Multiple sclerosis, dental caries and fillings: a case-control study

Increased Risk for Acute Periapical Abscesses in Multiple Sclerosis Patients and the Possible Association with Epstein-Barr Virus

INTRODUCTION

Multiple sclerosis (MS) is a severe inflammatory neuroimmune degenerative condition affecting more than 2 million individuals worldwide. The purpose of this study was to assess the prevalence of acute periapical abscesses in patients with MS and to evaluate whether acute periapical abscesses (PAs) are more likely to affect patients who were previously infected by Epstein-Barr virus (EBV).

METHODS

Integrated data of hospital patients were used. Data from the corresponding diagnosis codes for MS and acute PA were retrieved by querying the appropriate International Classification of Diseases, Tenth Revision codes in the database.

RESULTS

Of the total hospital patient population, 0.18% were diagnosed with a history of MS. Females were more affected than males 3.25-fold. Whites were more affected than African Americans 6-fold. Whites were more affected than African Americans combined with other ethnicities 3.6-fold. The odds ratio (OR) for acute PAs in patients with a history of MS was 2.2 (P < .0001). After adjustment for diabetes mellitus comorbidity, the OR for acute PAs in patients with a history of MS was 2.6. After adjustment for cardiovascular disease comorbidity, the OR for acute PAs in patients with a history of MS was 1.27. Of the patients who presented with PAs, 0.2% were diagnosed with a history of EBV infection. The OR was 3.98, and the difference in prevalence was statistically significant (P < .0001).

CONCLUSIONS

Under the conditions of this cross-sectional study, it appears that the prevalence of acute PAs is higher in patients with MS and that EBV may play a role.

Potentially toxic elements in the brains of people with multiple sclerosis

Potentially toxic elements such as lead and aluminium have been proposed to play a role in the pathogenesis of multiple sclerosis (MS), since their neurotoxic mechanisms mimic many of the pathogenetic processes in MS. We therefore examined the distribution of several potentially toxic elements in the autopsied brains of people with and without MS, using two methods of elemental bio-imaging. Toxicants detected in the locus ceruleus were used as indicators of past exposures. Autometallography of paraffin sections from multiple brain regions of 21 MS patients and 109 controls detected inorganic mercury, silver, or bismuth in many locus ceruleus neurons of both groups, and in widespread blood vessels, oligodendrocytes, astrocytes, and neurons of four MS patients and one control. Laser ablation-inductively coupled plasma-mass spectrometry imaging of pons paraffin sections from all MS patients and 12 controls showed that combinations of iron, silver, lead, aluminium, mercury, nickel, and bismuth were present more often in the locus ceruleus of MS patients and were located predominantly in white matter tracts. Based on these results, we propose that metal toxicants in locus ceruleus neurons weaken the blood-brain barrier, enabling multiple interacting toxicants to pass through blood vessels and enter astrocytes and oligodendroglia, leading to demyelination.

Dental amalgams and risk of gestational hypertension in the MIREC study

BACKGROUND

The potential association between the presence or replacement of dental amalgams and gestational hypertension (GH) is unclear.

OBJECTIVE

To assess the association between the presence or replacement of dental amalgams and the risk of GH in a prospective cohort study.

METHODS

We assessed dental amalgam status (presence or replacement), blood mercury concentrations, and measured blood pressure (BP) in 1817 pregnant women recruited in 10 Canadian cities. BP was assessed in each trimester of pregnancy and mercury concentrations in 1st and 3rd trimesters. Logistic regression analysis was performed to estimate the adjusted odds ratios (aOR) and 95% confidence intervals (CI) for the associations between dental amalgam status and GH. Concurrent measures with systolic BP (SBP) and diastolic BP (DBP) were assessing through linear generalized estimating equations.

