A Cadaveric Study Using Computerised Tomography to Assess the Distribution of Iodinated Non-ionic Radiocontrast Agent after Periodontal Ligament Injection in the Horse

Background: Local anaesthetic injections into the periodontal ligament are used to desensitise structures to facilitate exodontia in human and equine patients. This technique has received little attention in the literature and therefore distribution patterns of local anaesthetic agents post-injection in equine patients are currently unknown. 

Objectives: This study aimed to assess the distribution of iodinated non-ionic radiocontrast agent injected into the periodontal ligament in the horse using computerised tomography (CT). 

Study design: Descriptive cadaveric. 

Methods: Five heads from equine cadavers (aged 6-20+) were positioned to simulate that of a live horse standing in stocks for a dental procedure. 2.2 ml of iodinated non-ionic radiocontrast agent (Omnipaque 300 mg I/ml) was injected into the periodontal ligament of both maxillary 09 teeth using a 27-gauge, 35 mm dental needle at four different sites (mesiobuccal, mesiopalatal, distobuccal and distopalatal). Immediately post injection the heads were imaged using CT. Images in the horizontal and vertical transverse planes, as well as 3D volume rendering reconstructions, were examined to assess the distribution of the contrast agent. 

Results: Three of five heads were successfully injected (six teeth in total) however only one head (two teeth) could be injected at the buccal injection sites. Three out of the six injected teeth showed favourable diffusion of the contrast agent, two of these teeth having been injected at all four locations. 

Main limitations: Small sample size. 

Conclusions: This injection technique is indicated to facilitate exodontia in equine patients. The unreliable diffusion seen here, however, would suggest that a combination with other perineural anaesthesia is recommended. The distribution of contrast seen in these three heads is suggestive that increasing age and presence of pathology are factors which increase success rate. 

Ethical animal research: Approved by the ethics committee of the School of Veterinary Medicine and Science, University of Nottingham. 

Informed consent: Owners gave consent for their animals’ inclusion in the study. 

Competing interests: None declared. 

Sources of funding: None.

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