MERCURY HAZARDS AND

TOXICITY

Under the guidance of :Dept of conservative dentistry and endodontics

NORTH BENGAL DENTAL COLLEGE AND HOSPITAL

INTRODUCTION• Mercury is a known toxic , bio accumulative

substance and it often finds its way into body through dental amalgams, which is used to restore cavitated tooth.

• The mercury release in body and negatively affect brain, nervous system, kidney etc.

mercury in dental amalgam The silver fillings used by dentists to restore teeth are composed of a metal

"amalgam" containing roughly 50% elemental mercury and 50% other metals (mostly silver with some tin and copper).

The mercury found in amalgam fillings has raised some safety concerns over the years. Amalgam can release small amounts of mercury vapor over time, and patients can absorb these vapors by inhaling or ingesting them.

Dentists all over the world remove millions of amalgam fillings every day, with no regard for the possible mercury exposure that can result from grinding them out.

Taking out fillings with a high speed dental bur generates a cloud of particles, at least 65% of which are one micron or less in size. These are fully respirable, get deep into the lungs, where the microscopic particles are broken down and the mercury is systemically absorbed within a few days.

MERCURY EXPOSURE IN DENTAL OFFICEMercury exposure in dental office can occur- When Amalgam raw material being stored in use. During trituration , insertion & intraoral hardening. From amalgam scrap. During finishing & polishing. Removal of old restoration.

TOXIC EFFECTS OF Mercury DEPEND UPON

Amount of exposure. Length of exposure. Length of mercury accumulation in body. Amount of accumulated mercury Overall health of the patient ( for detoxification).

Amount of mercury releasedDuring manipulation of amalgam

TRITURATION 1-2µg

CONDENSATION 6-8µg

DRY POLISHING 44µg

WET POLISHING 2-4µg

REMOVAL OF AMALGAM RESTORATION UNDER WATER SPRAY AND HIGH VOLUME SUCTION 15-20µg

ADDITIONAL EVAUATION FOR 1 MIN TO REMOVE RESIDUAL AMALGAM DUST 1.5-2µg

.

How mercury enter into body from amalgam restoration …..

MERCURY SYMPTOMS ON ORAL CAVITY

Bleeding gums Alveolar bone loss Loosening of teeth Excessive salivation Foul breath Metallic taste Burning sensation, with tingling of lips, face Tissue pigmentation (amalgam tattoo of gums) Stomatitis (sores in the mouth) Ulceration of gingiva, palate, tongue

OTHER TOXIC EFFECT OF MERCURY ON BODY G.I.T PROBLEMS Cramps Inflamed colon Diarrhea C.V.S PROMBLEMS Weak pulse Increase B.P Chest pain/feeling of pressure In the chest area RESPIRATORY PROMBLEMS Weakness and problems with breathing Emphysema Persistent cough

NEUROLOGICAL PROBLEMS Headaches Vertigo Tinnitus Twitching in various areas of the body (eyelid, feet etc.)

DENTAL MERCURY Hygiene RECOMMENDATIONS

Ventilation: Provide proper ventilation in the place by having fresh air exchanges and periodic replacement of filters, which may act as traps for mercury .

Monitor office: Monitor the hg vapor level in the office periodically. This may be done by using dosimeter badges & vapor analyzer(limit – 50µg/m³ 8 hr shift over 40 hr work week).

Monitor personnel: monitor office by periodic analysis.Office design: Use proper work area design to

facilitate spill containment and cleanup .

DENTAL MERCURY Hygiene RECOMMENDATIONSPre-capsulated alloys: Use pre-capsulated Alloy. Eliminate the possibility of a bulk hg Spill, otherwise store bulk hg properly in unbreakable containers on stable surface.Amalgamator cover: use an amalgamator fitted with a cover.Handling care: use care in handling amalgam avoid skin

contact with mercury or freshly mixed amalgam avoid dry polishing.

Evacuation systems: Use high volume evacuation when finishing or removing amalgam .Evacuation system have traps or filter. Check, clean / replace traps and filter periodically.

DENTAL MERCURY Hygiene RECOMMENDATIONS

Masks: Change mask as necessary when removing amalgam restoration.

Contaminated items: Dispose of Hg contaminated items in sealed bags according to applicable regulation .

Spills: clean up Hg properly by using bottle tapes/ fresh mixes of amalgam to pick- up droplets/ use commercial clean up kits. Do not use household vacuum cleaner.

Select an appropriate alloy: Proper Hg: alloy ratio to avoid the need to remove excess Hg before packing.

DENTAL MERCURY Hygiene RECOMMENDATIONS

Recycling: store amalgam scrap under radiographic fixer solution in covered container. Recycle amalgam scraps through refiners .

Clothing: Wear professional clothing only in dental operatory.

Avoid carpet/floor coverings in dental office ; floor coverings should be easy to clean, nonabsorbent and seamless.

Use rubber dam during insertion, condensation, and polishing of amalgam.

APPROPRIATE DENTAL CLINIC SHOULD BE….

Gallium based alloy: - Gallium was discovered in 1875 .it is metalWith similar atomic structure and characteristicsTo mercury and has a melting temp of 29˚c. Hence , by 1928 Puttkammer

suggested Gallium as a substitute for mercury It is available as :1. Gallium Alloy 2. Galloy DISADVATAGES . Handling characteristics of alloy not favorable . High level of corrosion is seen which causes loss of strength marginal disintegration and marginal fracture in chunks. . Dimensional change of 21.5% . Poor biocompatibility . Costly.

OTHER OPTION TO REDUCE MERCURY HAZARDS:

MERCURY FREE ALLOYS

TREATMENT OF MERCURY TOXICITY

• Chelation therapy is the administration of chelating agents to remove heavy metals from the body.

Chelation agent are chemical substances that contain molecules capable of bonding securely to minute particles of metal called ions. In addition to directly supporting vital body functions, this bonding process---called Chelation---provides a means of trapping harmful metals in your bloodstream and making them susceptible to safe excretion in urine. The process of Chelation, called Chelation therapy, is commonly used in the treatment of heavy metal poisoning

A chelating agent could be given orally, intramuscularly, or intravenously.

Chelation therapy for acute inorganic mercury poisoning can be done with DMSA, 2,3-dimercapto-1-propanesulfonic acid

(DMPS), D-penicillamine (DPCN), or dimercaprol (BAL).[1] Only DMSA is FDA-approved for use in children for treating

mercury poisoning.

correct dosage is required, as inappropriate dosages increase toxicity.

Reference:1) sturdevant’sart and science of operative dentistry.

2) textbook of operative dentistrynisha garg, amit garg.

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