Investigation of the sensitivity and specificity of radiological signs for diagnosis of periapical infection of equine cheek teeth

Reasons for performing study: Radiography is commonly used for the diagnosis of equine cheek teeth (CT) infection but, to our knowledge, no study to date has evaluated the relative values of individual specific radiographic signs when making a diagnosis. Objectives: To investigate the sensitivity and specificity of individual radiographic signs identified from the literature for the diagnosis of CT apical infection using a retrospective case‐control study. Methods: Cropped radiographs taken using computed radiography of 41 apically infected CT and 41 control CT were independently blindly evaluated by 3 clinicians for the presence of 12 predetermined radiographic signs associated with CT apical infection. A final diagnosis of either noninfected or infected was made. Sensitivity and specificity were calculated for the presence or absence of each radiographic sign for each clinician. Uni‐ and multivariable conditional logistic regression were used to determine strength of association of the 12 radiographic signs with apical infection. Results: Median sensitivity and specificity for the diagnosis of CT apical infection were 76 and 90%, respectively. Periapical sclerosis, clubbing of one or 2 roots, degree of clubbing and periapical halo formation had the highest sensitivities (73–90%), with moderate specificity (61–63%). Multivariable conditional logistic regression revealed that severity of periapical sclerosis and extensive periapical halo were strongly associated with CT apical infection. Conclusions: The presence of periapical sclerosis and formation of a periapical halo were strongly associated with CT apical infection. Computed radiography appears to have a higher sensitivity but similar specificity to previously published results using film radiography to detect CT apical infection. Potential relevance: These findings may aid practitioners when interpreting radiographs of equine CT as to the relative significance of their findings.