Pharmacokinetics of mercury from dental amalgam

PHARMACOKINETICS OF MERCURY FROM DENTAL AMALGAM Gunilla Sandborgh Englund Dept. of Basal Oral Sciences, Karolinska Institutet, S-141 04Huddinge The overall aim of the present work has been to obtain quantitative and qualitativedata on mercury from dental amalgam in humans. The influence of amalgam removal on mercury levels in blood, plasma and urine hasbeen studied in twelve volunteers. All amalgam fillings were removed during one dentalsession. A transient increase of mercury in blood and plasma was observed within48 h after amalgam removal, and sixty days after the mercury levels in all mediahad decreased to about 60% of the pre removal levels. A bi-exponential model wasapplied on mercury in plasma with the median half-time of the second phase being88 days. The kinetics of mercury in urine was fitted to a mono-exponential model,the median half-time being 46 days. The pharmacokinetics of mercury vapor was studied after a single dose exposurein human volunteers. Nine subjects were exposed to 400 µg/m3 mercury vapor for15 min. The retention was on average 67% of the inhaled mercury dose. A rapid absorptionphase was seen in blood and plasma, followed by a bi-exponential decline. In plasmathe median half-time of the second phase was 10 days with a large inter-individualvariation. The estimated total amount of mercury excreted via urine during 30 daysranged from 8% to 41%. Mercury levels in saliva and feces before and after amalgam removal were studied.The fecal mercury concentrations were more than ten times higher in the pre-removalsamples than those found in a reference group with no amalgam fillings. Two daysafter removal, the fecal mercury concentrations increased about 100 times, followedby a significant decrease. Sixty days after amalgam removal, the mercury levels infeces were still slightly higher than in the reference group. In saliva the medianmercury levels declined from the pre-removal level of 200 nmol/kg to 1 nmol/kg sixtydays after amalgam removal. The kidney is a target organ for inorganic mercury and in animal studies decreasedrenal function has been shown after placement of amalgam fillings. The mercury levelsin blood, plasma and urine and the kidney function were studied before and afteramalgam removal. A number of sensitive renal parameters were determined: the glomerularfiltration rate (GFR) and the excretion of N-acetyl-ß glucose aminidase (NAG),ß2-microglobuline and albumin. No signs of kidney dysfunction were detectable. Effects on mercury levels in blood, plasma and urine after 14-days treatment witha chelating agent (DMSA) or placebo were studied in twenty subjects, relating theirsymptoms to mercury exposure from amalgam fillings. In addition, these effects wererelated to possible changes of symptoms. Three cases of generalized hypersensitivereactions were encountered at the end of the treatment period. A significant increasein urinary mercury excretion was apparent during DMSA treatment, and the blood mercurylevels decreased. There was no evidence that chelating therapy alleviated symptomsallegedly attributable to mercury from amalgam fillings. In summary, amalgam fillings constitute a significant source of exposure to mercury.Mercury levels in blood, plasma, urine, saliva and feces decrease considerably afterthe removal of dental amalgam. No adverse effects on the kidney function were observedfrom the mercury exposure in conjunction with amalgam removal. DMSA treatment appearsto mainly affect the mercury excretion from the kidney, and the risk of hypersensitivityreactions is considerable during prolonged treatment. Combined evaluation of thedecline of mercury in plasma after amalgam removal and after the single dose exposureclearly verifies the pharmacokinetics of mercury as at least tri-exponential. Thepharmacokinetic analysis of mercury verifies the daily mercury dose in subjects withan average number of amalgam fillings to be 5-9 µg per day. Key words: Human, dental amalgam, mercury, blood, plasma, urine, saliva, feces,pharmacokinetics, kidney, chelating agents. ISBN 91-628-2791-

Effects of primary hyperparathyroidism on oral health. A longitudinal register-based study

Objectives: To analyze the effects of primary hyperparathyroidism on oral health and to investigate if the effects are linked to severity of the disease.Subjects and Methods: This prospective cohort study involved 6151 primary hyperparathyroidism patients registered in the Scandinavian Quality Registry of Thyroid, Parathyroid, and Adrenal surgery and the National Cancer Register after parathyroidectomy (exposure) during 2011-2017 (patient cohort) and 60,654 individuals without primary hyperparathyroidism (reference cohort), matched by age, gender, and county of resident at the date of parathyroidectomy. The outcomes were tooth extractions and periodontal interventions. The risk for the outcomes was assessed by Poisson regression models.Results: After adjusting for covariates, the patient cohort had a higher incidence rate of tooth extraction during the two-year period after parathyroidectomy (IRR = 1.15; 95% CI = 1.01-1.31), but a lower incidence rate of periodontal interventions during the four- to six-year period after parathyroidectomy (IRR = 0.88; 95% CI = 0.79-0.99). Furthermore, patients with more severe primary hyperparathyroidism were more likely to have tooth extractions and periodontal interventions after parathyroidectomy.Conclusions: The risk of tooth extraction increased slightly during the first two years after parathyroidectomy. Thereafter, the oral health effects subsided. Pre-surgical serum ionized calcium levels and adenoma weight may indicate negative dental outcomes after parathyroidectomy.Peer reviewe

