Dental updates from Dr. Mckeever.

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ESTHETIC DENTISTRY - KNOW WHAT YOU ARE GETTING!

It still has not been determined whether restorations that are esthetically pleasing (tooth colored) provide the same length of service offered by traditional metal restorations. Any health benefits linked to a particular type of restorative material also remains elusive. Many dentists choose not to replace their own gold or silver amalgam posterior restorations (on molar teeth) or have new cavities restored with the newer materials. A Web-based survey yielding responses from 757 dentists having a total of 5908 molar teeth found that silver amalgam and gold were their "materials of choice" when it came to the restoration of their own teeth; only 23% had the newer materials used on themselves. Silver amalgam has been used for more than 100 years to fill molars (and premolars). The newer materials include composite resin, glass ionomer and ceramics. The use of these materials is expected to exceed that of silver amalgam and gold in the future because of the various cosmetic and (percieved) health issues that make them more attractive. However, in spite of what some dentists might tell you, there can be some drawbacks to using (or over-using) these products.

First of all, resin composite "fillings" do not last as long as silver amalgams. There are several reasons for this the main one being that composite fillings are very technique sensitive (i.e. hard to place properly). This is because they have to be bonded to the teeth and the bonding process is subject to operator error. In fact, two of dentistry's top dental materials and clinical investigators have said that over half of the dentists cannot place a satisfactory two surface posterior composite filling. Also, composite shrinks which can result in two problems; the tooth that is being treated can be left very sensitive and gaps can form between the filling and the tooth making the tooth more susceptable to re-infection with cavity germs, especially in the areas below the gum line. And, the bond of the composite to the tooth, while initially quite strong if done properly, will inevitably weaken over the years.

Some dentists tell patients that the mercury in silver fillings will cause them long-term medical problems. This has been investigated many, many times and it has been found that this is so much you-know-what. They will try to replace your old silver fillings with resin composites or ceramics based upon that myth. (Dentists that preach this sermon can have their licenses suspended). In truth, there are also toxic properties found in composite materials. They release estrogen compounds into the oral cavity and they can be allergenic to some patients. Is this clinically significant? Probably not but neither is the small amount of mercury released from silver amalgam fillings. Also keep in mind that the composites are anywhere from 1.5 to 3.5 times more expensive than amalgams to place mostly because it takes that much more time to place them properly.

The best material for onlays and full caps is still gold although dentistry has come a long way in its effort to make stronger indirect (made by a dental laboratory) tooth-colored restorations. Most lab-fabricated restorations are made out of a ceramic material which is glass! I'm sorry but with up to 600 p.s.i. biting pressure on molar teeth, glass is eventually going to break and, since the jaws function like a nutcracker, the farther back in the mouth that glass is positioned, the easier it can break; i.e. the closer the nut is to the fulcrum (the jaw joint) the easier it is to crack.

Now, do I place tooth-colored restoration? You bet I do because not many people want a gold or silver tooth toward the front of the mouth. But neither should they want weak restorative material in areas where there is a high likelihood of breakage. In fact, I so strongly believe in the nutcracker theory (over 80% of all broken teeth I see are second molars which sit in the "nut" position) that, when restoring second molars, I have my patients sign a release stating that, if they insist on tooth-colored crowns on these teeth, I am not responsible for any breakage of that restoration that might happen before my usual five-year warranty is up.

My whole reason for this column is to urge all dental patients to know what they are getting and to ask their dentists some questions before any restorative dental work is started. Consider every restoration done in your mouth to be of a temporary nature because, eventually, most dental work will fail not because of poor work but because of materials. The stronger the materials used for a given situation, the less chance of having a re-do on down the line. However, since we live in an esthetic-conscious society, there must be trade offs in the appearance v.s. durability tug-of-war and most all of our materials are pretty darned good if handled properly.




posted by Steve at 9:30 PM