RESULTS

Dental amalgam status was weakly statistically correlated with mercury concentrations but there was no evidence of an association with GH in women having 1-4 (aOR = 1.31 (0.92, 1.85)) or ≥ 5 dental amalgams (aOR = 1.32 (0.86, 2.04)), compared to women without amalgam reported at first trimester. Dental amalgam replacement reported in the first or third trimester was similarly not associated with GH (aOR = 0.75 (0.40, 1.42) and 0.73 (0.39, 1.34), respectively) but with SBP (beta = -1.58 (-2.95, -0.02)).

CONCLUSION

We found weak correlations between dental amalgams and blood mercury among pregnant women. However, the presence of dental amalgams or their replacement was not associated with GH but with decreased SBP for the replacement. Further studies are required.

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.

A systematic review of oral health in people with multiple sclerosis

OBJECTIVES

Despite more than 25 years of research focused on this topic, it remains unclear whether people with multiple sclerosis are more likely to present with oral health problems. The aim of this study was to provide the first systematic review of this literature.

METHODS

A literature search for studies focused on oral health and multiple sclerosis was conducted using PRISMA guidelines. Electronic databases (PubMed, Scopus, Web of Science, MEDLINE and CINAHL) were searched up until February 2019. Two independent coders extracted data, and study quality graded using the Newcastle-Ottawa Scale (NOS).

RESULTS

From 1281 articles identified, 17 met all the eligibility criteria. Of the seventeen studies, more than half included a nonclinical control group, and the majority were observational studies. The included studies were of poor to moderate quality. Taken together, the results provided only very limited evidence that people with multiple sclerosis are more likely to present with dental caries and gingival disease. There was suggestive evidence that people with multiple sclerosis may be at higher risk of periodontal disease and present with poorer oral hygiene, and moderate evidence for an association between multiple sclerosis and temporomandibular disorders.

CONCLUSIONS

This systematic review provides evidence of an association between multiple sclerosis and at least some oral health problems. When temporomandibular disorders and periodontal status specifically have been assessed, most studies provide evidence of an association with multiple sclerosis. However, this review also clearly highlights the need for further, high-quality studies in this area.

Investigating the relationship between multimorbidity and dental attendance: a cross-sectional study of UK adults

Introduction

Regular dental attendance is related to better oral health. However, long-standing health conditions (LSHCs) may be related to dental attendance and this relationship may vary by socioeconomic status.

Method

Data were collected from wave two (2013–2015) of the Yorkshire Health Study (n= 7,654). Data included dental attendance, LSHC, age, gender, education-level, smoking, body mass index, and area-level deprivation. Logistic regression (attend or not) was used to analyse associations with LSHC and multimorbidity.

Results

Overall, 63.1% (n = 4,826) of individuals attended the dentist. Of these, 37.8% (n =2894) had no LSHC, 26.0% (n = 1987) had one LSHC and 36.4% (n = 2784) had two or more LSHC. The presence of a singular LSHC was not associated with dental attendance(OR = 0.91 [0.81, 1.04]), however, those with two or more LSHCs were more likely to attend the dentist (OR = 0.81 [95% CI 0.72, 0.92]). Interactions between individual-level education, as a marker of socioeconomic status, and LSHC revealed few associations with dental attendance.

Conclusion

Multimorbidity was associated with dental attendance such that those with multimorbidity were more likely to attend. These important findings highlight the increasing challenge of multimorbidity for global healthcare systems.

Oral health and behaviours of people living with Multiple Sclerosis in Australia

OBJECTIVES

The literature describing the oral health of people with Multiple Sclerosis (MS) is scant and the findings equivocal. The aim of this study was to describe the oral health and oral self-care behaviours of people living with MS and compare it to the Australian population.

METHODS

Participants enrolled with the Australian MS Longitudinal Study (AMSLS) were invited to participate in the survey using an online or paper-based questionnaire. Data were collected on level of disability, oral health, oral self-care and factors influencing attendance for oral health care.

