Search

A discussion of the appearance and diagnosis of this soft tissue discoloration caused by dental silver amalgam is presented.

It is known that macrophages play an important role in the removal of foreign particulate matter from tissue. When powdered dental amalgam is introduced into the soft tissues an amalgam tattoo is formed due to the intracellular degradation of amalgam by macrophages and their polykaryons. It was therefore feasible to study the effects of particulate amalgams as well as their individual phases on macrophages in vitro. The parameters compared were rate of the phagocytosis, changes of cellular morphology, and release of lactate dehydrogenase (LDH) to demonstrate plasma membrane permeability. It was shown that all the alloys except the Sn8Hg particles (gamma 2-phase) and gamma 2-containing Revalloy were effectively phagocytized by macrophages, and the alterations in cellular morphology were slight during the first day. Prominent cellular damage was seen in cultures treated with particulate Ag2Hg3 (gamma 1-phase) and Revalloy for 1 week. A slight increase in LDH activity in the medium was seen one hour after the alloy treatment. The LDH activities due to the amalgam treatment increased in the order Dispersalloy less than Revalloy less than Sybraloy. Intraperitoneal phagocytosis did not cause any morphological changes in macrophages, but the per cent of phagocytosis was diminished.

Amalgam tattoos are common oral lesions. The case presented here involved a 33-year-old woman who had had an amalgam tattoo for 2 years and complained of localized soreness and occasional swelling as well as systemic symptoms of weight loss, fatigue, sinusitis, and headaches. After excisional biopsy of the lesion, the patient's complaints ceased dramatically. It is suggested that alterations in healing due to the presence of amalgam particles led to systemic as well as local disease.

A case of foreign-body reaction to amalgam tattoo in edentulous gingiva is described. Asteroid bodies were found inside giant cells of the reactive tissue. The similarities of these bodies to those seen in other diseases are discussed.

Powdered dental amalgam that had passed through either a 106 microns or a 45 microns sieve was implanted subcutaneously in guinea pigs for periods of up to 2 yr. The renal cortical mercury levels associated with the 106 microns material were on average 16% of those produced by the 45 microns material. A reduction in the amount of 45 microns powder implanted, by a factor of 75%, resulted in a fall of only 27% in renal mercury concentrations. The marked effect of particle size on mercury release may be explained by the large increase in the proportion of implanted material that was degraded within phagocytic cells in the local lesions.

Routine histochemistry, special stains, and energy dispersive x-ray microanalysis (EDX) were used to analyze 15 cases of presumptive amalgam tattoo. Histologically, the fine, spherical, golden brown granules of amalgam were remarkably similar to hemosiderin and melanin granules, and routine and special stains were not always reliable in differentiating one from the others. EDX provided a simple, fast, inexpensive, and reliable method for identifying the precise elemental composition of the pigmented material.

Dental amalgam, either in the form of a solid rod or as a fine powder was implanted subcutaneously into guinea-pigs and the tissue reactions were examined after varying time periods. The solid rods were enclosed by fibrous capsules within which only extremely limited breakdown occurred. This appears to result from electrolytic corrosion of the gamma 2 (SnHg) phase of the rod's surface. Powdered amalgam induced granulomata and most of the particles of amalgam were actively digested by macrophages and giant cells. This resulted in the progressive loss of mercury and tin from the lesion and the formation of minute particles containing silver and sulphur which became widely distributed throughout the lesion, being associated with basal lamina, collagen and elastic tissue and giving rise to the formation of a tattoo. In contrast, some particles of amalgam, too large to be interiorised, were encapsulated by collagen and persisted almost unchanged. Intracellular small amalgam particles and aggregates of fine particles, resulting from their degradation, were seen within lymph node macrophages. It is extremely likely that the sequence of events leadng to the formation of an amalgam tattoo of the oral mucosa in Man are the same.

Amalgam tattooing of the labial gingiva in the maxillary anterior region can be extremely disfiguring to a patient with a high lip line. A case is described in which a palatal gingival autograft was performed.

Soft tissue degradation of the 3 principal amalgam phases have been investigated in relation to their role in the formation of the amalgam tattoo. Each phase, finely powdered, was implanted subcutaneously into the submandibular region of guinea-pigs for periods ranging from 1 week to 1 year. The rates of breakdown were assessed radiographically and the final lesions were examined by light and electron microscopy and X-ray microanalysis. γ 2 (Sn 7 Hg) phase degraded rapidly, mainly extracellularly, and did not produce a tattoo. Both mercury and tin disappeared from the lesion, γ 1 (Ag 2 Hg 3 ) phase degraded less rapidly, both extra and intracellularly, and produced a small tattoo. Mercury was lost from the lesion. γ (Ag 3 Sn) phase degraded slowly, intracellularly, and produced a large tattoo. Tattoos always resulted from persistence of minute particles of silver and sulphur associated with basal lamina and connective tissue.

Twenty-four guinea pigs were subcutaneously implanted with 2 X 25 mg of powdered dental amalgam for between 1 and 24 months. Four animals served as controls. All animals were fed a standard diet containing 0.2 microgram/g selenium (Se). Mercury (Hg) was released from the implants at an average rate of 21.7 micrograms/d and 4.35-16.94 micrograms of Se were consumed daily in the diet. The renal Hg rose to a maximum of 263 micrograms/g at 11 months in implanted animals and 6.65 mg Hg was excreted over 2 yr. The renal proximal tubular cells of implanted animals contained visible Hg deposits in secondary lysosomes and within nuclei containing both Hg and Se. No other signs of obvious renal pathology were seen in implanted animals as compared with controls. It would seem likely that the low Se levels present within this standard laboratory diet were sufficient to protect against Hg toxicity.

The accidental implantation of amalgam into the gingival and even the buccal mucosa is a condition well recognized clinically by dentists, but it may be unfamiliar to dermatologists. Recently we have had occasion to perform biopsies on such lesions, and we were impressed by the histopathologic changes. Search of both the medical and the dental literature failed to reveal a description of the characteristic histopathology, and, therefore, this report is submitted. Silver amalgam is a dental filling material employed throughout the world for the restoration of carious teeth. It is composed of approximately 65% silver, alloyed with 25% tin, 6% copper, and 2% zinc. Bars of this alloy are reduced to a fine powder, washed in dilute hydrochloric acid, and packaged for the use of the practitioner. The dentist mixes this material with mercury, and, while the mixture is in the soft state, he introduces it into the prepared dental

The oral amalgam tattoo is an easily recognizable entity that usually does not require histologic verification, if the investigator is aware of the lesion and its pathogenesis. Seventy-two cases of amalgam tattoo are reviewed.