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X-rays in Dentistry
Extremely Safe and Extremely
Important
By Dr. Jeff Shnall
Summary of
article:
Dental x-rays are an
important tool to help you keep your teeth. X-rays help
dentists reduce pain and suffering by detecting cavities early,
before they get to the stage of painful toothaches and are an
economical way of keeping your dental costs low.
Dental x-rays deliver a
small amount of radiation to our tissues compared to annual dose of
radiation we are exposed to from all other natural
sources.
A common unit of
measurement of radiation exposure is the millirem
(mRem).
The amount of cosmic and solar radiation,
as well as the natural radiation we are exposed to from our air,
water and soil (including radon gas) amounts to 360 mRem/yr or
about 1 mRem of radiation per day.
Regarding dental
x-rays, four x-rays contain 0.3 mRem of
radiation. Compare the number 0.3 to the 360mRem’s of
radiation you are exposed to simply by living on planet
earth. This is less than one tenth of one percent of your
annual radiation exposure. A full set of dental x-rays is 1.5 mRem which we
may take once every 5 years in selected
patients.
Introduction
It would be impossible to deliver high quality dental care that
our patients deserve and expect without dental x-rays. While
some procedures can be done without the aid of x-rays, the more
complex and comprehensive treatments that dentists provide would be
simply impossible without first taking x-rays of a patient’s teeth
or jaws.
Let us for a moment imagine what dental treatment would be
like if dental x-rays were not available to us:
- Children and adults would be
far more likely to need root canal treatment or extraction of teeth
that are too far gone for simple fillings.
- Tooth removal would not
be able to be safely performed without dental x-rays.
X-rays help us safely remove teeth without harming nearby
teeth and nerves. As well, some teeth have curved, twisted
roots or multiple roots that would make their removal much more
difficult if we attempted to treat them sight
unseen.
- root canal
treatment would not enjoy the high success rate that it enjoys
today without dental x-rays, as dentists would not have a clue of
how many canals are in a tooth to be treated nor their
length or shape. Proper root canal treatment would be quite
impossible without at least an initial x-ray to help us plan the
treatment.
- The success rate
of dental implants would plummet as x-rays are invaluable in the
planning and placement implants. For example, they tell us if
we have enough room to place an implant in a given
site.
- Gum disease would
often go undiagnosed and would be difficult to treat if we did not
have x-rays to give us a sense of the health status of the bone
that holds our teeth in.
I could on for pages about all the benefits of dental x-rays but
I won’t. Suffice it to say that our dental health would
deteriorate if we could not offer dental x-rays to our
patients. Images of Tibetan street dentistry come to
mind. That is an eye opening interesting internet search if
you haven’t seen how dentistry is sometimes unfortunately practiced
literally on the side walk in places like India and Tibet.
So the next question is how often are x-rays needed and
how many are needed?
Dentists are supposed to take the fewest x-rays as necessary for
the diagnosis and treatment of our patients.
Here a some brief guidelines that we use in our office.
For young children:
Sometimes the baby molars in the back of the mouth have a little
bit of spacing between them, allowing for visual cavity inspection
without the need for x-rays. There are times, however, that
for children as starting at about three years of age we do
try to take two x-rays once per year to check for cavities starting
in between the back teeth, if these teeth are
positioned close together.
As well, if a child is having a problem with a particular tooth
further x-rays to see the root area of the tooth will usually be
required.
For all other age groups:
This x-ray schedule is pretty much the same for all other age
groups: one x-ray per side in children, once yearly to check
for cavities between the back teeth, and one to two x-rays per side
in older teenagers and adults once per year. This will mean a total
of between two to four x-rays per year for a typical patient. These
x-rays, known as bitewings, also allow us to monitor bone levels
between the teeth as well and help detect defects in the bone that
occur when gum disease is present.
Additional x-rays may be required if there are any teeth
bothering the patient.
In patients in their mid to late teens we will often take
a Pandora x-ray, which is a large x-ray film that shows us the
upper and lower jaws and all of the teeth. This is often done
to allow us to see to check the position of the wisdom
teeth.
