This document discusses mercury use in dentistry and its risks. It covers the history of dental amalgam, forms of mercury exposure including vapor release from dental fillings, and health effects like neurological and renal toxicity. Regulations for mercury in dentistry are outlined, such as the OSHA exposure limit. The document also describes managing mercury spills and proper disposal of dental waste containing mercury.

2. CONTENTS
• Introduction
• History of mercury in Dentistry
• Overview of Dental Amalgam
• Hazards of Mercury
• Forms of Mercury
• Mercury in Dentistry
• Sources of Exposure
• Pharmacokinetics of Mercury Exposure
• Regulation and Guidelines
• Management of Mercury Toxicity
• Alternatives to Dental Amalgam
• Conclusion
• References

3. INTRODUCTION
Hydrargyrum
Still used widely in
developing countries Highly Toxic Less Technique
Sensitive
Durable Disposal Risks

4. HISTORY OF MERCURY USE IN DENTISTRY
Hyson Jr JM. Amalgam: Its history and perils. Journal of the California Dental Association. 2006 Mar 1;34(3):215-29.

5. AMALGAM WAR
1920 (First Amalgam
war)
1980 (Dr Hal Huggins) 1991
V/s
1926 (Alfred Stock)
Mentioned his
own accounts
of mercury
poisoning
Argued with
GV Black
Dodes JE. The amalgam controversy: an evidence-based analysis. The Journal of the American Dental Association. 2001 Mar 1;132(3):348-56.
Second amalgam war Third amalgam war

6. OVERVIEW OF DENTALAMALGAM
The most widely used restorative material Can last up-to 10 years 50% Failure: Faulty
Restoration
Composition
ADA Specification No. 1
Manufacturing
Melting Homogenization
Particle Formation Cooling and Equilibrium
Ball Milling
Thermodynamic
Equilibrium
150 – 400 ‘C
Mackenzie, L. (2021). Dental amalgam: a practical guide. Dental Update. https://doi.org/10.12968/denu.2021.48.8.607.

7. OVERVIEW OF DENTALAMALGAM
PRIMARY PHASES
Gamma (Ag3Sn) Gamma 1 (Ag2Hg3) Gamma 2 (Sn7-8Hg)
Silver – Tin alloy powder
before its mixed with Hg
When Hg mixed with
Silver-Tin alloy
Silver reacts with Hg to
form Ag2Hg2
(Gamma 1 Phase)
- DURABLE
- MAKES AMALGAM
USEFUL
Weak phase formed when
Hg reacts with Tin
(Sn8Hg)
Most prone to corrosion
and creep
Less Corrosion
Resistant
Vimal K Sikri: Textbook of Conservative and Restorative Dentistry. 1st Edition. 2019

8. ADVANTAGES OF AMALGAM
Antony K, Genser D, Hiebinger C, Windisch F. Longevity of dental amalgam in comparison to composite materials. GMS health technology assessment. 2008;4.
Durable Less Technique
Sensitive
Minimal
Placement Time
Can be used in
many clinical
situations
Corrosion
products provide
marginal seal
Less Expensive & Economical
Excellent
Compressive
strength
Proper Isolation
not necessary
Can be repaired easily

9. ROLE OF MERCURY IN AMALGAM
ACTS AS A BINDING AGENT
MERCURY RELEASES VAPOURS
RISK FOR PATIENT AND OPERATORS
Vimal K Sikri: Textbook of Conservative and Restorative Dentistry. 1st Edition. 2019

10. DOUBLE AND TRIPLE DISTILLED MERCURY
Mercury contains impurities which might interfere with dental amalgam
Fractional Distillation Boiling the mixture Collecting vapours as they condense
Less interference with
properties
More interference with
properties
Hulett GA, Minchin HD. The Distillation of Amalgams and the Purification of Mercury. Physical Review (Series I). 1905 Dec 1;21(6):388.

11. PREGNANCY & MERCURY
Dental amalgam releases mercury vapors which can be particularly harmful for the fetus
as it’s organs are not fully developed
Low Birth Weight Small Head Circumference Delayed Development
Hearing & Vision problems Neurodevelopmental Disorders
American Dental
Association
European Union US Environment
Protection Agency
World Health
Organisation
Golding J, Steer CD, Gregory S, Lowery T, Hibbeln JR, Taylor CM. Dental associations with blood mercury in pregnant women. Community dentistry and oral epidemiology. 2016 Jun;44(3):216-22.

