Amalgum is alloy mercury with another metal or metals.
Mercury is liquid at room tempreture and freezing point is -390c.
It can readily undergo amalgamation reaction with metals such as silver, tin and copper.
High copper amalgams has significantly improved clinical performance of amalgam.
Composition of amalgam
- Ag 58-70%
- Sn 18-30%
- Cu 12-22%
- Zn 0.5-1%
Mercury is used to; Bind the metals together and to provide a strong, hard durable filling.mercury is the only element that will bind these metals together in such a way that can be easily manipulated into a cavity.
Zinc; reduce incidence of fracture of margins by 45% and act as a scavenger during production of alloy (react with oxygen and form stag which can easily removed.
Zn free amalgams are made in intert atmosphere to prevent oxidation during melting.Zn containing amalgams can be contaminated with moisture during condensation.
Zn + O2 = ZnO + H2
Liberated hydrogen can cause delayed expansion of amalgam.
Classification of amalgam
- Conventional amalgam-Less than 6% copper
- Copper enriched amalgams-6-30% copper
Mercury in dental amalgam safe?
Dental amalgam is a safe and effective restorative material
Dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc, which forms a safe, stable cavity-filling material. It's important to note that dental amalgam has entirely different properties than mercury by itself.
Mercury in dental amalgam is not poisonous. When mercury is combined with other materials in dental amalgam, its chemical nature changes. so it is essentially harmless.
The amount released in the mouth under the pressure of chewing and grinding is extremely small (1-3 micrograms) and no cause for alarm.
In fact, it is less than what patients are exposed to in food, air, and water (5-7 micrograms a day)
Ongoing scientific studies conducted over the past 100 years continue to prove that amalgam is not harmful.
Claims of diseases caused by mercury in amalgam are anecdotal, as are claims of miraculous cures achieved by removing amalgam. These claims have not been proven scientifically
Why do dentists use dental amalgams?
Dental amalgam has withstood the test of time, which is why it is the material of choice. It has a 150-year proven track record and is still one of the:
· Least expensive materials to a fill a cavity.
It is estimated that more than,1 billion amalgam restorations are placed annually.
Dentists use dental amalgams because, It is easier to work with than other alternatives.
Some patients prefer dental amalgam to other alternatives because of its
safety, cost-effectiveness, and ability to be placed in the tooth cavity quickly
Why don't dentists use alternatives to amalgam?
Alternatives to amalgam:
Alternatives to amalgam:
· cast gold restorations
· Composite resins are more costly.
Gold and porcelain restorations take longer to make and can require two appointments. Composite resins, or white fillings, are esthetically appealing, but require a longer time to place the restoration. It should also be known that these materials, with the exception of gold, are not as durable as amalgam
What about patients allergic to mercury?
The incidence of allergy to mercury is far less than one percent of the population.
People suspected of having an allergy to mercury should receive tests by qualified physicians, and, when necessary, seek appropriate alternatives.
Are staffs occupationally exposed?
Dentists are using pre-mixed capsules, which reduce the chance of mercury spills.
And newer, more advanced dental amalgams are containing smaller amounts of mercury than before.
Because dental staff are exposed to mercury more often, one would expect dental personnel to have higher rates of neurological diseases, such as multiple sclerosis. They do not.
What are other sources of mercury?
Mercury can be found in:
Mercury can be found in:
We are exposed to higher levels of mercury from these sources than from a mouthful of amalgam.
Are amalgam dental restorations containing mercury safe for children?
Children who received dental restorative treatment with amalgam did not score significantly better or worse on neurobehavioral and neuropsychological assessments than children who received resin composite material. Children who receive restoration with resin may be more likely to need additional treatment. Studies evaluating outcomes for longer than 5 to 7 years are needed.
Dental mercury hygiene
- Alert-during training we need to observe good Hg hygiene practice
- Ventilation-fresh air exchanges AC plants act as Hg reservoirs. Therefore filters should bee replaced with time.
- Surgery atmosphere should be checked periodically
- Do not carpet the floor. Sheet flooring up to 10cm of wall.
- Hg storage-Unbreakable, tightly sealed, and store away from heat.
- Use single use capsule sealed during amalgamation
- Avoid removal of excess Hg and use correct Hg: Alloy ratio
- Use a totally enclosed amalgamator
- Hg dispensers handle with care and heck regularly for any leaks
- Check orifice for residual Hg.
- Hg should not touch with bare hands
- All amalgam scrap and Hg stored in a tight container and discard under radiographic fixer solution.
- Spilled Hg immediately cleaned and placed in a scrap jar
- Do not heat Hg or amalgam and instruments, clean them before heat sterilization
- Do not use ultrasonic amalgam condensers
- Remove old amalgams and polish under copious air water spray and high volume evacuation exhaust outside the surgery
- Wear a mask
- All the abrasions and cuts in the skin should be covered prior to handling the amalgam
- Disposable material contaminated with amalgam disposed properly
- Waste water systems-place Hg traps
- Skin contaminated with Hg should washed thoroughly with soap and water
- Do not eat, drink, smoke inside the surgery
- If Hg toxicity problem suspected-urine analysis done for Hg.