Biology of amalgam fillingsThe amalgam controversyThe opposing sidesThe toxicology of mercury (26)Diagnostic criteriaClaims of “amalgam illness”Standards of evidenceOther claimsSlide 9Hg release from amalgamHg levels and symptomsSymptoms and special casesSymptoms and SiblerudThe evidence from EuropeStudies of “amalgam illness”Amalgam and neurotoxicityAmalgam and Alzheimer'sAmalgam and chronic diseaseSlide 19Amalgam and immunityAmalgam and allergyContact hypersensitivityGenetic Hg sensitivity - miceHuman genetic Hg sensitivity?Slide 25Other metals in amalgamMy conclusions - safetyMy conclusions - removalThe ADA code of ethicsBiology of amalgam fillingsDENT 5301Introduction to Oral Biology© Dr. Joel RudneyThis material may not be reproduced in any form, without permission from the copyright holder.The amalgam controversyWhat is amalgam?Alloy of Hg (50%), silver (35%), tin (13%), copper, zincHistorically the most widely used dental materialDesirable properties of malleability and durabilityStill a popular choice for restoring cariesGold; composite resins are other optionsThe question of mercuryHg (and other metals) are toxic in high dosesAmalgam releases very low levels of Hg vaporIs this exposure to Hg sufficient to cause adverse effects?The opposing sidesThe ADA/NIH positionAmalgam has been used for over a centuryMinimal evidence of harmful effects with proper useIt is inappropriate to:Encourage patients to have amalgams removed (costly)Promote amalgam removal as a cure for any diseaseRemove healthy tooth structure just to remove amalgamThe anti-amalgam positionPrevalent among the alternative medicine communityClaim any exposure to Hg is toxic in susceptible peopleClaim amalgams are responsible for many diseasesClaim amalgam removal/Hg chelation can cure diseases e.g.Chronic fatigue, MS, Alzheimer's, auto-immune diseasesThe toxicology of mercury (26) Cases of overt Hg toxicity (CNS effects)Environmental releases (pesticides, pollution, seafood)Occupational exposures"Mad hatters"Thermometer factoriesChemical industries (chloralkali workers)Dental personnel (safety procedures, level of exposure)Symptoms are dose-dependent; increase with exposureTremor; impaired motor skillsMood disturbances (irritability, behavior changes)Memory problemsFatigue; weaknessGastrointestinal disturbances; kidney problemsDiagnostic criteriaBecause symptoms are so vague, diagnosis based on:Documented source of exposureOutside population norms on standardized testsMood scales, motor skills, cognitive function, etc.Elevated Hg in urine, blood etc.WHO threshold level above which subtle effects occurUrinary level of 35 µg Hg/g creatinine (26)Persons with amalgams and no other Hg exposureUrinary Hg averages about 10-fold lower than threshold (26)Claims of “amalgam illness”Popularized by media in Scandinavia and GermanyHas led to proposals that amalgam be bannedSwedish Assn. of Patients Damaged by Dental TreatmentSymptoms they consider to be signs of amalgam illness:Muscle and joint pain, tiredness, vertigo, headache, G.I.disorders, dry eyes, other eye problems, smarting/ulceration in mouth, heart trouble, circ. disorders/coldhands & feet, memory loss, difficulty breathing, earsstopped up, depression, difficulty concentrating, rash, eczema, itching, throat trouble, restlessness, anxiety,nervousness, trembling, twitches, cramps, nausea,vomiting, prickling/creeping sensation, tension,tremor, heat sensation, sinusitis, hair loss (24)Standards of evidenceSimilar broad symptoms claimed for:Chronic fatigue syndromeMultiple chemical sensitivity syndrome (28)Evidence is anecdotal, based on case reportsPatients claimed to improve after:Amalgam removalChelation therapy (used for overt Hg poisoning)This standard of evidence fails to exclude:Placebo effectSpontaneous remissionOther claimsAmalgam also has been claimed to cause:Alzheimer's diseaseMultiple sclerosisKidney damageDevelopment of antibiotic resistant oral/fecal bacteriaCardiovascular diseaseMale infertilitySmokingImmune system dysfunctionT-cell abnormalitiesAuto-immune diseasesAllergySome suggest treatment by amalgam removal/chelationStandards of evidenceSome claims are anecdotal; others based on limited studiesNo controls or inappropriate controlsAnti-amalgam authors (25, 37-45, U2, U5, U9, U11-12, U16 )M. J. Vimy, F. L. Lorscheider, R. L. Siblerud (25, 37-45)International Academy of Oral Medicine and ToxicologyOthers have been unable to replicate their findingsSome articles distort or misrepresent contrary findings“The study cited by Gotwald et al. as proof of there being no connection between Hg and Alzheimer’s disease (Saxe et al., 1999) was published in a dental association trade journal, which is not a peer-reviewed scientific journal” (U12)This statement refers to JADAAll scientific articles published in JADA are peer-reviewedHg release from amalgamLow levels of Hg vapor released from amalgam (26)Mostly excreted in urine, but some stays in tissuesHg higher in persons with amalgamsHg in body fluids correlated with # of amalgamsAre levels of exposure unacceptably high?Depends on calculation methodsAmalgam opponents criticized for method errors (26)Not adjusting Hg vapor meter for lung volumeTheir estimates too high vs. brain uptake data•16 µg/day vs. 2 µg/day for avg. 12.6 fillingsHg levels and symptomsAre Hg levels higher in "amalgam illness" patients?10 self-diagnosed patients compared to 8 controls (4)Amalgam levels the sameHg vapor every 30-40 min for 13.25 h; blood, urineNo difference in uptake (2 µg/day)Urine Hg lower in Pts., 10-fold lower than thresholdNo Hg differences in 50 pts. and 50 controls (7)No Hg differences in 99 pts. and 272 controls (28)Symptoms and special casesFew case reports of high Hg linked to excessive gum, bruxersLevels much higher than self-diagnosed patients (3, 23)Dentists working with amalgam (9, 22, U13)No Hg toxicity in Swedish dentists w/proper handlingVery subtle "preclinical effects" in US, British dentistsTest results within norms, but correlated with Hg levelsNo control for amalgam handling proceduresSymptoms and SiblerudLimited by cross-sectional design, self-referred