RESULTS

Completed questionnaires were received for 1523 respondents. Over one-fifth (n = 320; 22%) rated their oral health as fair or poor, and more than half (n = 840; 57%) reported toothache in the last 12 months. These proportions were higher than those for the general Australian adult population (oral health prevalence ratio (PR) = 1.25 [1.12, 1.40]; toothache PR = 3.63 [3.39, 3.88]), and this is despite comparable or better self-maintenance habits and dental attendance reported by respondents. People with MS reported high rates of mouth dryness (68.4%), teeth sensitivity (64.7%), change of taste (40.5%) and orofacial pain (39.0%); fewer than 10% experienced none of these. There was a lower prevalence of self-reported need for treatment (extraction or filling) than in the Australian adult population (15.8% vs 32.9%).

CONCLUSIONS

People with MS have a greater oral health burden, demonstrated by their poorer self-reported oral health than the Australian adult population. Furthermore, they experience high rates of toothache, mouth dryness, teeth sensitivity, change of taste and orofacial pain. These findings are contrary to their self-reported good oral self-care and dental attendance habits and suggest some of the oral health impacts are due to MS rather than dental behaviours.

Blood lead levels and multiple sclerosis: A case-control study

BACKGROUND

Multiple sclerosis (MS) is a debilitating disease of the central nervous system, with disseminating demyelination of nerve fibers and spinal cord. Exposure to heavy metals seems to be associated with a higher incidence of MS. Few studies have assessed the correlation of the incidence of MS with heavy metal concentrations. The present study aimed to assess the relationship between blood lead levels and MS.

METHODS

This case-control study was conducted on 29 MS patients and 29 healthy control persons. The controls were age, gender and occupation matched at the time of blood sampling. Blood lead levels were measured using the atomic absorption spectrometry method. Data were analyzed using Student t-test, Mann-Whitney U, and multiple logistic regression, using a significance level of p ˂ 0.05.

RESULTS

According to the result of this study, the mean blood lead level (BLL) was 75.6 ± 9.35and33.8 ± 28.8 µg/L in patients with MS and control group, respectively. Median blood lead levels were significantly higher in MS patients (38 µg/L, range: 27-67), compared to the controls (30 µg/L, range: 11-49) (p = 0.03). The risk of MS increased 1.17 times per one µg/L increment of blood lead level, using the multiple logistic regression analysis on the present results.

CONCLUSION

In conclusion, based on our results, BLL was higher in MS patients, compared with healthy individuals. The risk of MS increased 1.17 times per one µg/L increment of blood lead level.

Expanded Disability Status Scale-Based Disability and Dental-Periodontal Conditions in Patients with Multiple Sclerosis

OBJECTIVE

The aim of this study was to evaluate the association between different disability states in patients with multiple sclerosis (MS) as determined by the expanded disability status scale (EDSS) and dental-periodontal measures.

SUBJECTS AND METHODS

Eighty patients with MS (64 females and 16 males) were included in this study. Data on MS types, attack frequency, disease duration, EDSS scores and orofacial complaints prior to an MS attack were obtained from medical records. The plaque index (PI), probing depth (PD), clinical attachment level (CAL), gingival index (GI), decayed-missing-filled teeth (DMFT) index and number of present teeth were measured during one dental examination for each subject. The MS patients were divided into the following 2 groups based on their EDSS scores: low physical disability (L-DS) and high physical disability (H-DS). Differences in dental parameters between groups of low and high disability were investigated. p < 0.05 was considered statistically significant.

RESULTS

The mean age of the participants was 38.06 ± 10.11 years. Age and disease duration were higher in the H-DS MS group than in the L-DS MS group (p < 0.05). The PI, PD and GI were higher and the number of filled teeth was lower in the H-DS MS group than in the L-DS MS group (p < 0.05). The EDSS scores of the H-DS MS group presented a significant correlation with the number of decayed teeth (r = -0.548, p = 0.005). Orofacial complaints prior to an MS attack were reported by 18 (22.5%) patients.

CONCLUSION

Oral measurements revealed various differences between groups of low and high disability in MS patients. In addition, some maxillofacial-oral complaints prior to an MS attack were observed.

