SAEVA Proceedings 2014 Dental Wetlab | Page 15

14 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 How to take dental radiographs of the horse Introduction This article aims to assist any veterinary practitioner to feel comfortable taking dental radiographs in the horse. The techniques described are relatively easy to perform in the field without specialised equipment and when used correctly can provide good quality images for diagnostic workups or case referral. With dental disease being one of the most common conditions affecting the horse, radiographs are of increasing importance in accurately determining the cause of disease and the likely outcomes for the patient. Equipment Any X-ray machine capable of 80kv is suitable for dental x-rays in the horse. Portable machines allow easy rotation and positioning and the ability to take images in the field. Good quality images are possible with film, computed radiography and digital radiography, however when using film it is vital that the film used is matched to the screen in the X-ray cassette. With CR and DR careful selection of software and time spent with the supplier will yield better results as there is wide variation in the appropriateness of standard algorithms when they are used to take dental X-rays. It is really important to spend some time developing a factor chart for the specific equipment used in the practice and to label all images correctly. As a practitioner receiving images from other veterinarians seeking assistance with interpretation, the three most common errors with the images I receive are unlabelled or incompletely labelled images, poor positioning and incorrect exposure. Therefore dramatic improvements in the diagnostic quality of dental images (particularly for referral) are often possible by simply Technique Proper restraint, sedation, patient support and positioning will provide both ambulatory and hospital based practitioners with good quality dental radiographs. Patients can be radiographed both in and out of a crush however bars and gates on the crush may sometimes interfere with positioning. Patients need to be adequately sedated and adequate sedation is heavy sedation eg Detomidine HCL 0.01mg/kg and Butorphanol tartrate 0.01mg/kg. Several landmarks should be used by practitioners to assist with positioning these include the facial crest and the intersection of the mandibular and maxillary cheek teeth Some form of head/chin support is required to prevent horses from moving their heads up and down, and a table, feed bin or “Wheelie bin” are good options. If using a crush with an extendable head support a dental halter can also be used, however some of these halters contain metal bars so care must be taken with positioning to avoid artefacts. There are a number of methods for holding and positioning X-ray cassettes, commercially available cassette holders provide an external framework and a long extension arm. These offer the benefit of decreasing radiation exposure to assistants, however the weight of the cassette on the end of the long extension or handle can make them tiring or cumbersome, they also usually only allow the use of a single size of plate. Some practitioners advocate the use of elastic straps or bungee cords to attach the plate directly to the patient, this has the advantage of eliminating the need for an assistant however it raises issues associated with the use of elastic straps and metal hooks under tension. The author prefers to use broad lipped “vise grips” with or without an extension handle. This allows more control over the orientation of the plate while not inducing the same fatigue as the commercially available holders; it does however require the use of an assistant. Due to the levels of sedation often required to obtain good quality images, it may also be necessary for the practitioner and or assistant to support or position the patients head to avoid axial rotation. Placement of a wooden block between the upper and lower incisors allows the practioner to take open mouth oblique views and may also assist with allowing the horses muzzle to rest comfortably on the head support.