How do a cavity get started?

The bacteria in your dental plaque converts the sugar that you eat into the acid through the process known as fermentation. In biochemistry, it is estimated that one glucose (sugar) molecule can ferment into two molecules of pyruvic acids.

Silver amalgam and composite resin are the two most common materials used to restore teeth damaged by decay. There are situations where one material is preferable over the other, and similarly, there are disadvantages to both of these filling materials. Additionally, there are some health experts who question the safety of amalgam fillings and say they should not be used under any circumstances.

Silver amalgam - a health hazard?

The American Dental Association's official position regarding silver amalgam is that it is a "safe, durable and cost-effective material that dentists have used in tooth restorations for more than 150 years." But there are some practitioners who have expressed serious concern over the safety of amalgams, and the controversy over its use continues.

What is causing such concern?

It's the fact that amalgam is composed of 35 percent silver, 15 percent tin or tin mixed with copper, a trace of zinc, and 50 percent mercury - a highly toxic heavy metal.

Anti-amalgam dentists point out that the amalgam releases mercury vapor when there is friction on the surface of the filling, such as when you chew. Mercury vapor is cyto-toxic, which means that it kills cells, even when the exposure is minute.

Mercury is absorbed through the lungs and into the arterial blood and is stored by your body, primarily in your kidneys, liver and brain. And no level of this mercury vapor is considered safe. However, the ADA counters that, once bound to the other metals, the mercury in dental amalgam is completely harmless.

While it is highly unlikely that such small concentrations of mercury can or do harm the typical human, there is a remote chance that persons who have immunocompromised systems could have some negative influence from this mercury presence, or the presence of other metals," said Gordon J. Christiansen, D.D.S.,M.S.D., Ph.D. Also, those allergic to mercury should not have amalgam fillings placed in their mouths

It's important to note that no controlled scientific studies have been conducted that demonstrate ill effects to human health resulting from amalgam fillings. The evidence, to date, is all anecdotal. The World Health Organization has stated that it recognizes the importance of continued monitoring of the safety and effectiveness of all dental restorative materials, including dental amalgam.

Amalgam's advantages

Silver amalgam is a more durable tooth filling material than composite resin in teeth that are subjected to a lot of biting pressure. An amalgam filling costs considerably less than a comparable composite filling.

The disadvantages of amalgam

Silver fillings are less attractive than tooth-colored composite resin fillings; for this reason, they're typically not placed in teeth located near the front of your mouth

The mercury in amalgam fillings expands and contracts with heat and cold (think of the mercury in a thermometer). This can eventually cause the filling to fracture your tooth, so a crown will be required to restore its functionality. Silver fillings will eventually corrode and leak, which can cause new decay to develop underneath the filling. The leakage can also give a gray appearance to the entire tooth.

Tooth-colored composite resins - the pros and cons

Resin fillings result in a natural-looking smile. The color can be closely matched to your natural teeth, so the restorations are nearly undetectable. And because the resin compound actually bonds to your tooth, the seal is tighter and the restored tooth can be even stronger than it was before. Composite resin fillings can also be made much smaller than an amalgam filling used to restore the same amount of decayed tooth, so less natural tooth structure is lost. The durability of resin tooth-filling material has not been time-tested, but continual improvements in the product have made resins nearly as durable as amalgam fillings.

So where's the catch?

In the cost. A resin filling costs about 150 to 200 percent more than a comparable silver filling.

Which to choose?

Overall, resin fillings are a more conservative treatment, because less of your natural tooth structure needs to be removed in preparation for their placement. They also do a better job of protecting your tooth in the long run, as there's less chance that your tooth will fracture and require a crown in the future.

Ultimately, the choice is a personal one for both dentists and patients. Do amalgam's benefits outweigh the possible risks? Are tooth-colored fillings worth the significant extra cost? Which filling material will prove to be most cost-effective in the long run? We recommend that you research your options, discuss them with your dental healthcare providers, and choose the filling material that's right for you, based on what you've learned

Replacing Silver Fillings

Everything wears out, and your silver fillings are no exception. They have to endure an incredible amount of biting force each day, and as they age, their appearance and function degrade

Over time, amalgam fillings often absorb moisture, causing them to swell and break away from the tooth. When this happens, your tooth is no longer sealed and protected from decay. Food and bacteria can become trapped in this space, enabling cavities to form.

What material will be best for restoring a worn silver filling?

When we recommend a restoration to replace your worn silver filling, we'll consider both the size of the filling and the amount of healthy tooth structure that remains. We can replace a fairly small filling with another silver filling, but you should know that eventually, it will probably wear out and have to be replaced again. Silver fillings have some disadvantages that should be considered when it's time to replace your filling.

Silver fillings are less attractive than tooth-colored fillings.

Amalgam expands and contracts in response to temperature changes in your mouth. This can eventually cause the filling to fracture your tooth, so a crown might be required to restore its appearance and functionality.

Silver fillings are vulnerable to metal fatigue and will likely corrode and leak as they age, which can cause new decay to develop underneath the filling. The leakage can also give a gray appearance to the entire tooth.

Replacing large fillings

If your worn filling is fairly large and less of your natural tooth structure remains, there,s an increased likelihood that your tooth could fracture, or even break away entirely. If this is the case, we'll recommend a gold or porcelain onlay or crown to strengthen your tooth and restore its function, preventing more serious problems from arising in the future.

Worn Whilte Fillings on Front Teeth

Everything wears out eventually, and white plastic fillings are no exception. As white fillings in front teeth age, they absorb moisture, swell, and begin to leak. This filling has lost its seal and no longer fully protects the tooth from cavities. When they're small like this, it's easy to replace them with new plastic fillings. But sometimes, front fillings fail in another way. There's a tremendous amount of force on the edges of teeth when you bite together. As you can see here, some of the tooth broke away from the biting edge as a result of biting pressure. To strengthen the tooth and protect it from future damage, crowning or bonding may be necessary.