“Al, I’ve seen the phrase ‘levels of radiation that are so small as to be insignificant’ used a fair bit in the last few years. Particularly in relation to the Japanese disaster and the observation of levels of radiation around the world due to it…I think it would be instructive to have hard numbers to compare to background and other common sources that are considered safe.”
I agree. I’ve been explaining how safe x-rays are to patients for so long, I’ve kind of forgotten about the actual amounts of radiation that we expose them to. So let’s talk a little bit about radiation.
Electromagnetic radiation like visible light and x-rays travels in waves. And I have a cool graphic of it.
Electromagnetic radiation, or EMR, is any form of energy that travels in a wave. Visible light, radio waves, microwaves and x-rays are all forms of EMR that are common to us. The different types of EMR are characterized by their wavelength and frequency. Longer wavelength radiation like radio waves and have a lower frequency and are considered “low energy.” The shorter the wavelength the higher the frequency of the energy and generally these are “higher energy.” Very high energy like x-rays and gamma rays that can cause an electron to break away from an atom are considered ionizing radiation. These are the kinds of radiation that can cause health problems. Too much ionizing radiation can cause damage to the DNA in a person’s cells, which can lead to tumor formation and even cancer. The high energy state of x-rays is also what makes them so useful for seeing structures inside the body. Visible light is stopped by the skin and soft tissues around your bones and teeth, but x-rays can penetrate through them to show us things that we cannot see with visible light alone.
Harm from radiation sources is “dose dependent,” which means that more is worse. So in order to maintain safe levels of radiation in the dental office we need to know what kind of dose that we’re giving. The dose of radiation is measured in millirems or mrem. You can actually calculate common radiation doses using this chart from the American Nuclear Society.
So what is a “safe” level of radiation dosage? According to the American Nuclear Society the average level of radiation per person in the United States is 620 mrem/year. The safe allowable dose for people that are exposed to radiation in their work (nuclear plant workers, radiology technicians) is 5000 mrem/year.
Here are some examples of radiation dosages for different common exposures:
1 bitewing or PA dental x-ray: 0.5 mrem
2 hours in a jet plane: 1 mrem
1 panoramic dental x-ray: ~3 mrem
living in a stone, adobe or concrete house (instead of wood frame): 7 mrem/year
a full mouth set of dental x-rays: 9 mrem
chest x-ray: 10 mrem
1 pack of cigarettes each day: 36 mrem/year
chest CT scan: 700 mrem
whole body CT scan: 1000 mrem
These numbers reflect conventional film x-rays. Many dentists use digital x-ray technology which needs significantly less radiation to make x-ray images. In some cases the amount of radiation needed is 80% less than conventional film radiography, which would yield even lower radiation doses.
How much is too much?
Even though dental x-rays have an incredibly low dose of radiation, it makes sense to limit the amount of radiation as much as possible. Patients with a proven track record of low decay rate are an example of a type of patient that may not need diagnostic x-rays each year. Other diagnostic methods like high magnification with intense lighting, evaluating saliva flow and dietary evaluation can help determine a patient’s risk for new decay. For patients who have experienced cavities recently or new patients that don’t have a track record with their dentist, taking dental x-rays on a regular basis is necessary diagnostic tool.
So what’s a patient to do? How do you know if an x-ray is necessary? You need to ask your dentist. And if you don’t feel like your dentist is hearing you, perhaps you need to find another. Having a relationship with a dentist whose opinion you trust is a great way to know that you’ve found a good balance between too many x-rays and not enough information to prevent dental problems.
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A new study attempting to correlate dental x-rays in the past to an uncommon benign brain tumor was published today. And the headlines are scary! A cursory Google search of todays news yields these headlines:
“Are Dental X-rays Causing Brain Tumors?” (reported by KGO-AM)
“American Cancer Society study links dental x-rays to tumor” (reported by ABC Action News)
“Dental x-rays linked to common brain tumor” (reported by Reuters)
Early Dental X-rays Linked to Brain Tumors” (reported byABC News)
You get the picture. If you read the headlines and listen to the superficial news story you could walk away with the message that “dental x-rays cause cancer” or more likely “dental x-rays = bad” and “avoid dental x-rays.”
