Mercury

Objectives: The aim of this study was to evaluate the performance of a commercially available chairside amalgam separator (CAS) in a clinical setting in which a relatively high number of amalgam restorations are placed. Performance parameters investigated included service life, amalgam collected, mercury concentrations in effluent, and solids retention efficiency.

Methods and materials: CASs were tested per International Organization of Standardization (ISO) 11143:2008 prior to installation in a military dental treatment facility and after removal from service (n=4) in order to confirm compliance with the recently enacted United States Environmental Protection Agency (EPA) Effluent Limitations Guidelines and Standards for the Dental Category. During the units’ time in service, biweekly effluent grab samples were collected from the high-volume evacuation system of each chair (n=6) and analyzed for total mercury concentration by inductively coupled plasma mass spectrometry (ICP-MS). The mean total accumulated solids at the end of service life (n=6) was determined for potential design optimization. The service life expectancy in a military dental treatment facility was determined in terms of calendar and workdays. Procedural data were collected to determine the daily mean number of amalgam surfaces placed during the service life of each chairside amalgam separator (n=9).

Results: The CAS evaluated met minimum EPA compliance requirements when used in a military dental treatment facility. The solids removal efficiency at the end of service life was 99.82% ± 0.14% (n=4). The mean service life (n=8) was 131.6 ± 45.1 calendar days (67.1±37.6 workdays). Effluent mercury concentrations ranged from 0.05 to 11.93 mg/L. Total solids accumulated in each CAS (n=6) at the end of service life was 195.4 ± 63.4 g. The mean number of amalgam surfaces placed per workday during the service life span of each CAS was 8.4 ± 1.4.

Dental implants are often made of titanium alloys. Implant therapy currently promises a good long-term result without impacting health; however, its success depends on many factors. In this article, the authors focus on the most common risk factors associated with metallic surgical implants. Titanium-induced hypersensitivity can lead to symptoms of implant rejection. Corrosion and biofilm formation are additional situations in which these symptoms may occur. For medical purposes, it is important to define and discuss the characteristics of metals used in implantable devices and to ensure their biocompatibility. To avoid hypersensitivity reactions to metallic dental implants, precautionary principles for primary prevention should be established.

Lichen planus pigmentosus is uncommon in childhood and its treatment is often challenging. We report a case of cutaneous lichen planus pigmentosus in a 10-year-old boy, without oral mucosal involvement, two months after an amalgam dental restoration. The diagnosis was based on the histopathological examination of a skin biopsy, the positive patch test to mercury, and the improvement after amalgam removal. Our case report suggests that metal allergy may play a role, and amalgam replacement may be followed by clinical improvement.

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.

INTRODUCTION:
the biological safety of dental biomaterials has been questioned in human studies.

MATERIAL AND METHODS:
Several heavy metals/oligoelements were compared by Inductive Coupled Mass Spectrometry (ICP-MS) in hair samples from 130 patients (n = 54 patients with long-term titanium dental implants and amalgams (A + I group), 51 patients with long-term dental amalgam alone (A group), as well as controls (n = 25: without dental materials) of similar age. All patients (except controls) had had titanium dental implants and/or dental amalgams for at least 10 years (average: 17). We evaluated whether A + I patients could present higher systemic malondialdehyde levels (MDA) as compared to the A group.

RESULTS:
The A + I group have lower molybdenum levels (A + I) and reduced Mo/Co and Mo/Fe2+ ratios, which could predispose them to oxidative stress by raising MDA levels as compared to the A group alone; our findings suggest that higher Co levels could enhance oxidative stress in the A + I group. However, there were no differences on metals from titanium alloy (Ti-6Al), Cr from crowns or Hg2+, Sn, Zn2+, Cu2+ levels between the A + I and A groups.

CONCLUSION:
patients with long-term dental titanium and amalgams have systemic oxidative stress due to rising MDA levels and lower Mo/Co and Mo/Fe2+ ratios than those with amalgams alone.

PURPOSE:

To evaluate the neurotoxic effect of amalgam dental fillings on plasma mercury (Hg) levels and retino-choroidal layers measured by spectral domain optical coherence tomography (SD-OCT).

MATERIALS/METHODS:

Study participants included 56 cases with amalgam dental fillings and 44 healthy controls. All participants were examined in terms of detailed ophthalmic examination, oral examination, and body mass index (BMI). The measurement of retinal layers and choroid was performed using SD-OCT. Venous blood samples were collected and blood Hg levels were measured using cold vapor atomic absorption spectrometric analysis. Correlations between SD-OCT measurement results and blood Hg levels were analyzed.

RESULTS:

There were no differences between groups in terms of age, sex, or BMI. The mean blood Hg level was 2.76 ± 1.21 µg/L in the amalgam group and 2.06 ± 1.15 µg/L in the control group ( p = 0.04). The Hg/BMI ratio was 0.12 ± 0.06 kg/m2 in the amalgam group and 0.09 ± 0.05 kg/m2 in the control group ( p = 0.01). Reduced volumes of ganglion cell layer and inner plexiform layer were observed in the amalgam group when compared with the control group ( p < 0.05).

CONCLUSION:

Amalgam dental fillings can cause retinal neurotoxicity. SD-OCT can be useful for evaluating amalgam-related retinal neurotoxicity.

