Amalgam safety & mercury hazards 3rd year 1 2012


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Amalgam safety & mercury hazards 3rd year 1 2012

  1. 1. Amalgam Safety & Mercury Hazards (1-2010) BY: Prof. Mostafa Abdulhamid HassanMercury One of the few metals that is liquid at room temperature Used in medicinal preparations for more than 2000 years Diuretics, laxatives, skin preparations Used in over 60 industrial applications: Chlorine production, insecticides, neon lights, paint, etc.Mercury Uses Thermometers Electric Switches Fluorescent Lamps Batteries Insecticides Rat poisons Disinfectants Dental AmalgamPhysical Properties of Mercury : Melting Point -38°C Boiling Point 356°C Density 13.5 gm/ml Low heat of vaporization allows oxide-free metallic Hg to evaporate easily at room temperatureForms of Mercury Metallic - Hg - Stable/Unreactive Ionic - Hg+ - Reactive/Not a HazMat Salts - HgCl - Mercuric Chloride Compounds - Amalgam Methyl Hg - Reacted Toxic Form/Poison Vapor - Detectable? 1
  2. 2. Mercury is present in the environment and it is taken into the body inone form or another via water, air and food on daily basisScientific Facts High levels of Hg do produce toxic effects Hg vapor is minute/undetectable Blood Hg increases upon removal of amalgam Dental personnel have greatest exposure without evidence of decreased health True hypersensitivity to amalgam = allergic reactions or lichenoid lesionsSources of Mercury Exposure in Dental Office Amalgam raw materials stored for use. Mixed, unhardened amalgam during trituration and insertion. Amalgam scrap Amalgam undergoing F & P Amalgam being removed Mercury leakage of amalgam capsulesN.B : Once the amalgamation reaction is completed , only extremelyminute levels of mercury can be released and those are far below thecurrent health standard .Historical IssuesFirst Amalgam War 1985 Huggins DDS “It’s All In Your Head”1990 60 minutes Program “Poison In Your Mouth”Anti-amalgamistsThe Hazards From Mercury in Dentistry is Mainly Three Folded : 1. Systemic absorption of mercury through direct contact wit skin 2. Inhalation of mercury vapor given off at room temperature 2
  3. 3. 3. Inhalation of air borne particles of mercury contaminated particlesAnti-amalgam Claims  Neurotoxicity  Renal Dysfunction  Birth Defects  Arthritis  Multiple Sclerosis  Chronic Fatigue  Etc , Etc , Etc…Others Add Too !!  Candida Infection  Hodgkin’s Disease  Mononucleosis  Depression  Ulcers  Epilepsy  Etc, Etc, Etc...Adverse Reaction to Mercury Toxicity Sensitization (hypersensitivity) Mercurialism (Symptoms)Symptoms of Mercury Toxicity Insomnia Physical weakness Irritability Loss of memory Impaired vision Nervous excitability Headaches Depression Speech disorders 3
  4. 4. Muscular tremorsThreshold Limit Value ( TLV ) for Mercury Vapor is 0.05 mg (50 µg/m3)This concentration of mercury vapor represents the maximum level ofmercury vapor in which a person can work for 40 h/week withoutdemonstrable health risks.Mercury ToxicityGood NewsAlthough the hazard is present, there have been --NO REPORTS OFMERCURY VAPOR TOXICITY IN DENTAL OPERATORIESFactors Affecting Mercury Leakage of Amalgam Capsules 1. Type of capsule ( single use or reusable capsule ) 2. Mixing time (especially with high speed amalgamator) 3. Mixing speed 4. Temperature 5. Presence of pistonJorgensen Method of Checking Leaky Amalgam CapsuleWinding adhesive plaster around Capsule --- trituration ---inspection of the sticky surface of the plaster for mercury dropletsMethods of Detection of Mercury Vapor at Dental Operatory 1. Direct reading portable instrumentation (portable mercury spectrometer) 2. Mercury absorption procedures: collecting systems --- analytical lab. 3. Mercury dosimeter Materials : a. cadium sulphide b. palladium chloride c. gold filmThe generally accepted Threshold Limit Value (TLV) for exposure tomercury vapor for a 40-hour work weekly is 50 µg/m3 4
  5. 5. Evaluation of Mercury Exposure Levels In the working environment 50 µg/m3 In biological fluids Urine : 150 µg/L Saliva : 150 µg/100 mL Blood : 0.1 mg/100 mL Hair and Nails : 7 ppm Amalgam waste management Mercury-free direct metallic restorations Amalgam replacement ( Ethical & Scientific issues) Shouldn’t I ? Many people want to replace their silver fillings because they have heard that there is medical risk from the mercury in the silver fillings. There are no clinical studies to prove that there is any risk in having a silver filling, so this should not be a reason for there replacement. Literature available upon requestEthics Unless new and compelling evidence is presented to the contrary, dentists cannot ethically tell patients that dental amalgam is a health hazard or that removal of amalgam restorations will benefit their health. When clinical research demonstrates that tooth-colored restoratives are as economical and effective in the long-term as dental amalgam, switch. 5
  6. 6. Dental Mercury Hygiene Recommendations (ADA) Store in an unbreakable tightly sealed containers Use non-touch technique for amalgam handling Work in well-ventilated spaces Avoid carpeting dental operatories (decontamination is not possible) Avoid heating mercury or amalgam Use water spray and suction when grinding amalgam Do not use ultrasonic amalgam condensers Perform yearly mercury determination on all personnel regularly employed in dental offices Have periodic mercury vapor level determination in operatories Alert all dental personnel with the potential hazards of mercury during handling dental amalgam Clean up any spilled mercury immediately Use tightly closed capsules during amalgamation Perform all operation involving mercury over areas that have impervious and lipped surfaces Eliminate the use of mercury containing solutions Use an amalgamator with completely closed arm If possible, recap single use capsules after use and properly dispose them Remove professional clothing before leaving the work placeConclusions Continue to use amalgam unless esthetics is a concern Use conservative preparations Use resin sealants for non-carious fissures Monitor research on bonded amalgams Practice safe mercury hygiene Stay informed!Amalgam Restrictions None in the United States 6
  7. 7. Sweden, Denmark, and Germany have proposed restrictions on amalgam use The intent is to reduce the environmental release of Hg , it is not due to amalgam restoration danger. Environmental concerns may limit our usage, not the “mercury poisoning” of our patients. Again Judgment 4 U “ Now R U Trusted In ………..!!!Suggested Readings , Art & science of Operative Dentistry, Fourth Edition 2002, Pages 158-168. 7