16
E Q U I N E D E N T I S T RY — A N I N T R O D U C T I O N
The use of a bisecting angles technique will minimise elongation or shortening of images. The technique is simple
but often complex to describe. Essentially place the plate parallel with the horses face, then move the plate out
to where it is parallel with the end of the X-ray machine, now move it back to where it is halfway between these
two positions.
Latero 35-45º ventral latero dorsal oblique
This view is used to visualise the mandibular arcades, again a bisecting angle technique is used.
Open mouth lateral oblique
A wooden block, piece of PVC pipe or a suitable speculum is used to keep the patients mouth open. The open
mouth oblique views are used to examine the crowns of cheek teeth; these views are particularly useful for
assessing the impact of periodontal disease.
Dorso ventral offset mandible
This view requires placing two loops of rope around the horse’s premaxilla and mandible and applying pressure
to each to offset the jaw. A cassette is then positioned ventrally along the mandible. This view reduces
superimposition of the maxillary cheek teeth and allows for assessment of structures such as the nasal septum.
Problem solving
As previously mentioned, time taken to properly label images, care with correct positioning and developing an
exposure chart will eliminate many of the common problems. Another important point is to remove head halters
or collars from the field of interest (esp. those with metal buckles). The use of a large plate and coning the
primary beam to include the entire field of interest should also help in many instances.
Dental anatomy
The radiographic appearance of horses teeth varies significantly with age, due mainly to the hypsodont nature
of their teeth. Care needs to be taken when interpreting dental radiographs and knowledge of age appropriate
issues is important. For example the apical region of cheek teeth in a young horse (age 3-5) will vary markedly
between individual teeth and due to the development of eruption bumps (or cysts) normal anatomical changes
such as widening of the periodontal space at this age may mimic those seen with advanced dental pathology in
another age group of horses.
Practitioners should always radiograph the contralateral arcade and utilise it for comparison, the pulp horns of
teeth become more distinct as the horse ages and there begins to be more apical development. The periodontal
ligament is visible as a thin black line between the tooth and the alveolus, and disruption or widening of this
structure is often associated with dental disease
Additional radiographic techniques
The use of metallic markers such as paper clips, surgical staples and shoeing nails to identify areas of facial
swelling, can be useful when evaluating the relationship between such swellings and involvement of dental
structures. In cases where a sinus tract is present malleable metallic probes can be useful tools for examining
the depth and location of such tracts, as well as for confirming the location/involvement of affected teeth.
Contrast material ( such as Iohexol) can also be injected into these to provide further diagnostic information.