Dentistry Oblique Views

C. M. Isgren
N. B. Townsend (Corresponding author)
Philip Leverhulme Equine Hospital, University of Liverpool, UKEmail: nt8261@liv.ac.uk

Despite advancements in imaging, radiography remains the most used imaging technique for assessing apical infections in horse cheek teeth.
Good quality dental radiographs depend on:
- Radiographic technique
- Knowledge of normal anatomy
- Horse compliance
Interpretation of subtle pathologies can be challenging, particularly for experienced radiologists. Chronic cases tend to reveal dental abnormalities more readily.

Imaging is essential for diagnosing equine dental disorders, especially lesions that are not visible through oral examinations or endoscopy.
Radiography is the primary diagnostic method for equine practitioners, though alternatives exist like gamma scintigraphy and computed tomography.
The complex anatomy of the equine skull complicates radiographic interpretation.
Regular practice and an understanding of anatomy enhance outcomes in radiography of cheek teeth.
Recognizing common radiographic patterns of dental pathology is crucial for reading images.

Digital radiography (CR and direct radiography) improves image quality and personnel safety by reducing repeat exposures.
Use of modern, portable digital units is often sufficient, but a mounted stand can minimize movement blur.
Radiation safety practices include:
- Wearing lead aprons and gloves
- Using cassette holders with long handles to reduce exposure
Accurate head positioning is critical, and chemical restraint can aid cooperation and reduce repeats due to movement.
The use of a headstand is recommended for obtaining high-quality radiographs, with alternative options available if necessary.
Avoid metal head collars during sedation to prevent artefacts.
Hints for radiography:
- A grid is generally unnecessary for standing radiography due to low scatter levels.

Standard projections include:
- Lateral
- Lateral oblique (latero30° dorsal-lateroventral)
- Dorsoventral
- Contralateral oblique for comparison.
Additional methods may involve placing radiopaque markers for localizing pathology.

Position the horse with the affected side next to the plate, ensuring that the plate holder is vertical and close to the head.
The horizontal primary beam should be aligned with the horse's head's long axis, with careful collimation to minimize scatter.
Includes assessment of fluid lines or soft tissue opacities in the paranasal sinuses, but superimposition can limit localization of lesions.

Positioned similarly, the beam is directed at 30° from the dorsal plane.
Aims to highlight apices of maxillary cheek teeth while avoiding superimposition.
Requires precise beam adjustment to avoid distorted images of apices.

Increased exposure needed compared to previous views, directed at the midline of the skull, using careful collimation.
Evaluates nasal cavities and structures but can obscure specific areas with obliquity.

Similar procedure, targeting mandibular cheek teeth apices to avoid image distortion.
Features checking for draining tracts using probes where helpful.

Open-mouthed oblique projections highlight lesions on clinical crowns. Helpful tools include gags or tubing to keep mouth open.
Intraoral projections provide detailed views of the interdental bone and alveolar crest without superimposition from the contralateral side.

Key components: enamel, dentine, cementum, and surrounding bone; radiopacity varies with age and condition of the teeth
Proper detection of periodontal ligament is crucial for assessment.

Eruption sequence in horses and its implications for radiographic interpretation.
Distinctions in normal anatomy become evident with age, enabling understanding of lesions over time.

Understanding normal anatomy is critical for interpreting diagnostic images alongside clinical signs.
Common indications for dental radiography:
- Diagnosis of apical infection
- Severe periodontal disease
- Polydontia and other abnormalities
Sensitivity and specificity in identifying apical infections improve with experience and use of modern techniques.
Advanced imaging options include nuclear scintigraphy and computed tomography for unclear cases or concurrent conditions.

A comprehensive set of diagnostic images and anatomical knowledge are essential for diagnosing equine cheek tooth infections.
Radiography detects subtle changes associated with periapical infection effectively but with inherent limitations.

Reliable signs include periapical sclerosis and halo formation.
Some signs may lead to false positives or negatives affecting clinical diagnosis.

This article is a review of existing data; ethical review was deemed unnecessary as per institutional guidelines.