Human oral mucosa is subjected to many noxious stimuli. One of these substances, in those who have restorations, is dental amalgam which contains mercury. This paper focuses on the local toxic effects of amalgam and mercury from dental restorations. Components of amalgam may, in rare instances, cause local side effects or allergic reactions referred to as oral lichenoid lesions (OLLs). OLLs to amalgams are recognised as hypersensitivity reactions to low-level mercury exposure. The use of patch testing to identify those susceptible from OLL is explored, and recommendations for removing amalgam fillings, when indicated are outlined. We conclude that evidence does not show that exposure to mercury from amalgam restorations poses a serious health risk in humans, except for an exceedingly small number of hypersensitivity reactions that are discussed.

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Background Recognition and differentiation of early forms of proliferative verrucous leukoplakia (PVL) could be a challenge to both clinicians and pathologists. Objective To report on a retrospective study that was carried out on 51 cases of PVL that were initially diagnosed as frictional keratosis, oral leukoplakia or oral lichen planus. A secondary objective is to report on the outcome of malignant transformation during follow‐up. Methods Records of patients seen at an oral medicine clinic with the final clinical diagnosis of PVL were audited for early clinical and histopathologic features in their biopsy at first presentation, and for subsequent malignant transformation. Results Fifty‐one patients (25 men and 26 women) with a mean age 51 years (men) and 53 years (women) at initial presentation were studied. 28% men and 11.5% women were current smokers. Initial clinical diagnoses were frictional keratoses (n = 4), Leukoplakia (n = 17) and lichen planus (n = 30). Epithelial dysplasia was reported in the initial biopsy in 12 cases and lichen planus/lichenoid features in 22 cases (22/51; 43%). Malignant transformation occurred in 11/51 patients (21.5%). Conclusion Lichen planus or lichenoid lesions could be the initial presentation of many PVL cases that later develop multiple leukoplakic lesions with a final diagnosis of PVL.