gold in Dentistry: Alloys, Uses and Performance” [Gold Bulletin; Volume 36, Issue 3; p. 93-102]; “It is no co-incidence that in all testing and development of competing materials, gold is always defined as the standard material to be judged against.” But gold has minuses too! It is much more expensive, more difficult to place, and most people desire teeth that are shades of white, not gold.
There is no question that Gold and PFM alloys with precious metals have a track record of longevity. The first restorations were acrylic veneers and I have seen many of them last in the mouth for 50 years and longer. By contrast, the popular all-ceramic restorations do not have a comparable track record for longevity.
All ceramic restorations first appeared on the scene around 1960. The porcelain jackets, as they were called were baked in an oven and had great esthetics. However, a big problem with these restorations is that they were butt-joint restorations and it is a well-known fact that butt-joint restorations can never be sealed at the micron level. As a result, these restorations had a high incidence of recurrent decay. The use of all ceramic restorations was soon confined to anterior teeth in non-susceptible individuals for this reason. This is, in my opinion, the only indication for all ceramic restorations when the best esthetics is desired. By contrast, Gold and PFM crowns, properly designed, are not butt-joint restorations, but extend over the shoulder to grip and seal the root surface. Their design is based the concept of the Mason Jar Cover, the best-known invention for food preservation against bacteria. Porcelain cannot be made in thin sections that extend below the shoulder like these restorations. Posterior PFM restorations fabricated in this fashion have no exposed margins and as a result have esthetics that is more than adequate.
I could not believe the hype that was given to CAD-CAM restorations when they first appeared on the market! I saw immediately that the end product of CAD-CAM is EXACTLY the same as the high fusing porcelain crowns baked in an oven! What is difference does it make how they were made? They are BOTH butt-joint restorations. However, newer dentists were not aware of where dentistry came from. They were easily seduced into buying corporate dentistry’s $100,000 machines. The promise of profit, saving chair time and avoiding laboratory costs was far more enticing than creating restorations that have the best chance for longevity. In addition, newer dentists wanted to be seen as “hi-tech” and in tune with the latest and the greatest. I have been to lectures where the speakers openly bragged about using “high tech” to “sell” dentistry. This tactic creates an illusion that is deceptive and dishonest. It is important to realize that technology is only a tool—not an end in itself. Technology that violates basic principles of health and longevity should always be avoided, no matter how “cool” it appears.
Even worse for Dentistry was the advent of Zirconia—a metal that came from nuclear power plants (and belongs there) that many believe is “all-ceramic.” Zirconia restorations are also butt-joint in nature. There are no standards for Zirconia, and it has never really been tested. Nevertheless, its use has become quite popular because it is inexpensive, and it is white. One major drawback of Zirconia is that it is extremely hard and difficult to work with. Dentistry is not lifetime, and that Zirconia restoration will undoubtedly require replacement at some future date. It will be quite difficult to remove that Zirconia restoration because it is so hard to cut.
Zirconia is not “all-ceramic,” but falls into the realm of “non-precious metals.” [Zirconia is a metal on the periodic table]. But there are other non-precious alloys that are castable. These are also hard materials. Unlike precious metal alloys, non-precious metals do not cast “true.” An alloy that casts “true” fits on the die perfectly immediately upon divestiture. Non-precious alloys often have to be adjusted internally to fit back on the die. There is no comparison with the precision fit of precious metal alloys. Also, porcelain does not bond as well to non-precious alloys as it does to precious metal alloys.
When I gave a presentation at ADA’s Annual Session many years ago, the Annual Session Committee insisted on viewing all of my slides before hand to make sure I was not selling any product or promoting any particular company. Since that time, I have noticed that an increasing number of educational venues want speakers to come with their own financial sponsors to save on honoraria. This is a complete departure from the ADA’s original policy that corporatism was not to infiltrate dental education. In a way, asking speakers to come with corporate sponsors is like “wanting your cake and eating it too.” They want speakers to be unbiased in their educational presentations, but corporate sponsorship comes with a price. Companies want publicity for their products, and they are paying for just that. Can you blame them?
Corporate entities are so much different today than they were at the beginning of my career. In the beginning of my career, they seemed to care deeply about dental education, and they were interested in working with practicing dentists who had evidence for the longevity of their products. I got to know many of the representatives in the laboratory departments of these companies and we had a great deal of mutual respect and sharing of information. Today, it seems that those same corporate entities care only about their bottom line. As long as sales are occurring, they could care less about the opinions of practicing dentists. I have written letters to the current presidents of these companies about various issues. I’m lucky if I ever get a response!
The real issue is that the Dental profession—dental companies, dental laboratories, and dentists–need to have frank and honest discussions about materials and products. We should aspire to high standards and our allegiance must always be first to patients, and not to corporate entities. And we should demand that corporate entities step up to the plate and work honestly with the practicing dentists. We want them to care as much about our patients as we do.