Sometimes it will be necessary to take a set of x-rays of all
the teeth in the mouth. This should be reserved only for
patients with extensive dental problems, such as widespread decay,
evidence of gum disease, for patients wanting certain dental
appliances or for patients who need extensive dental
treatment. Full sets of x-rays are normally not
necessary for a patient with a healthy set of teeth and gums who
just requires a routine check-up and cleaning.
So now we have some of background knowledge regarding why x-rays
are important and how often they are necessary. The next
question is they safe?
The thing about dental x-rays that concerns most patients is the
fact that they are a source of radiation. But is the amount of
radiation produced by dental x-rays a cause for concern?
To address this question I used information from the following
sources: articles from the Health Physics Society of the University
of Michigan, a fact book on radiation put out by The United States
Environmental Protection Agency as well as articles from the Mayo
Clinic and the American Dental Association. Links to these
articles are in my show notes for this episode. You can find
the links by clicking dentalhealthpodcast.com
Here are some facts about x-rays and
radiation:
Our world is a radioactive place to live and it always has
been. We are exposed to many sources of natural
radiation on a daily basis. This is because the ground we
walk on, the air we breathe, the water we drink and the soil in
which we grow our food contain radioactive particles
that give off radiation.
Examples of these natural radioactive particles are:
certain forms of uranium, thorium, radium and even some forms of
potassium.
According to physicists these
radioactive particles were created during the formation of our
universe and as well during the formation of our planet.
In addition, we are exposed to cosmic radiation from both the
sun’s rays as well as from high speed radioactive particles that
originate from outside of our solar system.
Because radioactive particles, also known as radionucleotides
are naturally occurring in our water and food, we digest these
particles and they become part of the tissues of our body, so to a
small extent our bodies are literally radioactive.
The largest single source of radiation that we are exposed to
comes from radon, which is a colorless, odorless gas that is
produced by the natural breakdown or decay of the element
radium. Radium is found in trace amounts in almost all rocks
and soil. Radon gas passes from the ground up into
houses and buildings through small openings small in floors or
walls. Some geographic areas have higher amounts of radon gas
production and this gas can become a health hazard if it reaches
high levels in homes or buildings.
Many building materials such as granite, cement, and drywall
also contain measurable amounts of radioactive particles of
uranium, thorium and potassium and thus are a source of
radiation.
X-rays are a man made source of radiation and are used
for diagnosis and therapies in medicine, for instance in radiation
treatment and in nuclear medicine.
In high amounts, radiation can have significant effects on our
bodies.
High doses of radiation can cause cell damage or cell
death. Damaged cells can be affected temporarily or
permanently.
The amount of cell damage depends on
the how much energy is absorbed by our tissues, over what period of
time and which organ is exposed.
Large doses of radiation can damage the
genetic material in our cells and can cause cancer and as well can
cause birth defects to occur in newborns.
However as we will see in a moment, the dose or amount of
radiation in dental x-rays is extremely small and is barely
noticeable compared to your daily or yearly dose of radiation from
all the sources we mentioned above. Let’s have a closer look
at this.
A common unit of measurement of radiation exposure is the
millirem (mRem).
The amount of cosmic
and solar radiation, as well as the natural radiation we are
exposed to from our air, water and soil (including radon gas)
amounts to 360 mRem/yr
or about 1 mRem of radiation per day.
Regarding dental x-rays,
four x-rays contain 0.3 mRem of
radiation. Compare the number 0.3 to the 360mRem’s of
radiation you are exposed to simply by living on planet
earth. This is less than one tenth of one percent of your
annual radiation exposure.
This is equal to the amount of natural radiation exposure you
receive in half of a day, from the sun, cosmic radiation and the
bricks of your house.
A full set of dental x-rays is 1.5 mRem which we may
take once every 5 years in selected patients.
A typical chest x-ray is 4 mRem.
