Mercury vapour exposure during dental student training in amalgam removal

Environmental and genetic predictors of whole blood mercury and selenium concentrations in pregnant women in a UK birth cohort

There is evidence that tissue concentrations of mercury (Hg) and selenium (Se) are predicted by numerous dietary, sociodemographic, environmental, and genetic factors. This study aimed to estimate the relative importance of predictors of Hg and Se concentrations in blood samples taken from pregnant women. The Avon Longitudinal Study of Parents and Children (ALSPAC) in the UK measured whole blood Hg and Se concentrations in 3,972 pregnant women. We identified 30 potential predictors of Hg and 24 of Se, which were evaluated using cross-validated random forests to identify the optimal models for predictive power. The relative importance of individual variables was estimated by averaging the added-R2 per predictor. Linkage disequilibrium score regression was used to estimate the variance explained by genotype. A multivariable model of 14 predictors explained 22.4% of Hg variance (95% CI: 13.0 to 37.1), including 6.9% from blood Se and 3.2% from white fish consumption. There were 11 predictors which explained 15.3% of Se variance (CI: 8.9 to 25.9), including 6.4% from blood Hg, 1.3% from blood lead, and 1.3% from oily fish. Measured genetic variation explained 30% of Hg variance (CI: 8.4 to 51.5) and 37.5% of Se (CI: 10.4 to 64.5). A high proportion of Hg and Se variance could be explained from dietary, sociodemographic, metabolic, and genetic factors. Seafood consumption was less predictive of Hg than may be expected and other factors should be considered when determining risk of exposure. There was tentative evidence that genotype is a major contributor to Hg and Se variation, possibly by modifying the efficacy of internal metabolism.

Analyzing Content and Quality of YouTube™ Videos on Removal of Amalgam Fillings

Objective. The objective of this study was to analyze the information quality and content of operational videos available on YouTube™ regarding amalgam fillings removal. Methods. Videos were determined using the words “Removal of amalgam fillings” and “Replacement of amalgam fillings” in the YouTube™ search section. 85 videos were included for analysis. Demographics of videos, viewers’ interactions, and viewing rates were evaluated. The videos were analyzed in two parameters in terms of Audio-visual quality and the SMART (Safe Mercury Amalgam Removal Technique) protocol steps. Results. It was determined that dentists accounts ranked first (62%) in the distribution of video sources. While only 19% of the videos were of “Excellent” audio-visual quality, 49% were rated as “Moderate” and 33% were rated as “Poor”. In the SMART evaluation, while only 10% of the videos got the “Maximal Useful” score, the majority of the videos got the “Slightly Useful” score (58%). There was no statistical relationship between the “View Rate” and “Interaction Index” variables of the videos (p> 0.05). Conclusions. Operational videos about the removal of dental amalgam fillings should be uploaded to YouTube™ after approval by the experts of the subject. Students should be warned about videos which contain insufficient information. Videos should be prepared in line with current information in the literature.

Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams

Mercury is produced and drained into the environment by removing dental amalgams, which may cause mercury pollution. This study aimed to clarify the mercury amount remaining in the oral cavity and inside the drain system after removal. The effects of the removal conditions and differences in drainage systems were also investigated. Dental amalgams filled in the tooth and placed in a phantom head were removed using an air turbine under several conditions (two removal methods, absence of cooling water, and intraoral suction). Then, the oral cavity was rinsed with 100 mL of water (oral rinse water), and 500 mL of water was suctioned to wash the inside of the drainage system (system rinse water). Both water samples were collected in two ways (amalgam separator and gas-liquid separator), and their mercury amounts were measured. It was found that the amount of mercury left in the oral cavity and drainage system after dental amalgams removal could be reduced when the amalgams were removed by being cut into fragments as well as using cooling water and intraoral suction. In addition, using amalgam separators can significantly reduce the amount of mercury in the discharge water and prevent the draining of mercury into the environment.

Managing the phase-down of amalgam amongst Nigerian dental professionals and students: A national survey

BACKGROUND

Amalgam is one of the most reliable dental restorative materials. Health and environmental concerns associated with the mercury content of amalgam have necessitated an amalgam phase-down in clinical practice.

OBJECTIVES

This study investigated the level of awareness and preparedness for the planned amalgam phase-down recommended by the Minamata Convention amongst Nigerian dental students and dentists.

