Grey Spot
Thursday November 2, 2006 

Dear Dr. Mady: Dear Dr. Mady: I recently had a root canal and a crown done on one of my molars because it was badly decayed. Does this mean that I will never get another cavity in that tooth?—Samantha in Nassau


Dear Samantha: It is a common belief that once a root canal, filling and/or crown had been done on a tooth, that that tooth won't ever decay again. This is absolutely untrue and any tooth that remains in your mouth while you are alive is susceptible to caries (tooth decay).

If a tooth requires a root canal, as your molar did, then the nerve was probably necrotic (dead) or had been invaded by a cavity and the tooth was at risk of forming an abscess if it had not already. Root canal treatment, also called endodontic treatment, involves relieving pain and discomfort by basically removing the nerve from a tooth. The procedure involves opening the tooth with a small hole through its biting surface to expose the nerve (pulp) which is then removed using fine metal rotary or hand files. The space where the nerve was in the roots is replaced with a rubber material called gutta percha. Ultimately, the intention of this therapy is to allow you to keep your tooth for a longer period, which will help to maintain your natural bite and the healthy functioning of your jaws. The only other alternative is extraction and I'm positive that your dentist would agree that it is not the optimal treatment choice. The tooth itself still remains, comprised of enamel, dentin (the layer under the enamel) and cementum (the layer covering the roots) and any of these three structures can be broken down from attacks of acid from bacteria and sugars. The only difference now is that the cavity will go unnoticed unless you see it or feel it with your tongue.

Crowns are a restorative dental treatment option that consist basically of a complete covering or cap over your tooth or teeth. They are used to restore teeth that are worn, badly broken down, structurally compromised, cosmetically unpleasant and often teeth that have had root canal treatment. These restorations are usually composed of metal, porcelain or a combination of both. Yes they do cover all or most of the clinical crown of a tooth. The clinical crown is the portion of the tooth that shows in the mouth above the gums. What is important to understand is that good oral hygiene is still mandatory because crowned teeth can get cavities later around the margins where the crown meets the natural tooth and also on the root surfaces, especially if the gums recede back over time after treatment. If the marginal integrity of the crown where it meets the tooth is poor, this does not help the situation. Also if any decay, even microscopic, is left under the crown, a cavity can evolve undetected and the end result years later can be devastating and the tooth may end up needing to be extracted.

Teeth restored with fillings, whether amalgam or composite resin, are also susceptible to future decay for the same reasons as a crowned tooth. Maintenance and good oral health are what it is all about. The key to good oral health is excellent oral hygiene and home care. Once restorations of any type are placed, these are extra areas that have to be concentrated on because they are areas where there is an increased possibility of plaque collection at margins and surfaces.

Make sure that you always brush at least twice a day, after breakfast and before bed preferably. When buying a toothbrush, always purchase a soft or ultra-soft bristle type and direct the brush at a forty-five degree angle placing the bristles inside the cuff of the gum where it joins the tooth. Without too much force gently brush back and forth rolling up and out. Brushing can remove plaque from three out of five surfaces of teeth, but proper flossing can clean the other two surfaces. So floss daily no matter what and keep your regular checkup appointments with your dentist. This is the most important part of the maintenance program.

If you need any other information or have any dental questions, please e-mail Dr. Mady at

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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