Dental X-Rays- Are they Dangerous?!!? Do I really need X-rays??

Written by on February 5, 2013 in Uncategorized

Hello Edmonds, Seattle, King and Snohomish counties,

I here today to chat about dental x rays, and the real skinny on radiation and what is and isn’t true concerning this media darling of a topic. First and foremost , before we go any further- YES!!!! Dental X- rays are needed and VERY important to both our oral health and our overall body health

DENTAL X-RAYS ( or radio-graphs)

How much did I get and how bad did it hurt?

Dental patients are subject to some risk when they have a dental x-ray
taken, but it is a very small one. An examination consisting of a few
radio-graphs adds radiation exposure comparable to a couple of weeks of
natural background radiation and results in an increased risk of cancer of
about 1 in a million. The risk is small because of efforts by the dental
community, manufacturers, and state radiation control programs to reduce
the exposure and carefully consider the need for each X Ray. The average patient takes approximately 4-8 per year. This amount has decreased approximately 75% from a decade ago when patients would have 16 + X rays per year- WOW ( pat on the back to the Department of Health!!)

Questions frequently asked by dental patients are “how much radiation am I
getting?’ and “how dangerous are these x-rays?” Patients are often annoyed
when they do not receive simple answers to what appear to be simple
questions; yet simple satisfactory answers are difficult to come by.

A simple answer to both questions would be that from each dental
radio-graph using FILM ( Complete Dentistry uses digital X-Rays -which is even less!!!), you receive about 300 millirads locally to the jaw,
and that increases your probability of cancer by less than 0.000001 in
your lifetime. While that answer is simple, it is not satisfying, since
most people do not have an intuitive understanding of ‘milliard’, the way
that they do the term ‘pound’ or ‘quart’, nor do people intuitively
understand risk probability.

One way to truthfully answer the question of “How much?” is to respond
“Not much.” Dental x-rays account for less than 10% of all medical and
dental radiation received by the U.S. population each year. That’s not
much, considering many more people get dental x-rays taken each year
than have medical x-Rays.

A second way to answer the question is to compare with other sources of
radiation. Consider a dental x-ray, a chest x-ray, an abdominal x-ray, and
natural background radiation, x- or gamma (Which are basically the same
despite the name difference, which reflects how they are generated, not
what they are).

Natural background radiation comes from trace amounts of
naturally-occurring radioactive materials externally in rocks, trees, and
minerals, from such sources within our own bodies, and from outer space
sources (Cosmic Rays). As humans, we have lived with this natural
radiation from birth and before. These x- and gamma radiations strike all
over our bodies and are absorbed by all tissues and organs, from bone to
liver to skin. We thus receive a “whole body dose”. Neglecting the
contribution of radon, the average individual in the U.S. absorbs
approximately 100 millirads of whole body radiation energy each year. The
term millirad is an amount of radiation absorbed per gram of body tissue.
The average amount of radiation absorbed daily from natural background
radiation is approximately 0.27 millirad per gram of body tissue, or 0.27
millirad whole body dose (100 millirad/365 days = 0.27 millirad per day).
Natural background may vary from one part of the U.S. to another by more
than 20% of this average value (or +73 days of average natural background
radiation excluding radon).

Radon is also a source of exposure from natural background radiation;
radon is a naturally-occurring, tasteless, odorless gas that exposes the
lung to alpha radiation. We have chosen to exclude radon form our
comparisons based on the difficulty of drawing comparisons between the
risks and dose from radon and those gamma-emitting sources. Others may
choose to include radon, and this inclusion will change the equivalent
number of background days of radiation that equals the whole body dose
equivalent from x-ray sources.

A chest radio-graph (x-ray) exposes only a fraction of the body. If one
takes the radiation energy absorbed by that part involved in the chest
radio-graph and spreads it over the whole body, one can calculate the whole
body dose equivalent for the chest radio-graph. The British Institute of
Physical Sciences in Medicine has done just that. They calculate that one
chest radio-graph results in a whole body dose equivalent of about 5
millirad, equal to about 18 days of average natural Background radiation.

