Background: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful disorder primarily affecting the incisor teeth of horses over 15 years of age. Clinical signs of the disease include mastication problems, halitosis and weight loss. The disease predominately affects the reserve crown and presents as a loss of dental tissue and excessive build-up of cementum. Objectives: Determine the radiographic scores of horses with EOTRH and age-matched controls. Increase understanding of EOTRH using microCT to compare teeth from horses with EOTRH and age matched controls. Methods: This study used radiography ( in vivo) and microcomputed tomography (microCT) ( ex vivo) to help understand and characterise EOTRH. For radiography, 87 patients were assessed using a radiographic scoring system for EOTRH. The microCT study was undertaken on 20 incisor teeth which were scanned and segmented to measure the different dental tissues. These were assessed using a descriptive analysis (surface roughening, tooth resorption, root blunting, pulp cavity). Study design: In vivo and ex vivo studies. Results: Radiographic scoring demonstrated that 03s were more severely affected than 01s in EOTRH. Total radiographic score and age had a weak positive correlation. Following microCT, we identified that EOTRH teeth had a lower pulp and enamel volume and therefore significantly higher ratios relative to the whole tooth volume, compared to control teeth. Cementum and dentine volumes were more variable in EOTRH teeth. Thus, their ratios relative to the whole tooth volume were not different to control teeth. Main limitations: The number of horses was relatively small. Conclusions: Results suggest differing degrees of tooth resorption and hypercementosis, potentially indicating multiple phenotypes of the disease.