I am a dentist. I use digital x-rays to help me diagnose dental problems all day long. I really don’t want to think that all these x-rays I’ve taken over the years are causing horrible things to happen to my patients. I think it’s worth taking a good hard look at how the research was done and what it really says.
studying “past exposure”: The newly published study deals with past exposure of x-rays. Current standards for film x-rays use much less radiation than past standards. Digital x-rays use much, much less than current film x-rays. So any findings of this research only deals with your exposure in much earlier life. Technology has essentially solved the problem of higher exposure to dental x-rays already.
Do you remember?
using patient’s memories: The new study is a case control study. Case controls are useful, but are one of the weaker forms of medical evidence out there. The study compared two groups. One group was composed of patients who have already been diagnosed with a meningioma and the other group of patients did not have the condition*. The researchers asked the patients in the study to remember how often and what kind of dental x-rays they had in the past. So the data for the study was dependent on what the patients remembered. Can you tell me what kind of x-rays you had in 1995? Can you tell me whether a panoramic x-ray was taken instead of a full mouth set of x-rays? I’m not critical of the study being done nor of the researchers. That is how case control studies are done. I’m much more critical of how the media is portraying this evidence.
type of tumor: A meningioma is a “benign”/rarely cancerous tumor. It is the most common brain tumor. Meningiomas are tumors that occur in the membranes lining the brain and spinal cord. They can range in severity from occult (the patient didn’t know that they had the tumor) to life threatening. Common complications are seizures, localized neurological problems (muscle spasms) and they can cause increased intracranial pressure. Depending on their location they can “crowd out” vital structures of the head and neck. More severe meningiomas often require surgery, and sometimes radiation therapy. The cause of this type of tumor is not well understood, although there is evidence that genetics plays a part. The current study was done in an effort to understand potential causes. I don’t mean to downplay the seriousness of a meningioma. Since I originally wrote this blog post I have heard from many survivors of meningioma and they assured me that I definitely had downplayed their severity, and for that assumption, I apologize. The most severe type can be debilitating and even life threatening. Luckily, the majority are not this serious. The bottom line…dental x-rays don’t cause cancer, they don’t cause brain tumors and this research doesn’t claim that they do.
“is linked to”: The media loves to make the connection that “A is linked to B.” It makes great headlines. But it almost never means what the media portrays it to mean. “Is linked to” is not the same as “is caused by.” “Is linked to” or “is correlated with” only means that there is a relationship between the two factors. The new research shows that there is a relationship, but it’s not reasonable to assume that one causes the other, yet. More research will be done that may help us refine our understanding of these relationships, but until then…don’t assume!
So, should you have a talk with your dentist about x-rays? Absolutely! Should you avoid them at all costs? No. Not at all. The amount of radiation used with digital x-rays is so small as to be considered insignificant. The amount of radiation from dental x-rays is surprisingly low relative to some other common exposures…you might be surprised! Treatment or lack of treatment should be based on the amount of risk that the treatment can cause. A frank discussion with your dentist should help you understand that modern dental x-rays, particularly digital x-rays, are a very low risk diagnostic tool that offer great preventive benefit.
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* Actually, the group was assumed to not have a meningioma…the researchers took the patient’s self reporting of no meningioma as the same as “no disease.” Since often the condition displays no symptoms, this isn’t a good way to choose a control group.
We’ve had TV’s in the operatories of my office for years. Like almost a decade. Until 2011 the TV’s were limited to the reception area and my two operatories. If you wanted to watch TV, you had to be seeing me, not having your teeth cleaned. Last year, that changed.
More painful than having work done at Mead Family Dental
I got my teeth cleaned about a month ago while watching TV. I switched from “The Talk” to CNN. I pretty much watched presidential politics for the better part of an hour while Kelly cleaned my teeth. Although watching presidential politics is pretty painful, the cleaning was not. And the experience was pretty dang cool. I was distracted from what Kelly was doing in a really nice way. Except for having to watch Newt Gingrich.
In case you’re wondering, we have other channels besides CNN, Fox News or MSNBC. You can watch soaps, ESPN or Spongebob. Whatever you like. The point is to distract you from having your teeth worked on. Not that we plan on it being uncomfortable. In fact, we’re pretty proud of how comfortable treatment is at our office. But if you can watch your favorite TV show while someone lovingly crafts an exquisite, custom made dental restoration or carefully and painlessly cleans ever nook and cranny of your teeth and gums, why wouldn’t you?
Do you want to try this novel approach to dental care/television viewing? Call us at (989) 799-9133 or make an appointment online! We’d love to be your Saginaw dentist!
