Different Filling Materials
Thursday December 5, 2002

Dear Dr. Mady: What is the real difference between gold or amalgam fillings and white fillings and are the amalgam ones really dangerous? Also, do dentists still do amalgam fillings? -Elias in the west end.

Dear Elias: Due to the fact that there are so many other, more attractive restorative dental materials, other than silver amalgam, available today, most people will not even choose amalgam type fillings. The truth is that those gold and even silver amalgam fillings still are the strongest and last the longest.

Dentists use various restorative materials to repair teeth that have been stained, fractured, decayed or that are even misshaped. Included amongst these and the most common are tooth-colored composite resins. These materials are an excellent choice for treating teeth.

With respect to your molar teeth that do most of the day-to-day chewing and grinding, durability is of utmost importance. On these teeth, metals are a good option because of their superior strength. They can help prevent breaking and cracking and seem to wear better than composites (polymer-based or plastic). Also, as the portion of the tooth that is missing increases, the more useful that gold and silver amalgams become.

Often individuals wonder what amalgam means. It is basically an amalgamation or trituration of various metals into one solid mass. The main metal is silver, of course, but there are also certain small percentages of copper, zinc, tin and mercury. The catalyst that causes all these powdered metals to join and harden is mercury. This is also the ingredient that has given amalgam fillings such a bad reputation.

Mercury has been blamed for everything from Alzheimer's and memory loss to aches and pains. Many studies have ruled out or not proved this, but the fact remains that mercury is poisonous and many feel that they do not want to place something in their body that they know may be unhealthy. There are rumors that every time you chew with amalgam restorations, mercury vapor is released and ingested. This is also hard to prove. The fact is that amalgam is still an excellent choice for a dental restorative material but your dentist can give you other options.

Many people wish to have all their old silver fillings replaced with new tooth-colored materials. This is an individual's own personal decision to make, but if you are concerned about mercury vapor and if it is true that vapor is released, more would be released from the removal, than it would from years of chewing. Also, if you have had a problem with severe or rampant tooth decay in the past, you are probably better off to maintain your amalgam restorations. History so far shows that they leak less and last longer.

Composite restorations do have their advantages in addition to esthetics. Far less tooth structure has to be removed when placing these because they rely on bonding, as opposed to retention from size and undercuts as in the case of amalgam. The tooth must first be prepared and then is treated with a conditioner. After, a bonding agent is applied and then layer-by-layer the missing tooth structure is replaced and each application is cured with a blue light. The color can be matched exactly and the final result can be polished and adjusted immediately. With amalgam, the dentist has only a few minutes of working time once the material is mixed and it cannot be polished until the next day and if there is a desire to add to the filling, the entire restoration must be replaced. Less skill and time is required to make the amalgam filling adhere to the tooth, however.

Another option for rebuilding teeth is to place ceramic porcelain restorations. These are esthetically pleasing, but they require even more labor and appointments due to the fact that they must be made indirectly outside of the mouth using a model of the teeth or tooth in question. The cost is also significantly higher than it is for the other choices and a temporary restoration must always be fabricated.

Newer composite resins may even be comparable with amalgams especially for small cavities, and the metal in amalgam is more of a thermal conductor and can cause teeth to be more temperature sensitive. Some composite resins (glass ionomers) even release fluoride to help prevent recurrent tooth decay.

The bottom line is that despite what anyone claims, tooth colored restorations are always favored over amalgam or any metals despite the increase in cost, and durability issues. In fact I would have to say that 85 percent would rather have tooth colored fillings, even though they don't last as long and cost a bit more. Your dentist can inform you with sound advice and recommendations, and the final choice is yours.

This column is reprinted with the permission of the author and The Windsor Star. "Ask the Dentist" is written by Windsor dentist (and ECDS member), Dr. David Mady Jr.. The column appears the first Thursday of each month in the Windsor Star. Readers with questions can write to "Ask The Dentist", c/o The Windsor Star, 167 Ferry St., Windsor Ontario, N9A 4M5



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