Consumption and direct costs of dental care for patients with head and neck cancer : A 16-year cohort study

Patients with head and neck (H&N) cancer are commonly treated with surgery and/or radiotherapy, which can increase the risk of oral infection, dental caries, and periodontal disease. The present study investigated dental care consumption and costs in patient with H&N cancer before and after the cancer diagnosis. Data from Swedish regional and national registers were used to follow up dental care utilization and dental procedure costs. The analysis included 2,754 patients who had been diagnosed with H&N cancer (exposed cohort) in Stockholm County, Sweden, during 2000–2012 and 13,036 matched persons without cancer (unexposed cohort). The exposed cohort was sub-grouped into irradiated and non-irradiated patients for analysis. The exposed cohort underwent a moderately higher number of dental procedures per year than the unexposed cohort in both the year of the cancer diagnosis and the year after cancer diagnosis; in addition, these numbers were higher in the irradiated than in the non-irradiated subgroup of the exposed cohort. Dental care consumption and costs in the exposed cohort declined over time but remained at a slightly higher level than in the unexposed cohort over the long term (more than two years). Examinations and preventive procedures accounted for most of the higher consumption in the short term (2 years) and at the longer term follow-up. Swedish national insurance subsidized costs for dental treatment, which were highest in the irradiated subgroup and lowest in the unexposed cohort. Direct costs to the patient, however, were similar among the groups. Swedish national health insurance protects patients with H&N cancer from high dental expenditures. Further studies on the cost-effectiveness of preventive dental care for patients are needed

Longevity of posterior resin composite restorations in adults : a systematic review

Objective: To conduct a systematic review of the literature on the longevity of posterior resin composite restorations in adults. Material and methods: A systematic literature search was conducted according to predetermined criteria for inclusion and exclusion. The studies selected were prospective clinical trials with a minimum follow-up time of 4 years, 40 restorations per experimental group and an annual attrition rate of less than 5%. Initially, abstracts and full-text articles were assessed independently and the assessment was subsequently agreed on by five reviewers. The methodological quality of the studies was assessed according to the Swedish Council on Health Technology Assessment (SBU) standard checklist for determining the extent to which studies meet basic quality criteria. Results: In all, the literature search identified 4275 abstracts and 93 articles were read in fulltext. There were eighteen studies which met the criteria for inclusion, eight of which were included in the analysis. There were 80 failures of restorations with a total follow-up time at risk for failure of 62,030 months. The overall incidence rate for all causes of failure was 1.55 lost restorations per 100 restoration years. The most common biological reason for failure (a total of 31 restorations) was secondary caries, with or without fracture of the restoration. The quality of the evidence was low. Conclusions: In an efficacy setting, the overall survival proportion of posterior resin composite restorations is high. The major reasons for failure are secondary caries and restoration fracture which supports the importance of adequate follow-up time. Clinical significance: The overall survival proportion of posterior composite restorations was high, but the results cannot be extrapolated to an effectiveness setting. The importance of adequate follow-up time is supported by the finding that secondary caries often occurred after 3 years or later. (C) 2015 Elsevier Ltd. All rights reserved

Cognitive changes and neural correlates after oral rehabilitation procedures in older adults: a protocol for an interventional study

Abstract Background Epidemiological studies show an association between masticatory function and cognitive impairment. This has further strengthened the notion that tooth loss and impaired masticatory function may be risk factors for dementia and cognitive decline. Animal experiments have indicated a causal relationship and several possible mechanisms have been discussed. This evidence is, however, lacking in humans. Therefore, in the current interventional study, we aim to investigate the effect of rehabilitation of masticatory function on cognition in older adults. Methods Eighty patients indicated for prosthodontic rehabilitation will be randomly assigned to an experimental or a control group. Participants will conduct neuropsychological assessments, masticatory performance tests, saliva tests, optional magnetic resonance imaging, and answer questionnaires on oral health impact profiles and hospital anxiety and depression scale before, 3 months, and 1 year after oral rehabilitation. The difference between the two groups is that the control group will be tested an additional time, (at an interval of about 3 months) before the onset of the oral rehabilitation procedure. The primary outcome is a change in measures of episodic memory performance. Discussion Although tooth loss and masticatory function are widespread in older people, it is still an underexplored modifiable risk factor potentially contributing to the development of cognitive impairment. If rehabilitation of masticatory function shows positive effects on the neurocognitive function, this will have great implications on future health care for patients with impaired masticatory status. The present project may provide a new avenue for the prevention of cognitive decline in older individuals. Trial registration: The protocol for the study was retrospectively registered in ClinicalTrials.gov Identifier: NCT04458207, dated 02-07-2020

Long-term follow-up: Dental treatment costs (direct costs to the patient and total costs) in the exposed and unexposed cohorts (ANCOVA model)¹.

<p>Long-term follow-up: Dental treatment costs (direct costs to the patient and total costs) in the exposed and unexposed cohorts (ANCOVA model)<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182877#t006fn001" target="_blank">¹</a>.</p

Number of individuals in each cohort in relation to study design.

<p>Number of individuals in each cohort in relation to study design.</p