Question: What is the future of dental amalgam?
Gerald Denehy, DDS, MS; V. Kim Kutsch, DMD; Richard J. Simonsen, DDS, MS
As a practicing dentist and educator who has placed and taught composite resins for 40 years, I still use amalgam. Amalgam is a workhorse material that has served patients for over 150 years, providing the dentist a vital element in the arsenal to combat dental disease. It is a low-cost restorative material exhibiting excellent longevity in both large and small restorations despite being placed in less than ideal conditions by less than meticulous operators. Unfortunately, it is unesthetic and contains metallic elements that, despite the reassurance of the American Dental Association and improved methods of mercury scavenging, have raised both unsubstantiated health and legitimate environmental concerns. It is often looked upon with distain by dentists with “metal free” practices and has been banned by several countries in Europe. If it is time to sound the death knell for amalgam, one must examine the alternatives.
The alternatives are direct composite resins and indirect restorations. The effect of an amalgam ban necessitating the use of these materials could cost consumers up to $8 billion in increased dental fees the first year and would have a devastating effect on the disadvantaged population, resulting in many untreated patients. Indirect restorations are often less conservative and may be financially unaffordable for a large segment of the population. Direct composite resins are excellent materials capable of tooth conservation. Placement methods and bonding systems have improved dramatically in recent years, resulting in greater ease of placement. Yet, these materials require a disci-pline of technique that is often neglected by some dentists and even impossible in certain situations. Absolute field control, proper light polymerization, and careful attention to placement procedures are essential for long-term success. However, in this era of emphasis on speed and simplification, these elements are often compromised. Amalgam is a material that will properly function under less than optimal conditions with a less than careful technique. Composite resin will not.
This certainly is not to say that every dentist should place amalgams. If, however, amalgam is not part of their armamentarium, then they have the responsibility to practice with the discipline, care, and precision that the alternative materials require. They also should be willing to provide quality, lower-cost restorations for the many economically disadvantaged patients who otherwise will go without treatment.
Although amalgam will continue to be used less and less in the United States, I feel that its banning will not and should not occur in the immediate future. There will be more stringent controls on mercury scavenging systems to protect the environment, and patient informed consent will increase. New generations of dentists will be better trained in the use of alternative materials as dental schools are already devoting more curriculum hours to composite and less to amalgam. However, unless major changes occur that result in the development of a new generation of direct restorative materials, the eventual demise of amalgam will have overall detrimental effects on patient care.
If there is a controversial restorative material, it’s amalgam. But we should first recognize that there is no perfect restorative material. So while amalgam has issues, so does every other restorative material. Amalgam has been widely used and historically has served an excellent role as a long-standing restorative material. Indications today continue to include low-cost services and isolation difficulties during insertion. However, many issues have been raised about amalgam, its use, and disposal. If you look at the current scientific literature, these issues include: removal of healthy tooth structure for retention, undermined cusps and cusp fracture, incompatible coefficient of thermal expansion, post-insertion sensitivity, poor esthetics, and concerns in handling, storage, waste-water, and disposal. The post-insertion sensitivity and cusp fracture can be improved by using resin bases and bonding, but if you go to that point, why not place a bonded esthetic restoration in the first place? Couple these issues with the mercury concerns and the fact that amalgam is being banned in some countries and restricted in others, informed consent is being recommended. That pretty well paints the current landscape for amalgam. The material has strong proponents for its continued use and strong opposition against it, with a great deal of emotion attached to both sides. But the future of amalgam probably won’t be decided on the science as much as esthetics. A 2006 survey of general dentists in the United States revealed that slightly more than half of the dentists no longer use the material at all, and this also represents a strong trend as more dentists continue to stop using it. The main reason is probably related more to esthetic concerns and patient desires than it is the science. So, what’s the future of amalgam? There probably isn’t one, as patients are no longer willing to accept it.
Almost 25 years ago I wrote my first editorial on dental amalgam;1 it was followed in 1991 by two more,2,3 and then in 1995 with one titled, “Move over amalgam—at last.”4 I have been predicting the demise of amalgam, particularly used as a first-time restorative material, for more years than I care to remember.
So, why is dental amalgam still with us, now that we have better materials for just about every situation where amalgam can be used, and after several countries in Europe have essentially banned or at least restricted the material to the point that it is not used? I think we are basically faced with a situation of “old habits die hard.” Younger dentists have been trained in the newer restorative materials, while some older dentists will probably use amalgam until the day they leave the office for the last time.
Change is painful to many, but I would argue that there are several areas where even we in the United States should agree that amalgam should not be used. As I noted in 1995, “Amalgam should never be used as a first-time restorative material. Why? Because better alternatives are available. Amalgam should never be used as a restorative material in pediatric dentistry. Why? Because better alternatives are available.”4
The major benefit of the resin composite and other tooth-colored materials, such as the resin-modified glass-ionomer materials, is that they can be used in far more conservative preparations than can amalgam, thus saving a lot of tooth structure for the patient. This benefit of minimally invasive restorative dentistry is not available to those who continue to use amalgam as a first-time restorative material. I agree with those who say that there is no credible scientific evidence that supports the removal of amalgam for health reasons, except in a small minority of mercury-allergic patients. However, the benefit of conservation of tooth structure makes placement of amalgam as a first-time restorative material, or in pediatric dentistry where bonding and fluoride-release of the restorative material is important, unacceptable in my opinion. Amalgam should never be used in these areas.
The future of dental amalgam is surely bleak. But it will die a much slower death than I thought 25 years ago.
1. Simonsen RJ. Dental amalgam—friend or foe? Quintessence. 1984;15(6): 589.
2. Simonsen RJ. The death of amalgam. Quintessence. 1991: 22(3):173..
3. Simonsen RJ. The amalgam controversy. Quintessence. 1991;22(4):241.
4. Simonsen RJ. Move over amalgam—at last. Quintessence. 1995:26(3): 157.
About the Authors
Gerald Denehy, DDS, MS
Professor and Chairman
Department of Operative Dentistry
University of Iowa College of Dentistry
Iowa City, Iowa
V. Kim Kutsch, DMD
Richard J. Simonsen, DDS, MS
Dean and Professor
College of Dental Medicine