The association between oral examination findings and computed tomographic appearance of the equine temporomandibular joint.

BACKGROUND: The temporomandibular joint (TMJ) forms the junction between the maxilla and mandible. Movement of the jaw and resulting masticatory forces have been extensively studied in the horse; however, less is known about the inter-relationship between this joint and oral and dental pathology. OBJECTIVES: To determine the association between specific oral and dental pathologies and anatomical variations of the TMJ imaged with computed tomography (CT) in horses with asymptomatic TMJs. STUDY DESIGN: Retrospective cross-sectional study. METHODS: Horses (n = 201) from three practices with a complete oral examination and skull or upper cervical CT study were reviewed. Age, breed, sex, clinical presentation, oral examination findings, slice width and practice were recorded. Alterations in contour and density of the mandibular condyle, mandibular fossa and intra-articular disc were also documented. Logistic regression, corrected for clustering by practice, was used to determine whether CT anatomical variations were significantly associated with the oral examination findings. RESULTS: Horses categorised as having abnormal TMJs were older than those with normal TMJ. Horses with periodontal disease were less likely to have abnormal TMJ findings compared with horses with no oral pathology. In contrast, horses with infundibular disease were more likely to have TMJ abnormalities. MAIN LIMITATIONS: Due to the cross-sectional nature of the study, it was difficult to establish whether oral pathology preceded TMJ abnormalities. CONCLUSIONS: Despite examining over 200 horses of varying ages, the biological significance of the observed associations between oral, or dental disease and anatomically appreciable temporomandibular joint disorders remains uncertain.

Mandibular osteopathy in a Hagerman horse, Equus simplicidens (Equidae, Mammalia), from Hagerman Fossil Beds National Monument (Idaho, USA).

Multimodality imaging, including computed tomography (CT) and digital radiography, was utilized to examine a fossilized hemimandible of a probable female Hagerman horse (Equus simplicidens) with a large, ventrally located, osseous deformation. Utilizing comparative pathology to the modern day horse, it was determined that the most likely etiology of the pathologic bony swelling along the ventral hemimandible was abnormal tooth development that led to chronic osteomyelitis and subsequent osseous proliferation, sclerosis and deformation.

Equine Odontoclastic Tooth Resorption and Hypercementosis: Histopathologic Features.

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a painful progressive condition of older horses that involves multiple teeth, including canines and incisors. EOTRH is uncommonly recognized by veterinary pathologists and in some cases may be misdiagnosed as cementoblastoma. The cause is unknown. The goals of this study were to describe the histopathologic features of EOTRH in 17 affected horses from the United States and to increase awareness of this condition. Samples ranged from affected tooth to the entire rostral mandible and maxilla. Affected teeth exhibited cemental hyperplasia and lysis. The marked proliferation of cementum in severe cases caused bulbous enlargement of the intra-alveolar portions of affected teeth. Several teeth contained necrotic debris, bacteria, and plant material in the regions of cemental lysis. All horses exhibited dentinal lysis in at least affected tooth, and several contained necrotic debris in these regions. Endodontic disease was often present with inflammation, lysis, necrotic debris, fibrosis, and/or a thin rim of atubular mineralized tissue in the pulp cavity. Periodontal disease was a common feature that was primarily characterized by moderate lymphoplasmacytic inflammation. Resorption with secondary hypercementosis appears to begin on the external surface of the teeth rather than within the pulp cavity. Distinguishing EOTRH from other diseases requires a complete history that includes the number and location of affected teeth, a gross description of regional hard/soft tissue health, and radiographic findings.