12. HAZARDS OF MERCURY
Mercury is a heavy metal
Not Absorbed
Methylmercury disrupts essential biochemical
processes by binding to enzymes & proteins

13. FORMS OF MERCURY
Elemental Mercury
Odourless / Shiny liquid
Vaporizes at room
temperature
Used in thermometers / amalgam /
fluorescent light bulbs
Ethyl Alcohol promotes
rapid excretion of
mercury
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

14. FORMS OF MERCURY
Inorganic Compounds
Found in batteries & skin creams
Not readily
absorbed
Can be toxic if
inhaled or ingested
MERCURY SALTS
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

15. FORMS OF MERCURY
Organic Compounds
Methylmercury
Organomercurials
Bioaccumulation
and bio-
magnification
Can cross blood
brain barrier and
placenta
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

16. MERCURY IN DENTISTRY
What forms of mercury do we, as Dentists, encounter in daily clinical
practice?
Elemental Mercury Methyl Mercury
Mercury Vapour
Studies have suggested that dentists could
experience adverse effects from air
concentrations of mercury as low as 14
micrograms per cubic meter, which is much
lower than the limit of 50 micrograms per
cubic meter.
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. J Dent Res. 2006;85(1):1-19. doi:10.1177/0022034505283256

17. MERCURY IN DENTISTRY
Leaching from amalgam restoration is minimal. Estimates are that
450-530 amalgam surfaces would be necessary to expose an
individual to minimal toxic effect of mercury. (32 teeth 160 surfaces)
Mackert Jr JR, Berglund A. Mercury exposure from dental amalgam fillings: absorbed dose and the potential for adverse health effects. Critical Reviews in Oral Biology & Medicine. 1997 Oct;8(4):410-36.

18. SOURCES OF EXPOSURE
Improper disposal of mercury
from dental amalgam scraps
Ingestion of contaminated fish
Hg bonded to organic compounds
Most human exposure to metallic mercury comes from mercury vapor
outgassing from amalgam fillings, at a rate of 2 to 28 micrograms per
facet surface per day, with about 80% being absorbed.
Occupational exposure
- Dental Clinics / Production of
thermometers, barometers and
fluorescent lamps / gold mining /
coal fired power plants
Volcanic Eruptions
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. J Dent Res. 2006;85(1):1-19. doi:10.1177/0022034505283256

19. SOURCES OF EXPOSURE
Mercury Spills
Expression of excess Hg
from Amalgam
Leakage from dispensers
Improper Storage
of scrap Amalgam
Leakage from capsule
while trituration
Langan DC, Fan PL, Hoos AA. The use of mercury in dentistry: a critical review of the recent literature. The Journal of the American Dental Association. 1987 Dec 1;115(6):867-80.

20. SOURCES OF EXPOSURE
Other
Sources
mercury vaporization from contaminated instruments placed in sterilizers
grinding of amalgam during removal of restorations
amalgam condensation with ultrasonic condensers
Studies have found little or no difference in ambient air
concentrations of mercury vapor between offices with carpeting
and those with hard floor coverings
Langan DC, Fan PL, Hoos AA. The use of mercury in dentistry: a critical review of the recent literature. The Journal of the American Dental Association. 1987 Dec 1;115(6):867-80.
V/s

21. PHARMACOKINETICS OF MERCURY EXPOSURE
INORGANIC
MERCURY
Elemental / Metallic Mercury
80% 19% 1%
> >
Mercury Vapour Sulphur containing amino acids
Metallic Mercury
Blood Brain
Barrier
Placenta
Foetal
Brain
Influences T-Cell
function
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

22. PHARMACOKINETICS OF MERCURY EXPOSURE
INORGANIC
MERCURY
Elemental / Metallic Mercury
Metallic Mercury Mercuric Mercury
excretion
Excretory Half
Life
Depends on
Organ
Redox
State
CNS – Hg has several years of half life
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

23. PHARMACOKINETICS OF MERCURY EXPOSURE
INORGANIC
MERCURY
Mercurous Mercury / Calomel
Poorly soluble / not readily absorbed
Metallic Hg Mercuric Hg
Pink disease &
Acrodynia
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

