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.