The epidemiology of multiple sclerosis: insights to disease pathogenesis

The purpose of studying the epidemiology of multiple sclerosis (MS) is twofold. First, it is important to understand clearly the natural history of the illness in order to assist patients in making decisions about their future with respect to issues such as family planning, the importance of securing lifelong healthcare, their ability to get and maintain employment, and making appropriate choices of therapy for their particular circumstances. This is not to suggest that, even with the best possible information, the ultimate prognosis for any individual can be predicted with absolute accuracy. It cannot. Nevertheless, accurate information can be very helpful both to reassure patients that many individuals with MS do remarkably well in the long term (perhaps, especially, with current and future therapies) and also to empower individuals with respect to their ability to make their own life choices. Second, and arguably the more important purpose for studying the epidemiology of MS, is to gain insights to the underlying causes of the disease. Indeed, if the principal mechanisms of disease pathogenesis were to be understood clearly, then it might be possible to entertain notions of either a cure for existing disease or the primary prevention of future disease. Much of our current understanding of disease pathogenesis, as discussed in other chapters of this volume, has been derived from basic science investigations of animal models of MS such as experimental autoimmune encephalomyelitis (EAE), and these models have provided considerable insight both to the complexity of the mammalian immune system and to the mechanisms underlying its dysfunction in inflammatory autoimmune conditions. Nevertheless, MS is a disease of humans without any known, naturally occurring, counterpart in any nonhuman species. For this reason, the clues to disease pathogenesis provided by a study of basic epidemiologic facts regarding MS (and by a systematic consideration of their implications) are essential to a comprehensive understanding of the human illness we call MS.

Impact of oral health in patients with multiple sclerosis and epilepsy: a survey in a neurology clinic

This study investigated the impact of oral health on neurological disorders using the Oral Health Impact Profile (OHIP). A total of 460 subjects completed the OHIP, including 141 control subjects who did not have any neurological conditions. Of the 319 subjects with a neurological diagnosis who were enrolled in the study, 31% had multiple sclerosis (MS), 34% had epilepsy, and 34% had other neurological conditions. Compared to the control group, mean age (p = .001), education (p = .003), and household income levels (p ≤ .001) were statistically significantly lower among subjects with epilepsy than in the other two groups. The majority of the study populations were Caucasian and the percentage was highest in those with MS (87%). Patients with any neurologic diagnosis had greater physical pain and disability than controls. Adjusting for demographic variables, the impact of physical disability was statistically significantly higher in patients with any neurological diagnosis (including MS and epilepsy) (OR = 4.49). In multinomial regression, the strongest association of physical disability impact was noted in patients with epilepsy (OR = 5.17). The physical disability domain of the OHIP is more commonly associated with a neurological diagnosis, including MS, and the association is strongest in patients with diagnosis of epilepsy.

Serum mercury level and multiple sclerosis

Exposure to heavy metals has been associated to a higher incidence of multiple sclerosis. In this work, we present a possible relationship between serum mercury levels and development of multiple sclerosis in Isfahan, the third largest city in Iran. Seventy-four patients affected by multiple sclerosis were retrieved from multiple sclerosis (MS) clinic in Isfahan, Iran. By matching sex and age, 74 healthy volunteers were chosen as control group. Blood samples were collected and serum mercury content was determined. Serum mercury level in MS patients was significantly higher than controls (9.6 ± 10.17 vs. 5.7 ± 8.6, P = 0.037). Concerning all MS patients, serum mercury value was significantly higher than the mercury concentration founded in control subjects {odd ratio: 2.39 (CI, 1.96-2.94), P = 0.00}. Serum mercury level is higher in MS patients with odd ratio equal to 2.39 compared with healthy individuals. It may reveal that high mercury levels in serum might help MS development in susceptible individuals. More studies with larger sample size are needed to confirm this hypothesis.

