Jan Bellows, DVM.
Diplomate, American Veterinary Dental College
All Pets Dental Clinic
(954)432-1111
9111 Taft St
Pembroke Pines, FL. 33024
INTRAORAL RADIOLOGY
Examining a dog's or cat's mouth has been compared to opening a Christmas
gift in that there is usually a surprise waiting, and unless you completely
unwrap the present you will never find out what it is. Dental radiology
allows the practitioner to further unwrap the mouth to "look inside" and
examine the tooth as well as the supporting structures below the
gum line.
At one time veterinary dentistry consisted of removing calculus from the
crown. Now, cleaning the crown is only part of the dental prophylaxis which
also includes using a probe to measure periodontal pocket depths, charting
abnormalities, polishing, and intraoral radiography.
When intraoral films should be used is an individual decision. In general,
any time the practitioner or staff notes a dental abnormality, or if there is
unexplained bleeding, a radiograph is indicated. Common examples include
evaluating the presence of unerupted teeth in show dogs (especially
Dobermans, Rottweilers, and Giant Schnauzers all which require at least 40
teeth to be shown); bleeding; determining treatment options for periodontal
disease; registering endodontic parameters including pretreatment;
intraoperative and postoperative care; evaluating the extension of oral
masses into the maxilla or mandible; and postoperative evaluation of
extraction sites for root fragments
Veterinary practitioners have the choice of using their stationary x-ray
machine, a portable unit or a human dental x-ray machine, The stationary unit
should he set at a 12-16 inch film focal distance. Suggested technique used
for cats and small dogs: 100ma, 50-70kvp, and 1/10 second. Human dental
nonscreened film is commonly used and is less cumbersome than bulky standard
veterinary film cassettes. Ultraspeed film sizes 0 ( 1/2" x 1"), 2 ( 1" x
2"), 4 ( 2" x 4" ) adequately serve in most practice situations. Size 0 is
especially useful for feline intraoral radiography. Ektaspeed film is twice
as fast as ultraspeed. The trade-off is less detail with the Ektaspeed
film.
Every intraoral film taken should include the full length of the tooth and at
least 2 mm of the periapical bone If there is pathology present, the entire
lesion should register on the film together with normal bone,
Patient positioning is critical to avoid distortion. The ideal dental
radiograph employs paralleling technique. The x-ray film is supported
parallel to the long axis of the tooth and the central x-ray beam is directed
at right angles to the tooth and film. This method limits geometric
distortion in order to give an accurate representation of size and shape of
the structures studied,
Anatomic configuration of the maxilla does not lend itself to use of the
parallel film x-ray beam positioning method. The bisecting-angle technique is
used here and in situations where the film cannot be placed parallel to the
tooth surface, The x-ray beam is aimed at right angles to an imaginary line
that bisects the angle made by the film and long axis of the tooth. Generally
a 45 degree angle from the plane of the hard palate is used in the maxilla.
When radiographing the anterior mandible in order to visualize roots of the
incisors and canines, the central beam should be aimed at a 20 degree angle
to the film plane.
There are several methods employed to develop intraoral films. Some
veterinarians use regular hand tank chemicals and timing, others attach the
films with photographic tape to a larger film and use the automatic
processor. There are also automatic processors for dental films. An easier
and faster (time to examination of diagnostic film-one minute) method is
using rapid-process developing and fixing solutions in the darkroom, or using
a Chairside Darkroom with the rapid-process chemicals, The Chairside Darkroom
has an added advantage of a safety filter glass top which lets the
practitioner develop the film at the dental operatory decreasing time spent
walking to the hospital darkroom. The intraoral radiographs are immersed in
the developer for ten to twenty seconds depending on the temperature and age
of chemicals, then immersed in a water rinse, placed In the fixer for at
least one minute, then rinsed once more in a new water solution. After
examination the film should sit for one hour to ensure adequate hardening of
the emulsion for a permanent record.
Intraoral radiology should be an integral part of every involved dental case
in every animal hospital. The ease of using standard stationary veterinary
radiograph machines, the ease or processing, and the great amount or
information gained make the dental x-ray a win-win-win proposition.