The Hazardous Effects of Dental Amalgam Fillings in Human Body: A Systematic Review

The Dental amalgam used in the dental fillings is basically an alloy of mercury (Hg). The amalgam is one of the most commonly used and versatile restorative material. Since more than 150 years this alloy of mercury, that is amalgam is used for it been economical, easy to use, durable, high strength and bacterio-static characteristics. Due to environmental pollution, detrimental health its use is decreasing in recent times. Also its not so appealing like the other materials used that resemble the tooth color. The tooth coloured restorative materials are recommended by both the doctor and the patient. Many researchers suggested that over the period of time the mercury from the filling might leach into the mouth. Thus in this study a detailed review of all the literature available online is done to understand the hazardous effects of dental amalgam fillings in the human body. The systematic literature search using Scopus, PubMed, EMBASE and Web of Science electronic databases was done using PRISMA. The experiments conducted in Sheep and monkey suggested the penetration of amalgam into the jaw bone of the patient with dental restorations. Constant exposure of mercury at lower levels can also lead to multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosus. Most commonly reported renal dysfunction due to the dental amalgams are Tubular and Glomerular damage of the kidneys.

Validity and responsiveness of EQ-5D-5L and SF-6D in patients with health complaints attributed to their amalgam fillings: a prospective cohort study of patients undergoing amalgam removal

Background Evidence of health utility changes in patients who suffer from longstanding health complaints attributed to dental amalgam fillings are limited. The change in health utility outcomes enables calculating quality-adjusted life-year (QALY) and facilitates the comparison with other health conditions. The purpose of this study was to estimate the validity and responsiveness of the EQ-5D-5L and SF-6D utilities following removal of dental amalgam fillings in patients with health complaints attributed to their amalgam fillings, and examine the ability of these instruments to detect minimally important changes over time. Methods Patients with medically unexplained physical symptoms, which they attributed to dental amalgam restorations, were recruited to a prospective cohort study in Norway. Two health state utility instruments, EQ-5D-5L and SF-6D, as well as self-reported general health complaints (GHC-index) and visual analogue scale (EQ-VAS) were administered to all patients (n = 32) at baseline and at follow-up. The last two were used as criteria measures. Concurrent and predictive validities were examined using correlation coefficients. Responsiveness was assessed by the effect size (ES), standardized response mean (SRM), and relative efficiency. Minimally important change (MIC) was examined by distribution and anchor-based approaches. Results Concurrent validity of the EQ-5D-5L was similar to that of SF-6D utility. EQ-5D-5L was more responsive than SF-6D: the ES were 0.73 and 0.58 for EQ-5D-5L and SF-6D, respectively; SRM were 0.76 and 0.67, respectively. EQ-5D-5L was more efficient than SF-6D in detecting changes, but both were less efficient compared to criteria-based measures. The estimated MIC of EQ-5D-5L value set was 0.108 and 0.118 based on distribution and anchor-based approaches, respectively. The corresponding values for SF-6D were 0.048 and 0.064, respectively. Conclusions In patients with health complaints attributed to dental amalgam undergoing amalgam removal, both EQ-5D-5L and SF-6D showed reasonable concurrent and predictive validity and acceptable responsiveness. The EQ-5D-5L utility appears to be more responsive compared to SF-6D. Trial registration The research was registered at ClinicalTrials.gov., NCT01682278. Registered 10 September 2012, https://clinicaltrials.gov/ct2/show/NCT01682278.

Dental amalgam risks in dental staff: systematic review

Mercury is an essential constituent of dental amalgams, several studies have shown that dental personnel who work with dental amalgams are chronically exposed to mercury vapors. The World Health Organization considers that inhaling mercury vapors can have harmful effects on the nervous, immune, pulmonary and renal systems. The objective of this review was to collect and analyze data relating to the exposure of dental personnel to mercury and the possible harmful effects on human health. All biomonitoring studies published between 2002 and 2019 measuring mercury in hair, blood, urine and nails were included. Dentists reported higher levels of mercury in their biomarkers compared to control groups. These levels reflected occupational exposures to chronic low levels of elemental mercury in dental amalgam fillings. Some studies have shown a high prevalence of neurological symptoms and memory deficit in dental staff compared to controls. Studies based on genes involved in mercury metabolism have shown associations between sources of mercury exposure and single nucleotide polymorphisms in these genes. It is important that preventive measures are strengthened to reduce exposure to mercury and that a biomonitoring program for dental professionals exposed to mercury vapors is implemented.