Oral health status of a population with multiple sclerosis

Objective: To determine the oral treatment needs of a sample of patients diagnosed with multiple sclerosis in the Community of Madrid (Spain). Patients and methods: A cross-sectional epidemiological study was carried out with a sample of 64 patients who were aged 25 to 77 years. They were distributed into homogeneous age groups: < 46 years, 46-54 years and > 54 years. In order to evaluate the oral health status and treatment requirements, the parameters and guidelines of the WHO were used. Results: The prevalence of caries was 100%, or very close in all three groups. As age increased, the morbidity rate decreased, but the mortality rate increased considerably. On analyzing gingival health, 65% of patients had calculus, 5% bleeding and 30% were healthy. Conclusions: The DMFT index found provided data that was, in general, very similar to that of the general population in Spain. However, the gingival health status found demonstrated that the population of multiple sclerosis patients requires specific assistance.

Key words: Multiple sclerosis, oral health, dentures.

Is dental amalgam safe for humans? The opinion of the scientific committee of the European Commission

It was claimed by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR)) in a report to the EU-Commission that "....no risks of adverse systemic effects exist and the current use of dental amalgam does not pose a risk of systemic disease..." [1, available from: http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_016.pdf].SCENIHR disregarded the toxicology of mercury and did not include most important scientific studies in their review. But the real scientific data show that:(a) Dental amalgam is by far the main source of human total mercury body burden. This is proven by autopsy studies which found 2-12 times more mercury in body tissues of individuals with dental amalgam. Autopsy studies are the most valuable and most important studies for examining the amalgam-caused mercury body burden.(b) These autopsy studies have shown consistently that many individuals with amalgam have toxic levels of mercury in their brains or kidneys.(c) There is no correlation between mercury levels in blood or urine, and the levels in body tissues or the severity of clinical symptoms. SCENIHR only relied on levels in urine or blood.(d) The half-life of mercury in the brain can last from several years to decades, thus mercury accumulates over time of amalgam exposure in body tissues to toxic levels. However, SCENIHR state that the half-life of mercury in the body is only "20-90 days".(e) Mercury vapor is about ten times more toxic than lead on human neurons and with synergistic toxicity to other metals.(f) Most studies cited by SCENIHR which conclude that amalgam fillings are safe have severe methodical flaws.

Toxicology of Alkylmercury Compounds

Methylmercury is a global pollutant and potent neurotoxin whose abundance in the food chain mandates additional studies on the consequences and mechanisms of its toxicity to the central nervous system. Formulation of our new hypotheses was predicated on our appreciation for (a) the remarkable affinity of mercurials for the anionic form of sulfhydryl (-SH) groups, and (b) the essential role of thiols in protein biochemistry. The present chapter addresses pathways to human exposure of various mercury compounds, highlighting their neurotoxicity and potential involvement in neurotoxic injury and neurodegenerative changes, both in the developing and senescent brain. Mechanisms that trigger these effects are discussed in detail.

Multiple sclerosis: an update for oral health care providers

Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the central nervous system. The disease mostly affects young adults and is increasing in prevalence and incidence. Multiple sclerosis is characterized by periods of activity and remission which, after numerous relapses, cause permanent neurologic deficits. Diagnosis of MS is based on patient history and clinical examination supplemented by the findings of radiologic and laboratory tests. Numerous motor and sensory disturbances occur in MS and may present in the orofacial region. This medical management update highlights issues that are important to the oral health care provider, including orofacial manifestations of MS and dental considerations for patients with MS.

Comments on the Article “The Toxicology of Mercury and Its Chemical Compounds” by Clarkson and Magos (2006)

Clarkson and Magos (2006) provide their perspectives on the toxicology of mercury vapor and dental amalgam. As scientists who are involved in preparing a German federal guideline regarding dental amalgam, we welcome additional scientific data on this issue. However, Clarkson and Magos do not present all the relevant studies in their review. The additional data provided here show that: (a) Dental amalgam is the main source of human total mercury body burden, because individuals with amalgam have 2-12 times more mercury in their body tissues compared to individuals without amalgam; (b) there is not necessarily a correlation between mercury levels in blood, urine, or hair and in body tissues, and none of the parameters correlate with severity of symptoms; (c) the half-life of mercury deposits in brain and bone tissues could last from several years to decades, and thus mercury accumulates over time of exposure; (d) mercury, in particular mercury vapor, is known to be the most toxic nonradioactive element, and is toxic even in very low doses, and (e) some studies which conclude that amalgam fillings are safe for human beings have important methodogical flaws. Therefore, they have no value for assessing the safety of amalgam.

