Abstract
Computed tomography (CT) has become a routine method to examine the equine skull. Its clinical use for the diagnosis of diseases of the incisors and canine teeth has not been reported so far. The goal of this study was to study the prevalence and relationship of single CT features and equine odontoclastic tooth resorption and hypercementosis (EOTRH) in equine incisors and canine teeth. In this descriptive retrospective study, helical CT studies of 115 warmblood horses of the age of 5 years or older examined between 2007 and 2020 for reasons unrelated to the incisors and canine teeth were included. Resorption in the crown or root, hypercementosis, widening of the periodontal space, clubbing of the root, lysis of the lamina dura, an abnormal pulp cavity and fracture of the root were recorded in all incisors and canine teeth. The length of the pulp cavity and the labial and lingual/palatal length of the enamel and root was measured in each incisor and canine tooth. Additionally, the angulation was assessed in each incisor. The variable EOTRH was defined based on the presence of resorptive lesions, hypercementosis and clubbing. In result median age of the included horses was 12 years (range, 5-29 years). With regard to the investigated population of horses, 44.3% of all horses had normal incisors whereas 55.7% of the horses had mild EOTRH changes in one incisor at least. Regarding the canine teeth, 54.7% of the horses had normal canine teeth whereas 43.3% horses had mild EOTRH in one canine tooth at least. With regard to all investigated teeth, 868 teeth (53.0%) were classified as normal, whereas 769 incisors and canine teeth (47.0%) showed at least one abnormal CT criterion. Clubbing of the root and hypercementosis were most common (37.1% and 22.7%, respectively) and EOTRH was present in 27.1% of all teeth. Mild changes were more common than moderate or severe abnormalities. In the lower jaw, hypercementosis and widening of the periodontal space at the anatomical root and apex of the root was significantly more frequent (p = 0.004 and 0.02), whereas clubbing of the root was more common in the upper jaw (p = 0.009). In canine teeth, resorption in the anatomical crown and anatomical root, widening of the periodontal space, clubbing and lysis of the lamina dura were significantly more common whereas hypercementosis was more common in incisors (p < 0.001). Frequency of certain CT changes significantly increased from central to middle and corner incisors. Severity of all single CT criteria as well as prevalence and severity of EOTRH significantly increased with age (r = 0.08-0.56). Linear forward and backward multivariate regression analysis confirmed a significant association between prevalence and severity of EOTRH and age, changes of the pulp cavity, widening of the periodontal space at the anatomical root and incisor group (central, middle, corner) (p = 0.01 - < 0.001). In conclusion computed tomographic changes of the incisors and canine teeth are common and age-related in warmblood horses. Therefore, treatment of EOTRH should not be based on diagnostic imaging alone, but always in combination with a thorough clinical examination.
Bearth, N D