Imaging Oral Pathology: from Examination to Computed Tomography

Diagnostic imaging is a critical tool for complete evaluation of oral health and disease in the horse. Even the most advanced oral exam using endoscopic techniques will not be able to determine the health of adjacent hard and soft tissue structures, the reserve crown, and the roots located within the alveolus. Some equine teeth that appear normal on examination of the clinical crown can be the cause of regional sinusitis, impressive apical pathology, and fistula formation. Diagnostic imaging can help identify the tooth/teeth responsible for current clinical signs as well as provide additional information regarding the health of otherwise clinically normal teeth. Many times incidental pathology can be identified during imaging studies allowing the veterinarian to diagnose the current problem and to warn the owner of developing pathology. The first step in evaluating any horse for dental pathology should be a complete oral examination. Over the past decades, advances in intraoral imaging have made the exam more fruitful. The introduction and emphasis on using a mirror to evaluate teeth intraorally was followed by suggestions for the use of an intraoral camera. Rigid endoscopes have proved most useful, and there are currently a handful of models to choose from on the market. A rigid endoscope detects subtle lesions on the tooth surface and in adjacent soft tissue that was previously invisible to the practitioner. It is also a valuable teaching tool for students and clients as they are able to view the pathology in real time for the veterinarian to point out lesions. This tool is highly recommended for any veterinarian commonly performing equine oral examinations. Radiology is widely used, and the combination of view variety (extraoral and intraoral) and improved imaging systems has led to a renaissance in the practitioner’s ability to diagnose pathology with this modality. With the appropriate tools, adequate views, and experienced eyes, the majority of dental cases can be diagnosed with a complete oral examination and dental radiography. When radiography is not enough, four additional modalities can be utilized to provide additional information. Ultrasound, nuclear scintigraphy, magnetic resonance imaging (MRI), and computed tomography (CT) have all been used as ancillary techniques to either confirm or complete a diagnosis. CT has proven to be the most valuable of these four modalities to identify maxillofacial pathology providing accurate images in cross sectional and multiplanar views. Both soft and hard tissue algorithms with or without contrast provide ample information. Three-dimensional reconstructions are particularly useful for maxillary and mandibular fracture repair. The equipment and facility expense for nuclear scintigraphy, CT, and MRI programs usually restrict clinics, hospitals, and universities to providing one or two out of the three aforementioned modalities. Therefore, these facilities have become quite good at using the