Dental amalgam and multiple sclerosis: a systematic review and meta-analysis

OBJECTIVES

Amalgam restorations have long been controversial due to their mercury content. Allegations that the mercury may be linked to nervous disorders such as Alzheimer's, chronic fatigue syndrome, and multiple sclerosis (MS) have fueled the calls for the removal of amalgam restorations from dentists' armamentarium. To explore and quantify the association between amalgam restorations and MS we have conducted a systematic review and meta-analysis of the literature.

METHODS

A systematic search in Medline (from 1966 to April 2006), EMBASE (2006, Week 16), and the Cochrane library (Issue 2, 2006) for English-language articles meeting specific definitions of MS and amalgam exposure was conducted. Studies were also identified using the references of retrieved articles. Studies were independently reviewed by two authors and disagreements were resolved by consensus. Studies were selected based on an a priori of defined criteria. Odds ratios (ORs) or relative risks were pooled using the random effects model. Heterogeneity was assessed using Q statistics.

RESULTS

The pooled OR for the risk of MS among amalgam users was consistent, with a slight, nonstatistically significant increase between amalgam use and risk of MS.

CONCLUSION

Future studies that take into consideration the amalgam restoration size and surface area along with the duration of exposure are needed in order to definitively rule out any link between amalgam and MS.

Verifiable CPD paper: factors that influence the dental attendance pattern and maintenance of oral health for people with multiple sclerosis

OBJECTIVE

To determine the impact of multiple sclerosis (MS) on patient attendance at dental practices and maintenance of oral health.

DESIGN

A cross-sectional postal questionnaire-based study.

SETTING

Leicestershire, United Kingdom.

SUBJECTS AND METHODS

People with MS in Leicestershire identified from local health authority records (n = 476).

MAIN OUTCOME MEASURES

Number registered at dental practice, frequency of attendance, issues and perspectives relating to attendance and maintenance of oral health.

RESULTS

A response rate of 61% (n = 289) was obtained. When compared to the general population, a higher number of people with MS were registered with a dentist (49%:88%) and displayed more frequent practice attendance (71%:81%) in the past year. People with MS reported difficulties in attending a dentist and maintaining oral health, which were exacerbated by deterioration in general health. Problems relating to reduced personal mobility had the greatest impact on attendance.

CONCLUSIONS

MS has a negative impact on perceived patient attendance and maintenance of oral health. Patients with a progressive disability could benefit greatly from the provision of preventive oral health care. The importance of seeking care earlier rather than later needs to be emphasised to both professionals and patients alike. Further efforts are required to increase awareness of the importance of oral health to the quality of life of people with MS and ensure that individuals with physical disabilities receive the same access to dental services as the able-bodied.

Mercury amalgam dental fillings: an epidemiologic assessment

Dental amalgam fillings containing approximately 50% mercury have been used for almost 200 years and have been controversial for almost the same time. Allegations of effects caused by amalgams have involved many diseases. Recent evidence that small amounts of mercury are continuously released from amalgam fillings has fuelled the controversy. This is a comprehensive review of the epidemiologic evidence for the safety of dental amalgam fillings, with an emphasis on methodological issues and identifying gaps in the literature. Studies show little evidence of effects on general chronic disease incidence or mortality. Limited evidence exists for an association with multiple sclerosis, but few studies on either Alzheimer's or Parkinson's diseases. The preponderance of evidence suggests no renal effects and that ill-defined symptom complexes, including chronic fatigue syndrome, are not caused by amalgams. There is little direct evidence that can be used to assess reproductive hazards. Overall, few relevant epidemiologic studies are available. Most prior assessments of possible amalgam health effects have been based on comparisons of dental mercury exposures with occupational exposures causing harm. However, the amalgam-exposed population contains a broader, possibly more susceptible, spectrum of people. Common limitations of population-based studies of dental amalgam effects include inadequate longitudinal exposure assessment and negative confounding by better access to dental care in higher socioeconomic groups. Better designed studies are needed, particularly for investigation of neurodegenerative diseases and effects on infants and children.