METHODS

This cross-sectional national survey was performed across all geopolitical zones of Nigeria. Data regarding awareness, practice and level of preparedness for amalgam phase-down were obtained using a questionnaire that was distributed amongst clinical dental students and dentists of different cadres, who routinely place dental restorations, in public and private practice. The questionnaires were administered online or were hand delivered. Data were analysed using the chi-square test and Spearman's rank correlation coefficient. A p value ≤ 0.05 was considered statistically significant.

RESULTS

Notably, 845 dental students and dentists participated in the survey. Mean age (±standard deviation) of participants was 30.15 ± 7.67 years, 33.8% were students, and 66.2% were dentists (most dentists [77.1%] were employed at public hospitals). A significant percentage of respondents had poor knowledge of the Minamata Convention (87.7%) and lacked training in the use of alternatives to amalgam (72.0%). Amalgam continues to be commonly used by 39.1% and 31.3% of dental students and dentists, respectively. Only 4.7% of the respondents admitted to following good amalgam phase-down practices. Awareness (P = 0.013) and amalgam phase-down practices (P = 0.011) were significantly higher amongst dentists than amongst dental students.

CONCLUSION

We observed low levels of awareness regarding the Minamata Convention, amalgam phase-down, mercury hygiene practices and training in alternatives to amalgam use amongst Nigerian dental professionals and students.

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.

Mercury vapor volatilization from particulate generated from dental amalgam removal with a high-speed dental drill - a significant source of exposure

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.

Dental caries in the peruvian police population

Background

Dental caries is a multifactorial disease that affects the general population. After reviewing the scientific literature, no studies were found on the index of decayed, missing and filled teeth (DMFT) in the Peruvian police population. The objective was to evaluate the DMFT index and severity level of the disease in police personnel of the Ancash region, Peru.

Material and Methods

Cross-sectional prevalence study. The medical records of the police personnel in activity were reviewed and each subject was examined from May 2012 to May 2013. The study was authorized by the Director of the PNP-Huaraz Ancash Polyclinic as part of the activities of the civil SERUMS personnel in the area of odontology. The sample was census with 925 subjects. The data was systematized following the methodology recommended by the World Health Organization (WHO). The statistics were analyzed by Chi square test with significance p<0.05, Pearson test and ANOVA.

Results

The prevalence of caries in the police population was 73.4%. The DMFT index was 10.63 ± 4.96 (p<0.01). The severity of the disease in relation to age was 0.77 ± 0.41 with a high risk in this population. The DMFT index in females 128/925 and males 797/925 was 10.43 and 10.67 respectively. There is an inversely proportional relationship in the number of teeth filled with dental amalgam in policemen older than 35 years versus the number of teeth sealed with material other than dental amalgam in policemen under 35 years. Only 0.8% 7/925 had dental prostheses and 58.6% (542/925) of the subjects needed oral rehabilitation.

Conclusions

The severity of dental caries is high, strategies are required to improve intervention in this sector, developing effective programs in oral health in the short, medium and long term.

Key words:Dental caries severity, oral health, dental caries prevalence, peruvian police.

Phase down of amalgam. Awareness of Minamata convention among Jordanian dentists

OBJECTIVES

To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites.  Methods: This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite.  Results: Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists' decision to remove old amalgam based on patient's demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion: Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education.

Impacts of Mercury Pollution Controls on Atmospheric Mercury Concentration and Occupational Mercury Exposure in a Hospital

Mercury (Hg) and Hg-containing products are used in a wide range of settings in hospitals. Hg pollution control measures were carried out in the pediatric ward of a hospital to decrease the possibility of Hg pollution occurring and to decrease occupational Hg exposure. Total gaseous Hg (TGM) concentrations in the pediatric ward and hair and urine Hg concentrations for the pediatric staff were determined before and after the Hg pollution control measures had been implemented. A questionnaire survey performed indicated that the pediatric staff had little understanding of Hg pollution and that appropriate disposal techniques were not always used after Hg leakage. TGM concentrations in the pediatric ward and urine Hg (UHg) concentrations for the pediatric staff were 25.7 and 22.2% lower, respectively, after the Hg pollution control measures had been implemented than before, which indicated that the control measures were effective. However, TGM concentrations in the pediatric ward remained significantly higher than background concentrations and UHg concentrations for the pediatric staff were remained significantly higher than the concentrations in control group, indicating continued existence of certain Hg pollution.