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In dentistry, a variety of potentially allergenic metals are used, such as mercury, palladium, nickel, gold, chromium, cobalt and other metals. This paper describes a diagnostic approach from a dentist’s point of view, which enables analysis of metals in a patient’s oral cavity. If metal allergy is suspected, a micro analysis can be used to determine which metals are present in the restorations. When the exact composition of the dental materials is known, the patient can be tested in vivo (patch test) and/or in vitro (lymphocyte proliferation test) to reveal sensitization. Two patients with nickel allergy are described where removal of nickel-containing materials (bridge and orthodontic wire) resulted in the marked alleviation of symptoms and improvement of health. Finally, if allergy to specific metals has been established, the restorations containing the implicated metals should be removed to discontinue the exposure and thus facilitate the patient’s health.

OBJECTIVES:
This study was carried out to investigate the potential of titanium to induce hypersensitivity in patients chronically exposed to titanium-based dental or endoprosthetic implants.

METHODS:
Fifty-six patients who had developed clinical symptoms after receiving titanium-based implants were tested in the optimized lymphocyte transformation test MELISA against 10 metals including titanium. Out of 56 patients, 54 were patch-tested with titanium as well as with other metals. The implants were removed in 54 patients (2 declined explantation), and 15 patients were retested in MELISA.

RESULTS:
Of the 56 patients tested in MELISA, 21 (37.5%) were positive, 16 (28.6%) ambiguous, and 19 (33.9%) negative to titanium. In the latter group, 11 (57.9%) showed lymphocyte reactivity to other metals, including nickel. All 54 patch-tested patients were negative to titanium. Following removal of the implants, all 54 patients showed remarkable clinical improvement. In the 15 retested patients, this clinical improvement correlated with normalization in MELISA reactivity.

CONCLUSION:
These data clearly demonstrate that titanium can induce clinically-relevant hypersensitivity in a subgroup of patients chronically exposed via dental or endoprosthetic implants.

OBJECTIVES:

Chronic low-level metal exposure may result in metal sensitization and undesirable side-effects. The main sources of metal exposure are from the environment or from corrosion of dental metal alloys. Affected patients are routinely diagnosed with the epicutaneous (patch) test. However, such testing may induce false-positive (irritative) reactions and may in itself sensitize or exacerbate symptoms. Alternatively, MELISA (Memory Lymphocyte ImmunoStimulation Assay), an optimized lymphocyte transformation test (LTT), can be used. In this study we analyzed the overall frequency and distribution of metal sensitization among symptomatic, metal-exposed patients. In addition, we determined the reproducibility of the assay and assessed its clinical relevance for detecting and monitoring hypersensitivity to metals.

METHODS:

To analyze the frequency and distribution of metal sensitization, blood from 700 consecutive patients was tested against a total of 26 metals in the validated LTT-MELISA. For reproducibility testing, 391 single metal tests from 63 patients were performed in parallel. Finally, to assess clinical relevance, 14 patients with known metal exposure showing local (dry mouth, Oral Lichen Planus, Burning Mouth Syndrome, eczema) and/or systemic (chronic infections, fatigue, autoimmune disorders, central nervous system disturbances, depression) effects were tested in LTT-MELISA. In 7 cases testing was repeated following removal of the allergy-causing metals or, in 2 additional cases, without therapeutic intervention.

RESULTS:

Of the 700 patients tested, 74.6% responded to >/= 1 metal in LTT-MELISA, with a subgroup of 17.9% responding to >/= 3 metals. Reactivity was most frequent to nickel (68.2%), followed by cadmium (23.7%), gold (17.8%), palladium (12.7%), inorganic mercury (11.4%), molybdenum (10.8%), beryllium (9.7%), titanium dioxide (4.2%), lead (3.7%), and platinum (3.4%). Reproducibility was 94.9%, with most discordant results in a low-positive range. Removal of the alloys or prostheses containing allergenic metals resulted in remarkable clinical improvement correlating with a significant reduction or complete normalization of specific lymphocyte reactivity. In contrast, both LTT-MELISA reactivity and clinical symptoms remained unchanged in follow-up samples from the 2 patients who did not remove the source of metal exposure.

CONCLUSION:

The optimized LTT-MELISA test is a clinically useful and reliable tool for identifying and monitoring metal sensitization in symptomatic metal-exposed individuals.