Every dentist has experienced it before. Patients refuse x-rays because they don’t want to be exposed to too much radiation. What is “too much radiation?” That’s a great question.
Medical professionals have been taught since the 1940’s that medical and dental imaging carries a tiny chance of increasing a person’s cancer risk, no matter how low the dose. The model that we were taught is called the “linear no-threshold model” (LNT) and it basically claims that any dose of radiation, no matter how small, carries an increased risk of causing cancer. As dentists, we are supposed to weigh this tiny (but not zero) increase in risk against the benefits of whatever x-ray image we wanted to see.
New research published in the American Journal of Clinical Oncology has re-evaluated the original research that we based the LNT model on and has found it to be unconvincing. The original research was performed by exposing fruit flies to various doses of radiation. The damage at each level was measured and the research made the assumption that there is no completely risk-free level of radiation.
In the LNT model, the well-established cancer-causing effects of high doses of radiation are extended downward in a straight line to very low doses. The LNT model assumes there is no safe dose of radiation, no matter how small. However, the human body has evolved the ability to repair damage from low-dose radiation that naturally occurs in the environment.
Basically, the radiation doses that were studied in the 40’s were much to high to extrapolate into low dose medical uses of radiation. We’ve based our concerns about x-ray radiation on doses that are much higher than those experienced by patients. The recent paper was specifically about CT scans, which actually have a much higher exposure to radiation than dental x-rays.
As a profession, dentistry has gone out of its way to expose patients to as little x-ray radiation as possible. But many patient still balk. The effectiveness of x-rays for dental diagnosis cannot be underestimated. But not only are they effective, current research suggests that they are completely safe.
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Gather round, children. I want to tell you a scary story. It’s the true story of a tooth. It was a tooth that was long thought to be dead. You see, the owner of this tooth was a 60+ year old man who had bumped it on a manure spreader when he was nine. Over the years, the tooth went dark. It never really hurt him, it just changed color. He got used to it over the years and just thought it was dead.
Then it happened. One dark and rainy night, some 50 years later, something changed about that tooth. He started to notice some feeling in that tooth. Some pressure. It felt different. It didn’t hurt, exactly. But something was different. He went to bed thinking it would go away.
He was wrong…very wrong.
He was awakened from a dead sleep with a sharp pain under his lip. The pain was intense and throbbing. It hurt so bad, he was ready to try and take that tooth out with his bare hands. And his dentist’s office didn’t open for another 4 hours! It was like a horror movie that had come true. The tooth he always thought was dead…had come back to life! And it was haunting him!
Have you ever seen someone with a dark front tooth? It’s relatively common in adults and very common in children. Most often it happens after some kind of trauma. Like a kid that bumps their front tooth on a coffee table or a guy to gets hit in the face with a softball. Sometimes these teeth turn dark. The dark color is actually an indication of the pulpof the tooth becoming necrotic. Necrotic is a fancy term for tissue death. So what we’re really talking about is a dead tooth.
Necrotic teeth usually become abscessed teeth. An abscess happens when the immune system’s response to the trauma is so heavy that pus actually leaks out of the gum tissues! Although most people are grossed out by talk of pus, it’s pretty important. Pus is simply the dead cells that our immune system uses to cause inflammation, which is a response to infection or a foreign body. Often the teeth do become infected but if the injury is only from trauma, sometimes there isn’t true bacterial invasion in these teeth.
A tooth that has become necrotic needs treatment. It either needs to be removed or it will need root canal therapy. When these teeth aren’t treated, they usually stay chronically inflamed. This chronic inflammation often doesn’t hurt, but it’s almost always doing damage to the surrounding tissues. An untreated tooth with this kind of injury has the potential to become a zombie tooth.
Zombie teeth are dead and chronically inflamed. They almost never hurt…until they do! It’s like a classic slasher movie. Everyone is relieved when they think Jason or Freddy is dead. But they always come back to life!
Do yourself a favor…if you’ve got a zombie tooth make sure you get in to see your dentist! These teeth have a way of not being a problem until holidays and weekends!
Did you find this post horrifying? Did it scare you to death? I’d love to hear about it! You can share any Mead Family Dental post with a “Like” on Facebook, a “+1″ on Google+ or you can even “Tweet” it with Twitter! All you need to do is hover over the heart shaped button next to the title of the post. Or you can leave a comment by clicking on the balloon shaped icon next to the title.
Last week I was talking to a patient about a tooth they were having a problem with. The tooth was badly broken and the patient assumed that it would need to be removed. I explained to the patient that taking the tooth out was one option that would solve the immediate problem. Losing this tooth would create a new problem…what to do with the space created by losing the tooth. But that, my friends, is whole other blog post.
