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Dental Materials Reactivity Testing - What You Need To Know

July, 2005
For this month's e-zine, I have a special interview with Walter J. Clifford, known to all as Jess. Jess is founder and head ofClifford Consulting & Research, Inc. which does testing for reactivity of dental materials. As a matter of fact, it was Jess who developed the materials reactivity test. At this point his database includes more than 5,800 products and is constantly being updated. I would venture that Jess is one of the world's top authorities on dental materials. I am proud to know him and to be a friend of many years.

Jess, it is truly an honor to interview you for my e-zine. I am sure that our readers will find this discussion very enlightening. I have used your testing for years, especially in any patient who is in anyway a reactive type of individual.

Some patients are so sensitive that they come in wearing an oxygen mask. Using materials indicated as suitable for that individual, I have not experienced any problems.

Jess, can you discuss the issue of dental materials safety and how materials are traditionally tested?

Traditional thought among dentists suggests that any and every product is safe and effective for any and every patient, especially if it carries a 'Seal of Approval' from some regulatory or professional body. The acceptance and approval process for restorative materials has very little to do with long-term sustained biological safety. Rather, the process focuses on esthetics of the product, its strength and durability when placed in the mouth, its ease of use by the dentist and the relative cost factors when compared to competing products.

A list of judgment criteria for materials evaluation published and taught to dental students by a prominent dental school in the United States features 44 test parameters to determine acceptability. Only two of the 44 parameters relate to safety and biological compatibility. One of the tests determines whether or not the dental material causes cell destruction (cytotoxicity) and the other checks for irritability with direct cell contact in a hamster cheek-pouch. While these two tests are useful in their limited focus, neither examines what will leave the restorative material and enter the body with long term exposure to tissues, body fluids, bacteria and food or beverages.

Chemical constituents resulting from frank corrosion, galvanic currents, off-loading and out-gassing from restoratives are often absorbed and may lead to serious physiological impact and tissue build-up. These, in turn, interfere with normal activity in the cardio-vascular system, the digestive process and gastrointestinal tissue, neurologic function, musculoskeletal strength and coordination and pulmonary efficiency. They can cause real havoc with hormonal functions. Few healthcare professionals would associate dental materials with neurological disorders, skin problems and digestive issues. And we should add that beyond all of these potential problem areas, there is the broad spectrum of "sensitivity" which results from contact between chemicals which exit dental restoratives and the immune system.

Our current materials safety evaluations do not pay much attention to these systemic health problems since they do not occur within the mouth itself. While there is no need for panic, some people will have problems here and there with virtually any restorative product that I could name. Some of these problems will be simple irritations or bad tastes in the mouth. Others will be more serious.

How does your lab test for material compatibility?

We employ broad based immune system screening using antibody detection in the patient's blood serum. The individual antibody record can assist us in knowing what the patient has encountered in the past and has adversely reacted with. When there is a noxious or toxic encounter, the immune system attempts to fight and protect against the offending substance with several mechanisms, including the production of specific antibodies directed against the offending material.

Nearly all adverse reactions to restorative materials result when there is a breakdown or corrosion or off-loading of components from the restoration. These constituents are not peculiar to dental materials. Most adults will have encountered similar components in food, water and various environmental and lifestyle contacts as well as with prior dental placements. For example, if the patient has adversely reacted with nickel from jewelry or stainless cookware, or if adverse reaction has taken place against acrylics found in food packaging or cosmetics or contact in the workplace, then placement of dental materials which contain and can release nickel or acrylics will lead to a similar adverse response in the patient.

We can offer assistance to the dentist and patient by screening the patient's antibody record for specific antibodies which may be present at or above a relevant threshold for the components known to be released by various dental products. Even though many of the adverse encounters began with exposures unrelated to dentistry, the body will react the same when similar offending substances come out of dental restorations. Knowing what reactants are expected to be released from various dental materials and which of these the patient has already had problems with, we can suggest products by trade-name which ought to be avoided in the individual patient and products which could be employed with the least degree of risk.Results such as these are individually tailored for each patient who is tested.

How many products does your lab test for?

Our current dental reactivity testing panel reports positive or negative sensitivity findings on 89 basic chemical groups and families of compounds, and provides simple 'suitable / not well suited' indicators for more than 5,800 dental products by trade-name which are grouped into 30 application categories. We have a substantial number of additional products under study and will be adding these to the database as our evaluations are completed.

Parenthetically, we are preparing to release a new testing panel during Fall 2005 which is based upon the same concepts as the dental panel, but which is oriented to materials used by physicians in orthopedic and implant surgery.

Can you share with us from all of the patients you've tested some observations with respect to materials selection and bioactivity?

With data from more than 41,000 patients, several strong trends have emerged regarding biological suitability and safety of dental materials in the presence of normal body chemistry. 

First, products containing nickel, beryllium, cadmium and mercury fare very poorly across the board. Even when combined with other components, there does not seem to be any reliable mechanism to isolate these metals from causing problems.

Second, noble or precious metal alloys fare much better when they are free of palladium, and to a lesser extent, free of silver. Most of the top level precious metal alloy suppliers have introduced palladium-free formularies as well as those which have little or no silver. This reduces direct exposure to these metals and seems to help reduce the intensity of galvanic cells which may form between dissimilar metal components.

Third, there are some remarkable new advances now available in the traditional porcelain and ceramic crown and bridge products, including feldspathic, leucitic and zircate forms. These materials have great strength and durability while presenting with marvelous esthetic properties. We are seeing successful multi-unit bridge spans which do not require metal frameworks. Best of all, they score quite well in bio-compatibility for a vast number of patients. 

Fourth, there are some truly fine new products coming into the marketplace which blend the qualities of traditional porcelains and ceramics with those of bio-glass ionomers and resin composites. These products often score in the 99 percentile, meaning that 99% or more of patients tested will show 'suitable' with them. They are within the practice scope of most dental offices and permit very pleasing esthetics in the finished treatment.

Finally, the use of lab-formed ceramics, porcelains and hybrid products for crowns, inlays and on-lays which can be milled, placed and adjusted during the same visit to the dental office is revolutionizing treatment protocols in many practices. While not indicated for every case, the fact that these materials are formed and cured outside of the mouth vastly reduces the likelihood of an influx of uncured precursor components to the patient. These materials often score in the 90 percentile or higher.

Next month we will continue our discussion on reactivity testing and delve into the potential problems with different metals in the mouth as well as the possible interactions with implanted materials elsewhere in the body.

Clifford Consulting and Research Inc. (CCR), headquartered in Colorado Springs, Colorado, was founded in 1988 after the invention and development of the Clifford Materials Reactivity Testing (CMRT) concept by Walter J. Clifford, who currently serves as president of CCR. CCR's unrelenting commitment to values such as service, integrity, and innovation in promoting quality care for patients through testing and research has resulted in 17 years of rapid growth as a unique provider in the industry. CCR now offers information, services and seminars to healthcare professionals throughout the United States, as well as international locations.

© 2005, Mark A. Breiner, DDS

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