Your yearly dose of radiation from your dentist, although
already low, can be reduced if your dentist uses fast exposure
x-ray film, takes quick x-rays settings and uses a lead apron with
a thyroid collars. In Canada dental offices must have their
x-ray equipment tested regularly to ensure it is performing
properly.
In conclusion, dental x-rays deliver a small amount of radiation
to our tissues compared to annual dose of radiation we are exposed
to from all other natural sources.
Dental x-rays are an important tool to help you keep your
teeth. X-rays help dentists reduce pain and suffering by
detecting cavities early, before they get to the stage of painful
toothaches and are an economical way of keeping your dental costs
low. A small filling is less expensive to place than a large
filling or a root canal that will be more likely to be needed if
you don’t catch cavities before they become big.
Annual x-rays will also allow the
earlier detection of gum disease and help prevent tooth
loss.
Dental x-rays help maintain healthy teeth and gums which is
important in maintaining your overall health. For example, an
adequate number of teeth to chew with are important in helping you
maintain a healthy diet. Patients who lose teeth
unnecessarily may have a more difficult time chewing coarser foods
such as whole grain breads and raw vegetables and opt for a softer
diet, which can lead to a diet lower in fibre. This in turn
can lead to higher incidence of colon cancer and other health
issues.
If you really want to maintain or
improve your health don’t skip necessary dental x-rays.
Instead, maintain a proper diet and get some daily exercise.
A brisk daily 30 to 45 minute walk is all you need and very few
people do this. This will serve you very well.
One side note I thought I would make on this topic has to do
with how often dental x-rays should be taken. One of the
articles listed in the reference section states that for adults who
have a low cavity risk, diagnostic x-rays can be taken once every
three years instead of once a year. This is not a view
held by many in the profession and I think for good
reason. Consider the following: The mouth is a very
harsh environment. I cannot think of another part of our body
that can deteriorate as quickly as our teeth. Sometimes
a patient who rarely gets cavities can start to experience a cavity
problem. Here are two examples of when this can happen:
If your mouth becomes dry due to an undiagnosed illness
such as diabetes or due to the side effect of a new medication you
may be taking, and you start to suck on candies to keep the mouth
moist you may start to get cavities. Or if you
start drinking a few cans of pop a day while at work or while
watching television at night you also may start developing
cavities. Not all patients are forthcoming about
changes in their diet or lifestyle and in these previously
cavity-free patients, waiting three years between taking four low
dose x-rays to check for cavities can mean the unnecessary loss of
teeth. In these two situations x-rays will
pick up the start of these cavities in between the back teeth
that cannot be seen visually and help us catch the cavities while
their small, and help dentists make an earlier intervention
re undiagnosed illness or correcting eating habits which can
be disastrous for your teeth.
References Used and Further
Reading:
The following are good sources
of additional information on this topic. If you are online
you can cut and paste the links below in to your search engine to
view them.
- Radioactivity in Nature.
The Health Physics Society, University Of Michigan,
2005.
http://www.umich.edu/~radinfo/introduction/natural.htm
- The use of dental radiographs,
Update and recommendations.
American Dental Association
Council on Scientific Affairs, JADA, Vol. 137, September 2006
.http://jada.ada.org/cgi/content/full/137/9/1304
- Radiation: Risks and
Realities, United States
Environmental Protection
Agency, May 2007
http://www.epa.gov/rpdweb00/docs/402-k-07-006.pdf
• Oral Health
Topics: X-Rays (Radiography), American Dental
Association, 2011.
file:///C:/Documents%20and%20Settings/Dell/Desktop/XRAY%20ARTICLES/ADA%20xrays.pt.htm
• Ionizing
Radiation: Fact Book, United States
Environmental Protection
Agency, May
2007http://www.epa.gov/radiation/docs/402-f-06-061.pdf
Radiation Exposure During
Imaging Exams, Mayo Clinic , Patient Education Article, 2009
Scottsdale Arizona, USA.
http://ndc.mayo.edu/mayo/research/ctcic/upload/radiation-exposure-during-imaging-exams.pdf
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