Injurious effects of mercury as used in dentistry

By E.S. Talbot (1883)

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The subject of mercurial poisoning from the use of amalgam fillings in decayed teeth, has given rise to numberless articles, and has been a source of discussion in dental societies since its introduction into this country. Symptoms of mercurial poisoning have manifested themselves in cases where these amalgams have been employed, causing the scientific members of the profession to investigate these fillings, to determine if these symptoms are due to the mercury contained in its composition. Nor is this investigation confined to men of science; the ordinary practitioner is constantly meeting these symptoms, and by careful observation will be able to diagnose these cases when met with. I will mention two cases which have come under my notice. ”... is it not a necessary consequence that amalgam fillings, which, as I have proved, are constantly giving off mercury fumes to be inhaled into the lungs, not a few times daily, but always, without cessation day or night, is it not a necessary consequence that in many sensitive persons such fillings must produce deleterious effects?” January 18, 1878, Mrs. W_____, 29 years of age, had several amalgam fillings inserted by me. At that time, and for the three succeeding years, she was under a physician's treatment for antroversion of the uterus, when she was dismissed by him as cured. During this time she consulted me at intervals in regard to her teeth. For a year past she has complained of trembling at times, coldness, headache, swelling of the limbs, enlargement of the glands, and pain about the jaws, tongue swollen and sore, teeth loose and tender upon pressure, marked salivation, and a metallic taste in the mouth; appetite poor, and bowels irregular; symptoms gradually increasing until six weeks ago when she was completely prostrated, and confined to her bed part of the time. Wishing to obtain the opinion of others, I consulted three able physicians, all of whom pronounced it a case of mercurial poisoning. Four weeks ago I removed all the amalgam fillings at one sitting, and replaced them with gutta percha. A slight improvement was noticeable within a week, and a few of the symptoms disappeared. I have refilled some of the teeth with gold, hand pressure being required on account of the soreness. The metallic taste had disappeared, the tongue is normal in size, and where before she was irritable and nervous, she is now bright and cheerful, and gaining steadily in weight. Miss M_____, a nurse, 40 years old, came to me at the suggestion of her physician, to have her teeth attended to. Soon after her recovery from diphtheric paralysis of the throat, she had a tooth filled with amalgam. She experienced a disagreeable sensation and some pain immediately after the operation. She suffered greatly from the tooth, and had an excessive flow of saliva. Her taste was impaired, and she felt a paralyzed sensation of the muscles upon that side of the mouth. In nine days she had the tooth extracted. The saliva gradually ceased flowing, but at the time of her visit to my office, four weeks after her tooth was extracted, she had not entirely recovered the normal condition of the muscles. Generally, the poisonous effects of amalgam filling do not manifest themselves immediately after the filling is inserted. Years may elapse before the symptoms indicative of mercurial poisoning, which fact but adds to the danger of this sort of stopping for the teeth. The suspicions are not aroused to the real cause of ailments, until the system becomes saturated. Occasionally other causes undermine the system, and place persons in a condition susceptible to its toxic influences. I found the general opinion of writers on this subject to be, on the one hand, that when mercury and alloys formed a chemical union, and the hardening process took place, the mercury could not detach itself from the other metals. On the other hand, that a chemical laboratory must be set up in the mouth, and the mercury converted into some of the toxic compounds, to produce systemic effects. All experiments hitherto, so far as I know, have sought for the results by supposing that the acids of the mouth acted upon the mercury of the amalgam. These experiments were made largely, if not wholly, from a chemical standpoint, and the results in all cases were wholly insufficient to explain the cause of mercurial poisoning. These experiments were conducted out of the mouth with the different acids at all strengths and at all temperatures without finding any traces of mercury with their reagents. Other results could hardly be expected when we consider that nitric acid affects mercury only at 60 degrees Far., sulphuric acid only when heated, and hydrochloric acid has no effect upon it. Knowing that mercury gives off vapors at all temperatures, which are increased by the action of the heat, I commenced a series of experiments to ascertain to what extent this change takes place in amalgam fillings, and if it is possible for the vapor of mercury to be liberated after the chemical change or hardening process has occurred. In conducting these experiments, I prepared the ammonio-nitrate of silver, as that is a delicate reagent, and with it wrote upon white paper. After putting the amalgam to be tested in a bottle, the strip of paper was placed across the mouth of the bottle and the stopper cemented. Should a mercurial vapor arise, the letters on the paper would become black. Leaving the bottle for ten minutes I examined it again, and found the writing in plain black coloring. This is one of the many experiments similarly conducted, the amalgams varying in age from six months to sixteen years, and immersed in both saliva and water, with a water bath attached to keep them at the normal temperature of the body. They were performed in the dark, as the rays of light decompose the ammonio-nitrate of silver. In each instance, the vapor of mercury responded to the test. To make sure that the amalgams caused the chemical test, an empty bottle was subjected to the same tests, with, of course, no results. The rapidity with which the evaporization of mercury takes place depende upon three factors, namely: the temperature, the area of exposed surface, and the amount of discoloration upon the filling, and not upon the quantity of mercury contained in the fillings. The vapor is given off proportionately with the increase in temperature, the heat of the body