You brush your teeth to get the plaque off of them, right? And if you remove the plaque then you won’t get cavities, right?
The model dentistry has been explaining to patients forever is that plaque causes cavities and that if you can just remove the plaque then you’ll have healthy teeth. Unfortunately, it’s really not that simple.
Unless you’ve just had your teeth cleaned, like 2 minutes ago, your teeth are actually covered in a biofilm. It happens if you brush three times a day and floss like a maniac or if you haven’t seen a toothbrush in years. Biofilms form on most any surface that’s wet. Slime on the hull of a boat, coated rocks in a stream and the plaque covered surface of teeth are all examples of a biofilm.
Biofilms are actually microscopic communities of bacteria and the slimy matrix they make to stick to surfaces. A biofilm will “mature” over time and then spread. The plaque that dentists and hygienists talk about is actually a biofilm that’s large enough to be seen with the naked eye. Dental plaque/biofilm is actually made up of many types of bacteria. Some of the bacteria (Streptococcus mutans, for instance) found in this biofilm are the bad guys that can eat sugar and turn it into acid which can then cause tooth decay. Other bacteria (Streptococcus sanguinis) found in the plaque are actually known to make the biofilm less hospitable to the acid loving bacteria. So it doesn’t necessarily follow that biofilm = cavities. Someone who does a good job of brushing and flossing will generally keep the size of the biofilm smaller and potentially makes the biofilm “healthier” by increasing the % of bugs that don’t produce acid.
less beautiful and more common biofilm
O.K. Doc…I’m following you. Not all plaque is bad plaque. So why can’t they get rid of the bad bugs and leave the good bugs? Well, I’m glad you asked! There was a preliminary study out of UCLA about a mouth rinse that can do just that! Since it’s a preliminary study that means that real clinical trials to prove efficacy haven’t been done. They have some promising results on a small group of patients treated with a mouth rinse that can supposedly target S mutans (the bad bugs) in the plaque. According to one article there will be clinical trials starting in 2012.
If you like this post, 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.
If you’re looking for a dentist in Saginaw, we’re always happy to accept new patients! You can request an appointment online or call the office at (989) 799-9133. And, as always, you can email me at firstname.lastname@example.org. I always answer my own emails!
Sorry for no blogging so far this week. I've been busy preparing to testify before a Michigan senate committee on three bills that will benefit dentists and patients in Michigan!
senate bill 213: This bill would correct a loophole in the law that doesn't allow pharmacies to fill out of state prescriptions from dentists. Why is this important? Think or a patient living in the western Upper Peninsula who sees a dentist in Wisconsin.
House Bill 4389: This bill would give retired dentists and podiatrists special immunity when working on indigent populations. This would allow retired dentists to work without having to purchase malpractice insurance. This is the same immunity that physicians currently have.
Why am I doing this? My experience with testifying before a Michigan house committee was really good. I feel strongly that this potential legislation is very positive. Having a practicing dentist speak about how the laws will affect patients and dentists in the state of Michigan lets these legislators see why the legislation is important. SOMEONE should let them know…why not me? Another dentist colleague of mine is going to be testifiying as well. I appreciate that Dr. Tom Poirier is coming too!
Stay tuned for more blogs! I have some pretty amazing things that I'm working. I can't wait to show them to you!
Now this isn't something you get to do every day! This Saginaw dentist had the opportunity to testify before the Michigan House Health Policy committee! This is a cross posting from another blog I maintain at www.mapsinformation.com.
House Bill 4192 is a proposition to change MAPS to allow for participating prescribers to request a report of their own controlled substance prescriptions. This would allow for a prescriber to audit his patient records against all of the controlled substance prescriptions dispensed under their name. This would allow a practitioner to make sure no fraudulent prescriptions were being written under their name.
Several states including Colorado and Tennessee already allow this in the prescription drug monitoring program and the feedback that I've gotten is that it works great and has no discernible down side.
I was asked by the Michigan Dental Association to testify before the Michigan House Health Policy Committee. This was a pretty amazing experience! I sat in front of a microphone in a hearing room with Grace DeShaw-Wilner of the MDA and we explained to the committee why this legislation is a good thing for Michigan. There were several questions asked and we answered them pretty well, I think. The chair of the committee told us that she expected a committee vote by next week.
It was interesting to see how government really works. I'm pretty confident that the House will support the bill, but I will keep you posted here!