Lymphocyte levels in subjects with and without amalgam restorations

Article Abstract:

Assertions that dental amalgam (material used for fillings which contains mercury) harms patients' health are evaluated, and the results of a study of one possible health effect are reported. Amalgam opponents have stated that some people are intolerant to mercury and can be poisoned if mercury is present in low levels in the body; they believe that patients should be tested for hypersensitivity. Studies of sensitivity to amalgam have been flawed, and at least one used an agent (mercuric chloride) that provokes an allergic response even at very low doses. A common theme has been the possibility that amalgams compromise patients' immune systems. One study found that the level of T lymphocytes, white blood cells that are the main cell type of the cellular immune system, rose when mercury fillings were replaced with fillings made of other materials, and fell again when amalgam fillings were put in. However, the study failed to report its methods of counting T cells, the results were presented ambiguously, and only two subjects were studied. To learn more concerning this topic, subjects of different ages with (21 patients) and without (16 patients) amalgam restorations were studied. The subjects completed questionnaires about their exposure to mercury (from certain contact lens solutions, hobbies, and seafood consumption); blood was sampled on three occasions separated by at least two weeks and was assayed for its levels of T and B lymphocytes. The results showed no differences in lymphocyte levels between the two groups for any cell type studied. Furthermore, substantial variability was found for an individual's cell counts at different times; this meant that studies using only a few subjects or only one blood sample could confuse normal variability with a significant difference. A discussion is presented of the role of different subtypes of T cells in the immune system. There is no evidence to support claims that dental amalgam adversely affects the immune system. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Lymphocytes, Amalgams

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Dental amalgam and mercury

Article Abstract:

This review presents issues that have been raised concerning the health risks associated with dental amalgam (mixtures of mercury and other metals used for fillings), a controversial subject since amalgams first were developed in the early 1800's. The gold-film mercury detector can be used to estimate the amount of vapor in a patient's mouth; when properly used, estimates of 1.2 micrograms of mercury per day were made for patients with between eight and nine fillings. Other methods of measurement arrived at similar values. People without occupational exposure to mercury take in between 10 and 20 micrograms per day: thus, the amount contributed by dental amalgam is minor. Those against the use of amalgam often argue that some people are allergic to amalgam, However, the proportion of people with such an allergy is very small. An episode of the television show '60 Minutes' caused alarm when patients who were interviewed stated that their health had improved after removal of their amalgam fillings. This may have raised false hope for people suffering from serious illnesses; also, many of the symptoms that allegedly vanished overnight were not even associated with mercury poisoning. Arguments against the viewpoints presented on the show are outlined. One important factor is the power of the placebo effect, which is known to produce genuine physiological reactions in many people. If mercury amalgams are to be replaced by other restorative materials, the safety of these materials must be ascertained. These include composites (resins), glass ionomer cements, gold and gold alloys, and ceramics. All are associated with physiologic effects; these are described. Toxicity always depends on the dose of the material ingested or absorbed, and scientific evidence must be taken into account in assessing the health risks of dental amalgam. (Consumer Summary produced by Reliance Medical Information, Inc.)

History, Composition, Mercury (Metal), Mercury in the body, Dental materials

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Digital enhancement of radiographs: can it improve caries diagnosis?

Article Abstract:

Computer-aided enhancements of dental X-rays may prove helpful to dentists in determining the extent of cavity damage but at the present time may be impractical. Two general dentists and one X-ray specialist evaluated 18 surfaces of 12 extracted teeth for cavity damage first by traditional X-ray and then by a choice of computer-aided enhancements. Researchers compared these evaluations with microscopic tests done on these teeth that determined the precise depth of tooth damage. The X-ray specialist more closely identified the exact extent of tooth damage than did the general dentists, particularly when using the computer-aided technique. The general dentists accurately identified tooth damage between 12 to 16 times out of 18 times when using either technique. Identifying an appropriate combination of computer enhancements for each evaluation proved to be time-consuming.

Diagnosis, Dental caries, Radiography, Medical, Medical radiography

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