being greater than the average atmospheric temperature; the vapor which exudes from a filling in the mouth, exceeds that from a like quantity of mercury exposed in the open air. Amalgams are generally inserted where large fillings and difficult operations are required; consequently the amount of exposed surface is great, and yields vapor abundantly. The manufacturers are endeavoring to place upon the market amalgams which will not discolor in the mouth. Do they consider the disasters they are encouraging? The bright surfaces are favorable to vaporization, and Dr. Watt, who has considered this subject thoughtfully, says: "The worst cases of poisoning we have witnessed are those in which the amalgams retain their original bright color". ”Physicians in treating dyspeptics, anaemics and persons suffering from nervous debility, would do well to examine the mouths of patients, and know if artificial teeth on red rubber, or fillings of natural teeth, have in their composition mercury or any of its compounds.” Dr. Bartholow in his work on THERAPEUTICS says: "As used in the mechanical arts by gilders and others, the fumes of mercury cause wasting, ptyalism, necrosis of bones, trembling, impaired intellect, and, in women, abortion". Professor Haines while journeying on the Pacific coast this spring, visited the mercurial mines, and found, in consulting the resident physician, that few of the workmen escaped salivation, and those connected with the distilling process were obliged to protect the lungs by wearing a shield over the mouth and nose. The foreman of the works, while passing a leaking pipe, inhaled the vapor of mercury, and became so impregnated that he was for a time delirious. The doctor was puzzled that some of the miners, in digging the sulphide of mercury, were salivated, and others were not affected. Upon investigation he discovered that the smokers were the men who were affected by the poison; that in rubbing the tobacco in their hands they mixed the particles of the ore with the tobacco, and the heat in burning reduced the ore to pure mercury, which was drawn through the stem into the lungs. They ceased smoking in the mines, and were not affected after. Parish says that long trituration of calomel increases its power to salivate. This is applicable to all preparations of mercury used with an excipient medicinally. The homoeopaths rub up pure mercury with the sugar of milk into different grades, and these are the finest forms in which mercury is prescribed, and yet the severest cases of salivation and constitutional symptoms have been produced by these agents on account of their being so readily taken up by the blood. Is it not a reasonable supposition that, as the poisonous symptoms are produced in proportion with the subdivision of the particles of mercury, that the system will be more seriously affected by the vapor of mercury, which is finer than any mechanical subdivision can be. In order to ascertain the effects of the vapor of mercury, I have employed it in a series of experiments upon plants and animals. I prepared three two-ounce bottles. The first contained ten grains of pure mercury; the second, an amalgam filling three months old; the third was an empty bottle. In each of the bottles I put two roaches, and then covered the mouths of the bottles with gauze. In two days the one in bottle with pure mercury died, the remaining one lived nine days. In bottle containing amalgam filling one roach lived four days, while the other lived eleven days. Those in the empty bottle lived fifteen and sixteen days. The numerous experiments of this sort proved that the roaches in the bottles containing amalgams invariably died before those in the empty bottles. Among experiments upon animals was one upon a guinea pig placed on a gauze platform in a glass jar over pure mercury. He presented all the symptoms of mercurial poisoning. He became emaciated and trembling, the body and limbs were cold. He lingered along for two weeks, and died. It is the opinion of many eminent scientists that mercury inhaled into the lungs produces a more heightened effect than when taken into the stomach. Among this number Professor Stille in his THERAPEUTICS (Vol. II, page 789), says: "Of the several modes by which mercury is made to enter the body, inhalation most speedily produces the specific influence of the medicine, - which theory confirms the belief that the vaporization of mercury from amalgam fillings, occurring as it does constantly, and being carried into the lungs without cessation, is a most effective manner of producing mercurial poisoning. All persons are not equally affected by the vapor of mercury; while possible for some to inhale mercury without deleterious effects, others would express the most decided symptoms of mercurial poisoning with less quantity. Colson states that in 1821-23 he, with several other interns and externs of the venereal wards of the Hospital de la Petite were salivated by the mercurial atmosphere, nor did they get rid of the affection while they continued to frequent these wards. Résumé First. - Mercurial vapor is given off from amalgam fillings at all ages and from all varieties. Even from fillings sixteen years old the vaporization is sufficient in quantity to respond to chemical tests. Second. - Minute doses of mercury, if taken internally three times a day, are capable of producing decided effect. Third. - Mercury, when inhaled into the lungs, is far more active than when taken into the stomach. Fourth. - If small doses, taken into the stomach occasionally, are capable of producing marked effect, and the vapor is much more active than the solid preparation of the metal, is it not a necessary consequence that amalgam fillings, which, as I have proved, are constantly giving off mercury fumes to be inhaled into the lungs, not a few times daily, but always, without cessation day or night, is it not a necessary consequence that in many sensitive persons such fillings must produce deleterious effects? Fifth. - When tons of this material are consumed annually, is it not credible that many constitutions are affected? Sixth. - Physicians in treating dyspeptics, anaemics and persons suffering from nervous debility, would do well to examine the mouths of patients, and know if artificial teeth on red rubber, or fillings of natural teeth, have in their composition mercury or any of its compounds. Note: The full citation reads: Talbot E.S., "Injurious effects of mercury as used in dentistry", Missouri Dent. J., 15:124-30, 1883.