An abdominal x-ray exposes a different fraction of the body. The whole
body dose equivalent for a typical abdominal radio-graph, as calculated by
the same source, is 80 millirad, equal to about 296 days of average
natural background radiation.

A single dental intraoral radiograph USING D-SPEED FILM results in a whole
body dose equivalent of about 3 millirad, or about 11 days of average
natural background radiation. But an intra-oral image is taken by a modern
direct digital system like Schick is only a third or a fourth of that, or
less than 1 millirad (or 3 days of natural background), which is what Complete Dentistry uses!!

These comparisons must be made with caution. Obviously, a dental
radiograph does not expose the same organs as an abdominal radiograph, and
the organs or tissues exposed differ in their sensitivity to radiation.
Still, as a yardstick, the comparisons are valuable.

The second question is “How dangerous are these x-rays?” Obviously, x-rays
are dangerous- they are carcinogenic and people die of cancer. Young
people are especially sensitive to the effects of x-rays. Approximately
one third of the population of the U.S. will develop some form of cancer
during their lifetime. Of course, not all of these people will die from
the cancer- many will be cured. Still, in a hypothetical U.S. population
of one million people, approximately 300,000 will contract cancer sometime
in their lives.

Studies indicate that the levels of exposure used in a typical dental
x-ray examinations will cause at most a one-in-a-million probability of
the individuals contracting cancer sometime during his/her lifetime. If
every person, therefore, in a population of one million were to have a
single dental x-ray examination, consisting of a few intraoral
radiographs, the incidence of cancer could rise from 300,000 to 300,001
persons (maximum estimate) out of that hypothetical population. It could
also remain at 300,000 (minimum estimate), with no observed increase of
cancer. Since the increase is so small, estimates are just that-
estimates. There is no certainty that an extra cancer will result.

Why are we interested in dental x-ray safety if the increased incidence of
cancer caused by dental x-rays is so low? First, if there are 250 million
people in the U.S., and if each one gets one dental x-ray examination
every year for years, we are then dealing with a possible eventual
increase of 250 cancers per year or a total of 12,500 cancers over a
50-year period; thus, on a U.S. population basis, the numbers, while
small, are worthy of our attention.

Second, the increase is low because there is continuing attention on the
part of the dental community, manufacturers, and state radiation control
programs to monitor and reduce exposure thus the risk of dental x-rays.
This has been done by reducing the exposure used for obtaining each
radiograph, by using good technique, and by carefully weighing the need
for each radiograph, factoring in the recommendations contained in the
brochure, “The selection of patients for X-Ray examinations: Radiograph
Dental Examinations”. Relaxation of this attention could result in a
significant increase in the risk to the population. We want to keep the
risk low for the population as well as the individuals involved.

In conclusion-necessary x rays ensure our gum health, show the dentist if there are cavities, and ensure our dental restorations are fitting properly and cavity free. Please feel free to visit Dr Etue and team at our office with any questions. You can also call or email too.

Until next time- Keep Flossing
Dr Ryan Etue, DMD @ Complete Dentistry

Now the foot notes , plus thanking the department of Health and the American Dental Association for data for this blog post
(1) I.P.S.M. Report #53, “Patient Dosimetry Techniques in Diagnostic
Radiology”, Institute of Physical Sciences in Medicine. London, 1988.
(2) The Report of the Panel to Develop Radiographic Selection Criteria for
Dental Patients, unpublished manuscript submitted to ADA. March 20, 1989.
(3) Committee on the Biological Effects of Ionizing Radiation: The Effects
on Population of exposure to Low Levels of Ionizing Radiation (BEIR V),
Washington, DC. The National Academy of Sciences.
(4) Practical Periodontics and Aesthetic Dentistry. The Journal Publishing
Group, 1989.
(5) Cancer Facts and Figures- 1990, American Cancer Society, Atlanta, GA.
(6) The Selection of Patients for X-Ray Examinations: Dental Radiographs
Examinations, HHS Publication FDA 88-8274.



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