24. PHARMACOKINETICS OF MERCURY EXPOSURE
INORGANIC
MERCURY
Mercuric Mercury
Photographic film
development
Skin Lightening cream
Only 2% absorbed – rest
corrodes the intestine
HgCl2 Sulfhydryl groups on
erythrocytes
Metallothionein Glutathione
Mercuric Mercury Proximal Convoluted Renal Tubule
Half Life 42 days for 80%
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

25. PHARMACOKINETICS OF MERCURY EXPOSURE
ORGANIC MERCURY
Methyl Mercury
Major form of
organic mercury
Relatively Stable
80%
Sulfhydryl groups in cysteine
Methyl Mercury
Inorganic
Mercury
(
DEMETHYLATION
)
Half Life 70 Days ( 90% excretion in stool )
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

26. SYMPTOMS OF TOXICITY
INORGANIC
MERCURY
Metallic Mercury Vapour
Alters tertiary and
quaternary structure of
proteins
Binds with sulfhydryl and
selenohydryl groups
ACUTE CHRONIC
Erosive bronchitis
Bronchiolitis
Low Level Exposure
High Level Exposure
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.

27. SYMPTOMS OF TOXICITY
INORGANIC
MERCURY
Mercuric Mercury ACUTE CHRONIC
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.
extensive precipitation of enterocyte
intestinal cell proteins
Abdominal pain / vomiting / bloody
diarrhea
Renal tubular necrosis
Autoimmune
glomerulonephritis
Thyroid Dysfunction
Decreased
Spermatogenesis

28. SYMPTOMS OF TOXICITY
ORGANIC MERCURY
Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.
Renal tubular necrosis
Autoimmune
glomerulonephritis
Thyroid Dysfunction
Methyl & Ethyl Mercury Pre Natal Exposure Post Natal Exposure
Massive Exposures
Cerebral Palsy
Lesser Exposures
Neurodevelopmental Delays
Lesser Exposures
Paraesthesia
Moderate Exposures
Ataxia / Visual-Auditory-
Extrapyramidal impairments
Severe Exposures
Clonic Seizures

29. ACRODYNIA
Pinks Disease
Due to mercury poisoning
ACRO + DYNIA
(extremity) (pain)
• SYMPTOM
S
Peripheral
Neuropathy
Pain / Paraesthesia / Itching / Burning
Physical
Symptoms
Discolouration / Oedema / Desquamation
Blocks
Catecholamine's
Excessive Sweating & Salivation
Rapid heart rate
Pink discolouration

30. ACRODYNIA
Pinks Disease
Due to mercury poisoning
ACRO + DYNIA
(extremity) (pain)
• SYMPTOMS IN
CHILDREN
Red Cheeks
Transient
Rashes
Red Lips
Loss of Hair / Teeth /
Nails

31. ACRODYNIA
• TREATMENT
MAIN GOAL Remove Mercury from the body
Fixing any electrolyte loss and nutritional imbalances
Chelating Agent
2,3-dimercaptosuccinic acid
(DMSA)
Hemodialysis
Patients with Acute Kidney
Injury from Mercury Toxicity
L - Cysteine added to clear out mercury from blood

32. REGULATIONS AND GUIDELINES
Estd. In 1971, is a U.S. Federal Agency under the Dept. of Labor
Ensures safe and healthful working conditions for employees
by setting and enforcing safety standards
OSHA has established Permissible Exposure Limits (PELs) for
mercury
The current limit for mercury vapor established by OSHA is 50 mg/m3
(time-weighted average) in any 8-hour work shift over a 40-hour work
week.
https://ohsonline.com/Articles/2003/07/Mercury

33. REGULATIONS AND GUIDELINES

34. REGULATIONS AND GUIDELINES
Staff handling mercury should be trained in
management and hygiene protocols.
The dental operatory should have good ventilation
and fresh air circulation.
The design of the operatory should allow easy cleanup after mercury spillage.
All clinic personnel should be aware of potential mercury contamination sources.
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

