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Oral pigmentation may be exogenous caused by deposition or introduction of some material in the oral mucosa or endogenous due to increased melanin production or the number of melanocytes. A white female patient, 33 years old, with a black stain located in the gingiva between teeth 34 and 35, approximately 5 mm in diameter, asymptomatic, with 4 months of evolution, was attended to in oral medicine. A periapical radiography was performed, which did not present alterations. The probable clinical diagnoses were an oral melanotic macule, amalgam tattoo, and oral nevi. After excisional biopsy, microscopic analysis revealed the presence of increased melanin pigmentation along the basal epithelial layer and metal fragments within the connective tissue. These characteristics confirm the rare diagnosis of mixed injury of oral melanotic macule and amalgam tattoo. After 6 months the patient did not present with a recurrence of the lesion and is in good health.

We report an unusual case of a 1.5-cm dark macule on the edentulous posterior mandibular alveolar ridge. The lesion affected a 62-year-old woman referred by a clinician to the oral medicine service with suspect of melanoma. Clinical investigation found no signs of pain and discomfort. The patient stated she had not noticed the lesion previously. An excisional biopsy was performed and during the excision a loose brownish granular material within the submucosa and over the mandibular bone surface was seen. This material was curetted and submitted for microscopic evaluation. The histopathologic report described a loosely organized connective tissue with blackened granular agglomerates that also stained the elastic collagen fibers dispersed in the matrix and in the vessel wall leading to a foreign body–type granuloma with focal argyrosis (amalgam tattoo). Postsurgical follow-up of 11 months was uneventful.

Amalgam tattoo, the most common exogenous oral pigmentation, can sometimes be confused with melanotic lesions, being then biopsied. We present the clinicopathological characteristics of 6 biopsied cases (5 females and 1 male) of oral amalgam pigmentation. The most common location was the gingival mucosa, followed by the buccal and palatal mucosa. Morphology and distribution (stromal, perivascular, perineural, endomysial) of pigmentation was variable; there was only 1 case with fibrous capsular reaction and likewise only a single case of granulomatous foreign body reaction. Morphological variability is conditioned by the timing and amount of the pigment deposit, which is often associated with infiltration by mast cells (CD117+), as well as overexpression of metallothionein and HLA-DR at different tissue levels.

Amalgam tattoos occur when small particles of dental amalgam, composed largely of silver (Ag) and mercury (Hg), are inadvertently implanted into oral soft tissues during dental procedures. Metallothioneins (MTs) are ubiquitous, low molecular weight, cysteine-rich, metal-binding proteins that are inducible by many agents including metals and may be involved in the detoxification of toxic metals such as Hg. In this study, the correlation between MT expression and amalgam tattoos in human gingiva was investigated using energy-dispersive X-ray microanalysis (EDX) and immunohistochemical techniques. Light microscopically, amalgam tattoos presented as either fine granular particles or larger discrete opaque globular particles in connective tissues. EDX revealed the smaller particles to be silver sulphide (Ag(2)S), while the larger particles exhibited a shell of Ag(2)S that contained irregularly distributed masses of Ag and Hg. Particles of tin (Sn) were also found. No MT staining was observed in collagen, fibroblasts or blood vessels in areas exhibiting abundant amounts of embedded fine granular Ag(2)S particles. Blood vessels exhibiting relatively few amalgam particles stained positively for MT. Cells with the morphological features of histiocytes located directly adjacent to larger pieces of amalgam showed intense MT staining. These results indicate that amalgam tattoos contain no Hg or free Ag except in large globular pieces of amalgam, which still contain Hg and which induce MT expression in adjacent histiocytes. This suggests that Hg leaching from impacted dental amalgam particles induces MT, while residual Ag(2)S and Sn particles do not. MT may therefore act to reduce Hg exposure in patients with amalgam tattoos.

Energy dispersive X-ray microanalysis is a powerful tool that can reveal the presence and relative quantities of elements in minute particles in biologic materials. Although this technique has been used in some aspects of dental research, it has rarely been applied to diagnostic oral pathology. The purpose of this paper is to inform practicing dentists and oral specialists about the diagnostic potential of this procedure by presenting three case reports. The first case involved the identification of flakes of a metallic material claimed by a 14-year-old girl to appear periodically between her mandibular molars. In the second case, a periodontist was spared a lawsuit when a freely mobile mass in the antrum of his patient was found to be a calcium-phosphorus compound not related to the periodontal packing that had been used. The third case involved the differential diagnosis of amalgam tattoo and graphite tattoo in a pigmented lesion of the hard palate mucosa. The results of the analyses were significant and indicate a role for this technique in the assessment of selected cases. Potential for wider use of energy dispersive X-ray microanalysis in diagnostic oral pathology exists as research progresses.

A series of 268 cases of amalgam tattoo is analyzed both clinically and histologically. The most common location was the gingiva and alveolar mucosa, followed by the buccal mucosa. Histologically, the amalgam was present in the tissues as discrete, fine, dark granules and as irregular solid fragments. The dark granules were arranged mainly along collagen bundles and around blood vessels. They were also associated with the walls of blood vessels, nerve sheaths, elastic fibers, basement membranes of mucosal epithelium, striated muscle fibers, and acini of minor salivary glands. Dark granules were also present intracellularly within macrophages, multinucleated giant cells, endothelial cells, and fibroblasts. Although in 45% of the cases there was no tissue reaction to the amalgam, in 17% there was a macrophagic reaction and in 38% there was a chronic inflammatory response, usually in the form of a foreign body granuloma, with multinucleated giant cells of the foreign body and Langhans types. Asteroid bodies were also found in some of the foreign body giant cells.

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

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.