Your child just had “X-rays” taken at
the dentist last month. Why does the orthodontist need to take another one? In
fact, why do orthodontists need X-rays at all?
X-rays, officially called
radiographs, are images created when a beam of radiation passes through the
body and hits a sensor (or a piece of film in older machines) on the other
side. X-rays have the ability to create pictures revealing the differences in
the densities of the tissues through which they pass. The “shadows” cast on the
digital sensor or film allow doctors to see objects hidden by the skin and
bone. The most common X-rays taken by general dentists are called bitewings. In
a bitewing, the dentist gets a detailed picture of a small group of teeth that
reveals the health of the enamel, inner canals, and roots. Enamel and fillings
are dense and appear white in color on the radiograph. The bone around the
teeth, the root canals, and decay are less dense and therefore appear darker.
Dentists are trained to interpret the light and dark patterns so they can
distinguish normal tissues from abnormal ones.
X-rays are essential in orthodontics
for many reasons. First, orthodontists are also dentists and, although they are
focused on different things, they share the responsibility of identifying
pathologies if they are present. These include abscesses, tumors, and other
things that are not necessarily directly related to straightening the teeth.
Although rare, such pathologies are many times identified for the first time by
orthodontists and lives can be saved as patients are referred for treatment.
The second reason orthodontists take
X-rays is to help them diagnose and treat orthodontic problems. Orthodontic
X-rays focus more on the position and form of the teeth and jaws than on
individual teeth like bitewings. Orthodontists are especially interested in
missing, extra, impacted, or misplaced teeth, and short, long, or misshaped
roots. Problems with the jaws include bones that are too big, too small,
asymmetrical (off center), too far apart, too close together, or misshapen.
X-rays provide orthodontists with essential information that helps them
determine where problems exist and the best way to correct them. The size,
shape, and position of the teeth and bone in X-rays dictate if surgery or tooth
extraction will be necessary.
Orthodontists also take X-rays
during treatment so they can monitor how treatment is progressing. Not all
effects of orthodontic treatment are visible to the naked eye. Although very
rare, moving teeth in some individuals (about 2%) causes the roots to shorten.
Orthodontists must check for this during treatment so they can determine if and
how long tooth movement should continue. Sometimes orthodontists observe how
the teeth are moving to help them finalize the treatment plan. I prefer not to
remove permanent teeth if possible, so in many borderline crowding cases I will
begin to align the teeth just to see how the teeth and bone respond. If the
progress X-ray reveals that there is not enough bone to accommodate all of the
teeth, I can always have some removed along the way.
After treatment, a final X-ray is
taken to evaluate the outcome of treatment and make recommendations for other
necessary procedures (i.e. wisdom teeth). Ideally then, I take one radiograph
at the beginning of treatment, one after about six months, and one after the
braces come off. Each of these X-rays exposes a patient to less radiation than
they would receive taking a typical airplane flight. All dentists are taught to
use the ALARA principle (As Little As Reasonably Achievable) when it comes to
radiation. I am careful to take X-rays on my patients only when it is in their
best interest, and I assume that my colleagues also do the same.
We are now using faster equipment, more sensitive films and sensors, better collimation, lead aprons, thyroid collars, and digital equipment (which greatly reduces the need for retakes) than ever before. These improvements have resulted in a 60% reduction in radiation exposure since I got my license in 1999. Today’s patients receive the equivalent of only one additional day’s worth of background radiation (from the sun) each time they get a pano.
Doc W
Content used with permission by Dr. Greg Jorgensen
