A filling is a material used to replace part of a tooth that was destroyed by decay (a cavity).  The cavity is cleaned out and shaped.  Then the filling is placed to restore the tooth to it's normal shape and function.

What is Amalgam?

Dental amalgam (silver filling) is an affordable and durable material that has been used to restore the teeth of more than 100 million present-day Americans.  In the past 150 years, amalgam has been used to restore billions of teeth worldwide.

Amalgam is a metal alloy made of a mixture of metals such as silver, copper, tin, and zinc, in addition to mercury which chemically binds all the components into a hard, stable substance.

An amalgam filling is formed by mixing the powdered metals with liquid mercury forming a paste, and then pressing the material into the prepared area in the tooth.  The initial hardening takes a few minutes after which the filling is shaped to follow the natural contours of your tooth.

Typical amalgams

Is Amalgam Safe?

If you use an internet search engine and look up "dental amalgam safety"  you will find thousands of pages of information.  A recent Google search provided over 50,000 results.  The credibility of those authors however will vary immensely.

Some of those pages will tell stories about health problems caused by amalgam and claim that removing amalgam fillings cured diseases such as multiple sclerosis overnight.

But other pages will discredit those stories by applying scientific principles and reassuring us that amalgam is safe.

But You Didn't Answer My Question!

Exactly.  There is so much controversy surrounding the issue that it has become increasingly difficult to give a straight answer.  But one thing we can do is stick to the facts.

Amalgam FACTS:

• For the year 2002, a warning was issued to us by the state of California that must be displayed to the public.  The warning sign reads exactly as follows:

• Amalgam use in the U.S. is declining.

• Elemental, free mercury is poisonous.

• Amalgam contains about 40% mercury which initially is elemental but upon mixing of the amalgam changes form.

• Most of the mercury in amalgam is chemically trapped and cannot escape.

• Some mercury does escape during the life of the filling.

• No scientific studies have shown that the amount of mercury that escapes from amalgam fillings can be harmful.

• Air, food, and water contain mercury too.

• There is some mercury in your body right now even if you have no amalgam fillings.

• A new law for 2002 requires that each patient who needs fillings receive the Dental Materials Fact Sheet published by the Dental Board of California to describe alternative filling materials.

• There are alternatives to silver fillings such as white fillings.

• Most insurance companies cover only amalgam fillings for back teeth.

• The U.S. Food & Drug Administration has reported that amalgam is a safe choice for a restorative material.

• At Glendale Dental Arts, over 95% of new fillings placed are white, not amalgam.

• Many patients request us to change their amalgam fillings into white fillings, even though their silver fillings are in good shape.

• Keep reading...

Important Amalgam Properties

Amalgams are made of metal.  Therefore they share the properties that most metals do, namely:

1. Thermal conductivity

   When something hot or cold enters your mouth , a silver filling, can quickly transfer the temperature deep into your tooth and stimulate the nerve, causing trauma and sensitivity.

2. Electrical Conductivity

   When a new silver filling is in reach of another metal object such as a metal crown on a nearby tooth, electricity will be transferred between the two metals, sometimes causing a "zing" feeling.

3. Temperature related expansion and contraction

   * IMPORTANT *

   When something hot (coffee, food, etc.) comes in contact with a silver filling, the metal filling will expand and push against the walls of the tooth.  When the filling cools off, or when it contacts something cold (cold drinks, fruit, etc.) it will shrink and relax the pressures on the tooth.

   This cycle happens many times while you eat and drink.  After enough repetitions of this cycle, the tooth can crack.  If the filling is small, and the tooth is strong, this may take many years to happen, or may never happen.  But if the filling is large, this can happen more quickly.

   

When a cavity is being prepared for a silver filling, a certain amount of tooth structure needs to be drilled out so that the filling can be held in place and be large enough for strength.  Amalgam fillings are not considered "conservative" on teeth because more tooth needs to be drilled out than the cavity had damaged.

Do Amalgams Last Longer Than Composites?

Yes and no.  It depends on the size of the filling and the strength of the tooth.

If the tooth is strong and the filling is small, both amalgam and composite will last about the same amount of time.  If the filling is very large, then amalgam might last longer than composite if the tooth is strong enough to support the amalgam.

Amalgams are metal, making them stronger than composites.  But some amalgams, especially large ones, can damage or weaken teeth, shortening the lifespan of a tooth.  So although the strong metal filling is still intact after say 10 years, the tooth no longer can support the filling.  The damaged or weakened tooth might need a crown, or root canal, or if it was cracked too deeply might need to be extracted.

Composites are resin, making them slightly weaker than metal, just like your natural tooth is.  But composites are more gentle on teeth.  If properly maintained, a tooth with a composite filling can outlive a tooth with an amalgam filling.  Composites can be easily renewed by sealants whereas amalgams cannot.

So the real question is,

"Will a tooth last longer with an amalgam or with a composite?"

And we believe the answer to that question is almost always composite.  There are certain exceptions which will be explained if they apply to your specific case.