Another option for that tooth is the most poorly named procedure in all of dentistry: the “root canal.” Root canal therapy (a.k.a.: root canal) is probably the most misunderstood dental procedure. So what is a root canal? It’s actually a description of part of your tooth. The tooth is made of 3 distinct layers. The outer layer is called the enamel on the crown of the tooth and the cementum on the root surface (below the gum line). This outer layer is great protection to the inner layers of the tooth, but it’s very brittle unless it’s attached to the next layer in, the dentin. The dentin is softer than the outer layers and it’s made up of small tubes going from the outside toward the center of the tooth. The third layer of the tooth is at the very center and is called the pulp. The pulp is made up of connective tissueand contains the blood vessels and nerve tissue of the tooth. The pulp is very aptly named because it’s a soft, smooshy mess of tissue that is contained by a space in the dentin called the “root canal.”
The pulp is actually pretty well defended by the outer layers of the tooth, but if tooth decay invades deep enough into the tooth or the tooth is broken, the pulp can become infected with oral bacteria. Your immune system puts up a pretty good fight, but usually once the pulp has been invaded, the pulp tissue will eventually die. If this happens, the entire root canal space can become infected which is what we call an abscess.
Root canal therapy is done when the pulp tissue is damaged or infected. The goal of root canal therapy is to clean out the damaged pulp tissue from the root canal, then disinfect the root canal space and seal it from top to bottom so that oral bacteria can no longer gain access into the space. A dentist does this by drilling a hole through the crown of the tooth and using tiny instruments to remove and clean this space. Then a filling material is packed into the space to seal the tooth up. Once this is completed the tooth must be restored with a filling or more likely a crown or an onlay.
So after explaining to my patient that she could opt to save the tooth with root canal therapy she told me, “root canals don’t work on me.” When I asked her what she meant she told me, “I’ve had 3 or 4 root canals and I ended up losing each one of them. Why should I go through that again when I’m just going to lose the tooth?” Whoa! That’s a pretty serious claim! Do root canals “just not work” on some people?
Root canal therapy can fail for many reasons. Most root canal failures are due to one or more of the following 4 things:
chronic infection: You’re likely to have a better root canal therapy outcome if the tooth hasn’t been infected for a long time. Occasionally a tooth can be traumatized and not have any symptoms for years, even decades! Often these teeth will become darker than surrounding teeth even though there is no pain or swelling associated with the tooth. These teeth usually have a low grade, chronic infection. Treating teeth that have been infected for a long time is much less predictable than a tooth that was never infected.
missed anatomy: Unfortunately, root canal systems are complex and variable. It’s difficult to find all the pulp in a tooth and even more difficult to make sure it’s all removed. At Mead Family Dental we use a dental operating microscope for all root canal procedures. This helps us find as much of the pulp tissue as possible. However, sometimes we can’t find all of it and if we’ve missed some of the pulp tissue sometimes people have problems like pain and reinfection. This is relatively rare, but not unheard of.
restoring the tooth: We don’t do all of these procedures at our office. Often we’ll refer to a specialist called an endodontist who does only root canal therapy procedures. Usually when an endodontist finishes this procedure they’ll place a provisional (temporary) in the tooth. Since root canal therapy can cost upwards of $1000 per tooth, often times people would prefer to wait to do a conventional restoration like a bonded filling or crown. This is the mistake that is the primary cause of the “root canals don’t work” myth. Temporary fillings are just that. Temporary! If this short term filling washes out, the sealed space that the dentist just meticulously disinfected becomes infected by oral bacteria again.
reinforcing the tooth: Every dentist that treats these problems has to walk a tightrope. The hole that they open into the root canal space has to be big enough so that you can see what you need to see, yet small enough to remove as little tooth structure as possible. Sometimes this access requires the removal of so much tooth structure that the tooth becomes weakened. Teeth that have had root canal therapy are often best treated with a partial or full coverage restoration like an onlay or crown. These teeth should be treated as soon as possible after the root canal treatment, otherwise they are at great risk of fracture.
Root canal therapy is usually quite successful. I don’t believe that there’s a certain kind of person that just shouldn’t have root canal therapy. I do believe that there are some people that have had catastrophically bad luck with root canal therapy and other dental treatments, but I firmly believe an honest talk with a trusted dentist can help get to the bottom of past dental treatment failures. Understanding why we sometimes see bad outcomes with the treatment can help you decide if it’s right for you!
Did you find this post scary? Did it make you want to run out and have a root canal? I’d love to hear about it! You can share any Mead Family Dental post with a “Like” on Facebook, a “+1″ on Google+ or you can even “Tweet” it with Twitter! All you need to do is hover over the heart shaped button next to the title of the post. Or you can leave a comment by clicking on the balloon shaped icon next to the title.