Radiology: dental

Introduction

The bulk of the tooth (roots and most of the periodontium) can only be visualized by means of intra-oral radiographs.
Around 70% of dogs over 3 years have some form of dental disease and as much as 70% of the pathology in the mouth may go undetected without dental radiography.

Radiographic considerations

Fine detail screens are required.
Non-screen film (eg dental film size 4) or a small flexible cassette and screen is ideal for nasal chambers.
Radiography should be performed for any teeth showing pathology or suspected pathology after careful probing.
Full mouth radiographs are not commonly performed but are of benefit in dogs showing gingivostomatitis or requiring investigation of orofacial pain where a focus/ foci of pathology cannot be identified clinically/ on probing.
Ensure that adentulous areas (missing teeth) area imaged especially where signs of inflammation (eg gingivitis) are seen; root remnants are common!
Size 2 (periapical) film is ideal for most teeth. Canines and other teeth in large breeds may require size 4 (occlusal) dental film.
The number of films required for a full mouth series depends on the size of the dog but includes:
- Upper incisors, upper left canine (anterio-posterior oblique and lateral), upper right canine (anterio-posterior oblique and lateral), upper left maxillary premolars and molars, upper right premolars and molars, lower canines and incisors, lower right mandibular premolars and molars, lower left mandibular premolars and molars, lower left canine anterio-posterior oblique +/- lateral, lower right canine anterio-posterior oblique +/- lateral.
As technology advances many dentists and veterinary dentists have started using direct digital X-ray systems for intra-oral radiographs. A sensor is placed in the patient's mouth instead of an X-ray film and exposed . Both direct and indirect systems are available.
Direct digital: the image is transferred directly via the sensor to a computer. The advantages of using direct digital systems are that a much lower exposure is required and the time saved during procedures. The software package allows one to view and enhance images and provides images in more detail. Currently there are 3 systems available - Kodak, Eva and Schick. Disadvantages are the cost and size of sensor - only size 2 is available as yet. This size limitation means that larger teeth may require two views, each of a different tooth portion (usually coronal/crown then radicular/root areas), to enable full assessment. Despite this, the direct system offers the greatest benefit over traditional dental film and processing.
Indirect digital: the image is transferred via a digital accessing system from the sensor to a computer. The advantages of using indirect digital systems are that a much lower exposure is required and both film sizes 2 and 4 are available. The software package allows one to view and enhance images and provides images in more detail. Disadvantages are the cost of sensor renewal (its potential for scratches/ damage), sensor size limitation and slower image production compared to direct digital.

Restraint

Dental radiography requires general anesthesia. This is the only way to obtain accurate projections and avoid trauma to film, sensor or operator!

Indications

Some lesions may be detected clinically but the full extent of the lesion or disease can only be accurately assessed with radiographs.
Much pathology will be detectable only with radiography.
Accurate diagnosis, treatment planning and treatment monitoring requires examination of the whole tooth including root(s) and surrounding bone.