Mercury Exposure Assessment in Mother–Infant Pairs from Continental and Coastal Croatia

The main source of mercury (Hg) exposure in the general population is fish. Another possible source is dental amalgam. Here, we compare the levels of Hg and selenium (Se) in samples of maternal and fetal origin collected shortly after childbirth of healthy postpartum women in the coastal (n = 96) and continental (n = 185) areas of Croatia related to maternal seafood/fish consumption. We also evaluated Hg concentrations and maternal serum metallothionein (MT2) concentrations in relation to the number of dental amalgam fillings, and MT2A-5A/G (rs28366003) polymorphism. The levels of Hg and Se in maternal hair and blood/serum, placenta and cord blood/serum increased in relation to increasing fish consumption with the highest values in subjects from the coast. The concentrations of each element and between elements correlated across the matrices. Increasing amalgam number correlated linearly with increased Hg levels in maternal and cord serum and was not associated with serum MT2. No association of MT2A-5A/G polymorphism and Hg or Se levels were found. The results confirmed higher fish consumption in coastal vs. continental Croatia and increases of both Hg and Se related to fish consumption in all analyzed samples. Increased blood Hg reflected the predominant MeHg share from seafood, while increased serum Hg matched exposure from dental amalgams.

Dental Amalgam Fillings and Multiple Sclerosis: A Nationwide Population-Based Case–Control Study in Taiwan

Multiple sclerosis (MS) is an inflammatory neurological disease characterized by autoimmune-mediated demyelination of the central nervous system. Genetic and environmental factors may contribute to the development of MS. This has not been confirmed yet. Dental amalgam has long been controversial in MS due to its mercury content but the toxicological implications of mercury-containing amalgam fillings (AMF) for MS remain to be elucidated. We conducted a case–control study to investigate the association between AMF and the risk of MS from the Taiwanese National Health Insurance Research Database (NHIRD). Case (n = 612) and control (n = 612) groups were matched by sex, age, urbanization level, monthly income, and Charlson comorbidity index by propensity score matched with a 1:1 ratio from 2000 to 2013. Differences between cases and controls was not statistically significant (OR: 0.82, 95% CI = 0.65–1.05). In subjects stratified by gender, MS was also not associated with AMF for women (OR: 0.743, 95% CI = 0.552–1.000) and men (OR: 1.006, 95% CI = 0.670–1.509), respectively. In summary, this Taiwanese nationwide population-based case–control study did not find an association between MS and AMF.

Elevated Systemic L-Kynurenine/L-Tryptophan Ratio and Increased IL-1 Beta and Chemokine (CX3CL1, MCP-1) Proinflammatory Mediators in Patients with Long-Term Titanium Dental Implants

Titanium is the mean biocompatible metal found in dental titanium alloys (Ti-6Al-4V). The safety of certain dental biomaterial amalgams has been questioned in patients. The levels of several systemic cytokines (interleukin (IL)-1 beta, IL-4: pg/mL) and chemokines (monocyte chemoattractant protein-1 (MCP-1), soluble fractalkine (CX3CL1: pg/mL) were determined using ELISA and compared between these study groups. The study included 30 controls without dental materials (cont), 57 patients with long-term titanium dental implants plus amalgams (A + I group) as well as 55 patients with long-term dental amalgam alone (A group). All patients (except controls) have had dental titanium implants (Ti-6Al-4V) and/or amalgams for at least 10 years (average: 15 years). We evaluated whether systemic levels of cytokines/chemokines, kyn/L-trp ratio and aromatic amino acid levels (HPLC: mM/L, Phe, L-Trp, His, Treo) could be altered in patients with long-term dental titanium and/or amalgams. These systemic markers were evaluated in 142 patients. The A + I group had higher L-Kynurenine/L-Tryptophan ratios than patients with long-term dental amalgam fillings alone (A). In addition, levels of IL-1 Beta cytokine, CX3CL1 and MCP-1 chemokines were higher in the A + I group than in the A group (A). The increased L-kyn/L-trp ratio and MCP-1 and fractalkine receptor (CX3CR1) elevations could suggest enhanced chemotactic responses by these chemokines in the A + I group.

Rethinking the Dental Amalgam Dilemma: An Integrated Toxicological Approach

Mercury (Hg) has been identified as one of the most toxic nonradioactive materials known to man. Although mercury is a naturally occurring element, anthropogenic mercury is now a major worldwide concern and is an international priority toxic pollutant. It also comprises one of the primary constituents of dental amalgam fillings. Even though dental mercury amalgams have been used for almost two centuries, its safety has never been tested or proven in the United States by any regulatory agency. There has been an ongoing debate regarding the safety of its use since 1845, and many studies conclude that its use exposes patients to troublesome toxicity. In this review, we present in an objective way the danger of dental amalgam to human health based on current knowledge. This dilemma is addressed in terms of an integrated toxicological approach by focusing on four mayor issues to show how these interrelate to create the whole picture: (1) the irrefutable constant release of mercury vapor from dental amalgams which is responsible for individual chronic exposure, (2) the evidence of organic mercury formation from dental amalgam in the oral cavity, (3) the effect of mercury exposure on gene regulation in human cells which supports the intrinsic genetic susceptibility to toxicant and, finally, (4) the availability of recent epidemiological data supporting the link of dental amalgams to diseases such as Alzheimer’s and Parkinson.