Amalagam Safety Flashcards
what is amalgam
- a mixture or blend
- an alloy of mercury with another metal
- silver, tin, copper and mercury
how much mercury is in current dental amalgam alloys
- spherical: 42%
- mixed: 47-50%
what are the forms of mercury
- organic: methyl Hg
- elemental: Hg0
- inorganic Hg salts: Hg+1 or Hg+2
describe organic mercury- methyl Hg
- most toxic form
- fungicides, fish, water
- when taken up by fish, bioaccumulates up the food web
- 95% GI absorption
- lipid soluble, uniform distribution throughout body tissues
- toxicity: neurological damage
- most large scale poisonings
describe elemental Hg0
- liquid metal
- vaporizes easily, passes through membranes, skin and blood brain barrier
- little or no oral or GI absorption
- lungs absorb vapor
- can have toxic CNS effects with breathing lots of vapor
- occurs through inhalation in occupational setting or mercury spills in poorly ventilated area
- used in dentisrty
describe inorganic mercury
- compounds used extensively in industry
- mercuric chloride, bromide, sulfate, nitrate
- least toxic form
- GI absorption poor
- mercuric ions concentrate in kidneys, acute toxicity renal necrosis
- water soluble, environment water pollution
what are the acute effects of elemental Hg vapor
- chills, cough
- metallic taste
- weak, dizzy
what are the chronic effects of elemental Hg vapor
- tachycardia
- tremor, confusion
- depression
- excess salivation
- “mad hatter”
what are the effects of organic Hg
- dizziness
- speech problems
- visual disturbances
- tingling, numbness
- weakness
- hearing loss
- confusion, memory loss
- renal failure
- fetal effects
what are the sources of mercury
- food: inorganic and methyl Hg
- water: inorganic Hg
- air: Hg vapor elemental
what are the food sources of mercury
- non-fish, inorganic Hg
- seafood, methyl Hg
- dont eat shark or swordfish
- 12 oz (2 meals) /week of lower Hg fish such as shrimp, light tuna, slamon, pollock, catfish,
- albcaore tuna- higher Hg than light tuna (6oz/week)
where is Hg in water
- electronic manufacturing plants
- air emissions recycle into water
- dental office waste water
where is Hg in air
- power plant emissions
- municipal combustors
- medical waste incinerators
- dental amalgams, Hg vapor = elemental mercury
what is the daily mercury exposure
- food: 15 micrograms
- air: 1 microgram
- water 0.4 micrograms
- amalgam vapor: 1-4 micrograms
what is the allowable Hg in industry workers
350-500 micrograms
- 40 hour work week
do dental workers have a higher incidence of mercury related illness
no
is mercury an allergy
rare- less than 1% of population
what are the mercury toxicity claims in dentistry
- Hg migrates through tooth roots into bone and gingiva
- IQ and brain Hg level proprotional to number of fillings
- amalgams cause 50% reduction in kidney function
- Hg causes immune disorders such as arthritis, lupus, lichen planus, chron’s disease, alzheimers diease, amyotrophic lateral sclerosis, multiple sclerosis
what is micromercurialism
vague diffuse symptoms
no _____ Hg in dental amalgam
methyl
describe elemental Hg0 vs chemically bound Hg
- in final restoration Hg chemically bound to Ag
- elemental H and O versus H2O
- elemental Na and Cl vs NaCl
how is mercury vapor produced in dentistry
- mixing, insertion, polishing and removal
- mastication
mercury levels are best measured through:
urine
describe bisphosphenol A release
- BPA estrogenicity
- association diabetes and cardiovascular disease
- concerns composites and sealants
what are the mercury levels in blood in patients with and without amalgam restorations
- with: 0.6-0.7 mg/L
- without 0.3-0.8 mg/L
what are the urine levels of Hg in patients with amalgam, dental personnel, and one seafood meal
- patients with amalgam: less than 5microg/L
- dental personnel: less than 10microg/L
- one seafood meal: 5-20 microg/L
what is the normal blood and urine Hg levels
- blood: 0-10 microg/L
- urine: 0-25 microg/L
when is Hg vapor highest
at insertion or removal
what risk is amaglam classified as
class II moderate risk - same classification as composites or other dental alloys
what percentage of restorations currently placed are amalgams
30%
what would be the economic impact of banning amalgam
- increased cost of alternative restorations
- increased untreated disease for under and uninsured
what is the maximum safe exposure level in the air
50 micrograms per cubic meter
what are the mercury hygiene recommendations
- avoid direct contact
- clean up spills immediately
- well ventilated office
- no ultrasonic amalgamators
- use amalgamator lid
- high volume evacuation and water spray
- monitor Hg levels in office
- avoid carpeted operatories
- dont heat, incinerate or sterilize amalgam
- scrap amalgam, store in air tight container and then recycle
why use high volume evac and water spray
- 6 fold decrease in Hg vapor
- decreased heat from cutting
- rubber dam decreases patient exposure
what is the overall enivronmental mercury release
- 53% fuel combustion
- 34% waste combustion
- 13% manufacturers and consumers
- less than 1% from dentistry
how should amalgam waste be handled
- amalgam capture device
- contact amalgam has contacted pt
- non contact amalgam leftover mix
- amalgam sludge
- empty amalgam capsules
where is the amalgam capture devide
- chair side trap
- vacuum pump filter
- amalgam separator
what does the chairside trap do
collects amalgam particles from evacuation line
what does the vacuum filter do
upstream from central vacuum pump to remove amalgam from suctioned water
what does the amalgam separator do
- collects amalgam prior to central vacuum pump
- sedimentation/filtration/ion exchange
- without separator up to 80% is captured at the office and up to remaining 20% at the waste water treatment plants
- EPA mandated in 2017
need _____ chairside amalgam separators
multiple
filters/collection for chairside amalgam separators need sent off:
annually
what is the problem and advantage of central amalgam separator
- problem: prophy paste cause system clogs
- advantage: only one filter to replace