The Potential Adverse Health Effects of Dental Amalgam

There is significant public concern about the potential health effects of exposure to mercury vapour (Hg(0)) released from dental amalgam restorations. The purpose of this article is to provide information about the toxicokinetics of Hg(0), evaluate the findings from the recent scientific and medical literature, and identify research gaps that when filled may definitively support or refute the hypothesis that dental amalgam causes adverse health effects. Dental amalgam is a widely used restorative dental material that was introduced over 150 years ago. Most standard dental amalgam formulations contain approximately 50% elemental mercury. Experimental evidence consistently demonstrates that Hg(0) is released from dental amalgam restorations and is absorbed by the human body. Numerous studies report positive correlations between the number of dental amalgam restorations or surfaces and urine mercury concentrations in non-occupationally exposed individuals. Although of public concern, it is currently unclear what adverse health effects are caused by the levels of Hg(0) released from this restoration material. Historically, studies of occupationally exposed individuals have provided consistent information about the relationship between exposure to Hg(0) and adverse effects reflecting both nervous system and renal dysfunction. Workers are usually exposed to substantially higher Hg(0) levels than individuals with dental amalgam restorations and are typically exposed 8 hours per day for 20-30 years, whereas persons with dental amalgam restorations are exposed 24 hours per day over some portion of a lifetime. This review has uncovered no convincing evidence pointing to any adverse health effects that are attributable to dental amalgam restorations besides hypersensitivity in some individuals.

Why we should offer routine vitamin D supplementation in pregnancy and childhood to prevent multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that runs a chronic course and disables young people. The disease is more prevalent in the geographic areas that are farthest from the equator. No form of treatment is known to be effective in preventing MS or its disabling complications. A number of epidemiological studies have shown a protective effect of exposure to sunlight during early life and a recent longitudinal study confirmed that vitamin D supplementation reduced life-time prevalence of MS in women. Very little is known regarding the role of vitamin D on the developing brain but experimental data suggest that cerebral white matter is vitamin D responsive and oligodendrocytes in the brain and spinal cord and express vitamin D receptors. It is possible that differentiation and axonal adhesion of oligodendrocytes are influenced by vitamin D level during brain development and a relative lack of vitamin D may increase oligodendroglial apoptosis. The age effect of migration on susceptibility to develop MS could be explained by a role of vitamin D on brain development. In areas of high MS prevalence, dietary supplementation of vitamin D in early life may reduce the incidence of MS. In addition, like folic acid, vitamin D supplementation should also be routinely recommended in pregnancy. Prevention of MS by modifying an important environmental factor (sunlight exposure and vitamin D level) offers a practical and cost-effective way to reduce the burden of the disease in the future generations.

Bias in dental research can lead to inappropriate treatment selection

The first RCT was instituted in the early 1950s, evaluating streptomycin and bed rest compared with bed rest alone for tuberculosis. This research design has become the reference standard for comparative evaluations of therapies because of its prospective nature and the ability to control bias. Because it is easier to conduct observational studies, they have often been inappropriately substituted for the better experimental study designs. Since the 1950s, however, readers of the medical literature have slowly come to demand quality clinical research to assist them in caring for their patients. Dentists are somewhat behind their medical colleagues in using the strongest research designs to answer clinical questions. In dentistry, observational studies with convenience samples of patients have been commonly used. It is often argued that few dental ailments affect a person's life as negatively as most medical maladies; therefore, experimental rigors are not required of dental research. Although most dental care does not involve life-and-death issues, dentists are as eager as physicians to offer their patients optimal care. Optimal care is best defined through nonbiased research strategies.