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Mercury (Hg) is widely used in the dental working environment, exposing dental practitioners and assistants to potentially toxic Hg vapors. Concentrations of Hg in vapor and in particulate matter (PM10) were measured in the Dental Simulation Laboratory (DSL) and in the Dental Clinic (DC) at the School of Dentistry, University of Puerto Rico. PM10 samples were collected over a 36-h period and Hg vapor was collected for eight-hour periods. PM10 mass was determined gravimetically and Hg (bound to PM10 and vapor) was extracted and analyzed by atomic absorption. Indoor levels of PM10 in the DSL ranged from 9.2 to 41.6 microg/m3 and 35.0 to 68.2 microg/m3 in the DC. Levels of particle-bound Hg ranged from 0.1 to 1.2 microg/m3 and in vapor 1.1 to 3.3mg/m3 at the DSL; the DC levels ranged from <0.01 to 0.2 microg/m3 for particle bound Hg and 13.6 to 102.7 microg/m3 in vapor. PM10 concentrations were below Indoor Air Quality suggested limits for total dust (100 microg/m3). Levels of mercury bound to PM10 were low; however, mercury vapor was several times higher than the suggested OSHA (permissible exposure limit–100 microg/m3) in the DSL.

Apical periodontitis is produced in the majority of cases by intraradicular infection. Treatment consists in the elimination of the infectious agents by endodontia. Even when carrying out a correct cleansing and filling of canals, it is possible that periapical periodontitis will persist in the form of an asymptomatic radiolucency, giving rise to the post-endodontic periapical lesion.

The clinical manifestations of contact allergic dermatitis to dental materials are not uniform. This study was performed to detect the frequent allergens in the dental series associated with contact dermatitis and to define the causal relationship between the different allergens and the relevant clinical presentations. Between the years 2000 and 2004, 134 patients, aged 20-80 years, were patch tested. 121 patients were included in the study. The most frequent oral manifestations were cheilitis and perioral dermatitis (25.6%), burning mouth (15.7%), lichenoid reaction (14.0%), and orofacial granulomatosis (10.7%). 18 (14.9%) patients were dental personnel, all of whom suffered from hand dermatitis. The common allergens detected included goldsodiumthiosulphate (14.0%), nickel sulfate (13.2%), mercury (9.9%), palladium chloride (7.4%), cobalt chloride (5.0%), and 2-hydroxyethyl methacrylate (5.8%). Positive reactions to metals were frequent in all the different clinical variants, and no specific association between a specific clinical presentation and a particular allergen was found. Allergy to mercury was not a significant factor contributing to the pathogenesis of oral lichenoid reactions. However, a strong association with contact allergy to mercury in dental fillings was found in 2 patients with orofacial granulomatosis.

Apical periodontitis is a chronic inflammatory disorder of periradicular tissues caused by aetiological agents of endodontic origin. Persistent apical periodontitis occurs when root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. Problems that lead to persistent apical periodontitis include: inadequate aseptic control, poor access cavity design, missed canals, inadequate instrumentation, debridement and leaking temporary or permanent restorations. Even when the most stringent procedures are followed, apical periodontitis may still persist as asymptomatic radiolucencies, because of the complexity of the root canal system formed by the main and accessory canals, their ramifications and anastomoses where residual infection can persist. Further, there are extraradicular factors — located within the inflamed periapical tissue — that can interfere with post-treatment healing of apical periodontitis. The causes of apical periodontitis persisting after root canal treatment have not been well characterized. During the 1990s, a series of investigations have shown that there are six biological factors that lead to asymptomatic radiolucencies persisting after root canal treatment. These are: (i) intraradicular infection persisting in the complex apical root canal system; (ii) extraradicular infection, generally in the form of periapical actinomycosis; (iii) extruded root canal filling or other exogenous materials that cause a foreign body reaction; (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues; (v) true cystic lesions, and (vi) scar tissue healing of the lesion. This article provides a comprehensive overview of the causative factors of non-resolving periapical lesions that are seen as asymptomatic radiolucencies post-treatment.

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.

“Over 6 billion pounds per year of the estrogenic monomer bisphenol A (BPA) are used to manufacture polycarbonate plastic products, in resins lining metal cans, in dental sealants, and in blends with other types of plastic products. The ester bond linking BPA molecules in polycarbonate and resins undergoes hydrolysis, resulting in the release of free BPA into food, beverages, and the environment, and numerous monitoring studies now show almost ubiquitous human exposure to biologically active levels of this chemical. BPA exerts estrogenic effects through the classical nuclear estrogen receptors, and BPA acts as a selective estrogen receptor modulator. However, BPA also initiates rapid responses via estrogen receptors presumably associated with the plasma membrane. Similar to estradiol, BPA causes changes in some cell functions at concentrations between 1 pM and 1 nM, and the mean and median range of unconjugated BPA measured by multiple techniques in human pregnant maternal, fetal, and adult blood and other tissues exceeds these levels. In contrast to these published findings, BPA manufacturers persist in describing BPA as a weak estrogen and insist there is little concern with human exposure levels. Our concern with human exposure to BPA derives from 1) identification of molecular mechanisms mediating effects in human and animal tissues at very low doses, 2) in vivo effects in experimental animals caused by low doses within the range of human exposure, and 3) widespread human exposure to levels of BPA that cause adverse effects in animals.”

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.

“Osteonecrosis of the jaws is a recently described adverse side effect of bisphosphonate therapy. Patients with multiple myeloma and metastatic carcinoma to the skeleton who are receiving intravenous, nitrogen-containing bisphosphonates are at greatest risk for osteonecrosis of the jaws; these patients represent 94% of published cases. The mandible is more commonly affected than the maxilla (2:1 ratio), and 60% of cases are preceded by a dental surgical procedure. Oversuppression of bone turnover is probably the primary mechanism for the development of this condition, although there may be contributing comorbid factors. All sites of potential jaw infection should be eliminated before bisphosphonate therapy is initiated in these patients to reduce the necessity of subsequent dentoalveolar surgery. Conservative de´bridement of necrotic bone, pain control, infection management, use of antimicrobial oral rinses, and withdrawal of bisphosphonates are preferable to aggressive surgical measures for treating this condition. The degree of risk for osteonecrosis in patients taking oral bisphosphonates, such as alendronate, for osteoporosis is uncertain and warrants careful monitoring.”