35. REGULATIONS AND GUIDELINES
Preferably, use pre-capsulated alloys; avoid using
bulk alloy and mercury
Handle amalgam carefully, avoid skin contact,
and re-cap single-use capsules
Use high vacuum evacuators during the finishing and polishing of amalgam
restorations
Store scrap amalgam and excess mercury in an air-tight container with radiographic
fixer solution FIXE
R
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

36. REGULATIONS AND GUIDELINES
Scrap and waste amalgam should be recycled
whenever possible.
Dispose of all mercury wastes and unused scrap
amalgam according to waste disposal laws.
Remove professional clothing before leaving the workplace.
Periodically monitor mercury vapor in the operatory atmosphere
using dosimeters or mercury vapor analyzers
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

37. MANAGING A MERCURY SPILL
Determine the
extent of the spill
Block foot traffic for a 2
meter radius around the spill
Ventilate the area
https://ohsonline.com/Articles/2003/07/Mercury-Spill-Control--Cleanup.aspx?Page=1

38. MANAGING A MERCURY SPILL
Wearing protective
gloves and mask
Use a mercury spill
kit to clean the spill
Join small droplets of mercury
into a large mercury pool using
a plastic or wooden spatula
https://ohsonline.com/Articles/2003/07/Mercury-Spill-Control--Cleanup.aspx?Page=1

39. MANAGING A MERCURY SPILL
The pool is then
aspirated through
a syringe
Placed in a specially
designed container
Or if that’s unavailable, in a jar
of water before sealing it off
https://ohsonline.com/Articles/2003/07/Mercury-Spill-Control--Cleanup.aspx?Page=1

40. MANAGING A MERCURY SPILL
Mix equal parts of Sulphur and
Calcium Hydroxide powder
over the spilt mercury
Area is wiped with a
damp cloth
Dispose the cloth in a sealed
polythene bag
https://ohsonline.com/Articles/2003/07/Mercury-Spill-Control--Cleanup.aspx?Page=1

41. HOW MUCH DOES A MERCURY SPILL KIT COST?
2100 /-
(PSI)
5000/-
(U-Safe)
8200/-
(Mercury Eater)

42. MANAGING OF MERCURY VAPOR RELEASE IN DENTAL CLINIC
DURING INSERTION OF
AMALGAM
Due to high vapor pressure of mercury, surrounding air
immediately gets contaminated
Once restoration is done, immediately ventilate the room
Mercury can be recycled, gauze can be placed in non
incinerated solid waste
Amalgam hardens after insertion, less mercury vapor
Amalgam scraps to be stored in the x-ray fixer solution in
a tightly capped container
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

43. MANAGING OF MERCURY VAPOR RELEASE IN DENTAL CLINIC
DURING FINISHING & POLISHING OF
AMALGAM
Finishing and polishing generates heat
Liquefies silver mercury (Ag2Hg3)
Process creates a Mercury rich phase
that smears over the amalgam surface
Slow polishing and water coolant helps
(melting point 127’C)
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

44. MANAGING OF MERCURY VAPOR RELEASE IN DENTAL CLINIC
DURING REMOVAL OF AMALGAM
Removal generates heat
Liquefies silver mercury (Ag2Hg3)
This is accelerated by the heat generated by burs
Water Coolant & High Vacuum Suction
(melting point 127’C)
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

45. MANAGING OF MERCURY VAPOR RELEASE IN DENTAL CLINIC
DURING INSTRUMENT STERILIZATION
Prior to sterilization Instruments used should be cleaned
Contaminated instruments releases mercury
on sterilization (liquid or vapor form)
Adequate Ventilation
Mahalakshmi, M. (2022). Dental materials. New Delhi, India: Jaypee Brothers Medical Publishers.

46. AMALGAM SEPARATORS
A unit installed in the dental chair apparatus to filter out
amalgam scraps and particles from wastewater
Sedimentation Filtration Centrifuge
https://www.benco.com/benco-dental-u/article/why-you-need-amalgam-separators-in-your-clinic
Khangura SD, Seal K, Esfandiari S, Quiñonez C, Mierzwinski-Urban M, Mulla SM, Laplante S, Tsoi B, Godfrey C, Weeks L, Helis E. Economic Evaluation. InComposite Resin Versus
Amalgam for Dental Restorations: A Health Technology Assessment [Internet] 2018 Mar. Canadian Agency for Drugs and Technologies in Health.
COST 200,000 Rupees or 2500$