Background:

The ubiquitous use of dental amalgam for over 180 years has resulted in the exposure of millions of dental workers to mercury. Dental amalgam contains approximately 50% mercury. Dental workers, including dentists, dental assistants, and dental hygienists, have been shown to have increased levels of mercury and suffer more from health issues related to mercury exposure than the general public. Mercury is known to be absorbed via inhalation or through the skin. There are many routine dental procedures that require the removal of dental amalgam by using the dental high-speed drill, which we suspected generates an occupational mercury exposure that is not sufficiently recognized.

Results:

We showed that drilling dental amalgam generates particulate that volatilizes significant amounts of mercury vapor generally for more than an hour after removal. The levels of mercury vapor created by this procedure frequently exceed the safety thresholds of several jurisdictions and agencies.

Conclusions:

A significant, underrecognized source of localized exposure to mercury vapor was identified in this study. The vapor was created by microgram levels of particulate generated from dental amalgam removal with a high-speed dental drill, even when all feasible engineering controls were used to reduce mercury exposure. This exposure may explain why dental workers incur health effects when safety thresholds are not breached. The dispersion patterns for the particulate are not known, so the use of effective skin barriers and inhalation protection are required during amalgam removal to protect the dental worker from this form of occupational mercury exposure. Standard methodologies for occupational mercury exposure assessment appear to be inadequate when assessing mercury exposure during amalgam removal.

Over the past decades, the use of common sources of electromagnetic fields such as Wi-Fi routers and mobile phones has been increased enormously all over the world. There is ongoing concern that exposure to electromagnetic fields can lead to adverse health effects. It has recently been shown that even low doses of mercury are capable of causing toxicity. Therefore, efforts are initiated to phase down or eliminate the use of mercury amalgam in dental restorations. Increased release of mercury from dental amalgam restorations after exposure to electromagnetic fields such as those generated by MRI and mobile phones has been reported by our team and other researchers. We have recently shown that some of the papers which reported no increased release of mercury after MRI, may have some methodological errors. Although it was previously believed that the amount of mercury released from dental amalgam cannot be hazardous, new findings indicate that mercury, even at low doses, may cause toxicity. Based on recent epidemiological findings, it can be claimed that the safety of mercury released from dental amalgam fillings is questionable. Therefore, as some individuals tend to be hypersensitive to the toxic effects of mercury, regulatory authorities should re-assess the safety of exposure to electromagnetic fields in individuals with amalgam restorations. On the other hand, we have reported that increased mercury release after exposure to electromagnetic fields may be risky for the pregnant women. It is worth mentioning that as a strong positive correlation between maternal and cord blood mercury levels has been found in some studies, our findings regarding the effect of exposure to electromagnetic fields on the release of mercury from dental amalgam fillings lead us to this conclusion that pregnant women with dental amalgam fillings should limit their exposure to electromagnetic fields to prevent toxic effects of mercury in their fetuses. Based on these findings, as infants and children are more vulnerable to mercury exposures, and as some individuals are routinely exposed to different sources of electromagnetic fields, we possibly need a paradigm shift in evaluating the health effects of amalgam fillings.

Context:

Dental offices are known to be one of the largest users of inorganic mercury in the preparation of amalgam-a restorative material which, if not handled and disposed through scientific methods, can pose grave threats to the biosphere.

Aims:

The objective of this study was to assess and record the mercury management and disposal strategies of dental practitioners belonging to the two South Indian states, Kerala and Tamil Nadu.
Subjects and Methods:

A questionnaire regarding the usage and disposal of a filling material containing mercury (amalgam) was designed and distributed online. The 150 dental practitioners partaking in this study responded anonymously.

Results:

The results were statistically analyzed using chi-square test and the P value was evaluated. The usage of amalgam was correlated with the age of the practitioner and the nature of practice and it was found to be statistically significant. The number of fillings was correlated with the years of practice and locality of the clinic, which were found to be statistically significant.

Conclusions:

This study showed that mercury was widely preferred and utilized even today as a restorative material by dentists and dental specialists, despite the availability of other alternative strategies. Only a minor section of practitioners were found to be aware of the global changes in the guidelines pertaining to the handling and disposal of amalgam. We feel that Safe Mercury Amalgam Removal Technique, amalgam safety rules, and amalgam-free practice should be a part of the academic curriculum and continuing dental education.

The Minamata Convention on Mercury is an international environmental treaty. In 2013, the United States became one of the 128 governments to become signatories on the Minamata Convention. The Convention entered into force in August 2017. Among its many goals, the Convention articulates in Annex A the phasing down of the use of dental amalgam. The American Dental Association (ADA) supports the Minamata Convention and, with respect to amalgam use, advocates promoting strategies to prevent dental disease and investing in development of fully effective alternatives to dental amalgam. The third meeting of parties to the Minamata Convention is scheduled to take place at the end of November 2019. Among the potential items on the agenda is the review of Annex A and a consideration of whether the previously agreed-to phase down should instead be revised to a phase out of amalgam by 2024dthat is, a complete ban of amalgam across the world. If revised, this will lead to decisions that will affect dental treatment alternatives and waste management of mercury stemming from the removal of existing amalgam restorations. Although 2024 may be when dentists will stop placing amalgam, the impact on the environment will need to be managed for many more years to come, and most countries are not technically or financially prepared for that change in practice.