47. MINAMATA BAY DISASTER
Industrial Disaster occurred in Japan from 1930’s to
1960’s
Industrial wastewater from the Chisso Corporation's chemical
factory, which contained methylmercury, was discharged into
Minamata Bay.
The methylmercury bioaccumulated in fish and shellfish in the
bay, a major food source for the local population.
Minamata Bay
Chisso Factory
ttps://www.med.or.jp/english/pdf/2006_03/112_118.pdf

48. MINAMATA BAY DISASTER
Minamata Disease
Protestors at the gate of
Chisso Factory
Over 2,000 people suffered from severe mercury
poisoning, known as Minamata disease.
neurological symptoms like muscle weakness, numbness in
the limbs, damage to hearing and speech
severe cases, paralysis and death.
ttps://www.med.or.jp/english/pdf/2006_03/112_118.pdf

49. MINAMATA BAY CONVENTION
January 19, 2013 – 140 countries signed up for safe use,
disposal, alternatives to mercury
Named after Minamata Bay, where the industrial
disaster took place
Primary mining, to safe storage, to the reduction of
mercury in products and industrial processes.
Specifically mentions the phase-down of dental amalgam, recognizing the need for a gradual
reduction in its use due to the challenges in immediately replacing it with alternatives.
The convention encourages member countries to promote the use of cost-effective
and environmentally sound alternatives to mercury-containing products.
https://mercuryconvention.org/sites/default/files/2021-06/Minamata-Convention-booklet-Sep2019-EN.pdf

50. https://mercuryconvention.org/sites/
default/files/2021-06/Minamata-
Convention-booklet-Sep2019-EN.pdf
Reference :

51. ALTERNATIVES TO MERCURY
Gallium and Indium were used as alternatives to mercury in
dental amalgam
Gallium is slightly toxic after 8 hours of placement into the
cavity
Gallium Poisoning: patient progressed to dangerous episodes of
tachycardia, tremors, dyspnea, vertigo, and unexpected black-outs
Wataha JC, Nakajima H, Hanks CT, Okabe T. Correlation of cytotoxicity with elemental release from mercury-and gallium-based dental alloys in vitro. Dental Materials. 1994 Sep 1;10(5):298-303.

52. Conclusion
Amalgam is a valuable restorative material, but its use is associated
with mercury toxicity. Safer alternatives and effective waste management
practices are essential to mitigate risks. The decision of whether or not to
use amalgam fillings is a complex one that should be made on a case-by-
case basis, weighing the risks and benefits carefully.
In conclusion, amalgam is a valuable material with both risks and
benefits. The best decision for each individual patient will depend on
their specific needs and circumstances.

53. References
- Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.
- Garg N Garg AAbu Tahun I. Textbook of Operative Dentistry. 3E édition ed.; 2015.
- Roberson TM Heymann H Swift EJ Sturdevant CM. Sturdevant's Art and Science of Operative Dentistry. 5th ed. St. Louis Mo: Mosby; 2006
- Vimal K Sikri: Textbook of Conservative and Restorative Dentistry. 1st Edition. 2019
- Langford NJ, Ferner RE. Toxicity of mercury. Journal of human hypertension. 1999 Oct;13(10):651-6.
- Bernhoft RA. Mercury toxicity and treatment: a review of the literature. Journal of environmental and public health. 2012 Oct;2012.
- Hyson Jr JM. Amalgam: Its history and perils. Journal of the California Dental Association. 2006 Mar 1;34(3):215-29.
- Mackenzie, L. (2021). Dental amalgam: a practical guide. Dental Update. https://doi.org/10.12968/denu.2021.48.8.607.
- Antony K, Genser D, Hiebinger C, Windisch F. Longevity of dental amalgam in comparison to composite materials. GMS health technology assessment. 2008;4
- Golding J, Steer CD, Gregory S, Lowery T, Hibbeln JR, Taylor CM. Dental associations with blood mercury in pregnant women. Community dentistry and oral
epidemiology. 2016 Jun;44(3):216-22.
- Dodes JE. The amalgam controversy: an evidence-based analysis. The Journal of the American Dental Association. 2001 Mar 1;132(3):348-5

54. Thank You!