Morphologic and Morphometric Description of the Temporomandibular Joint in the Domestic Dog Using Computed Tomography

The temporomandibular joint (TMJ) in the domestic dog is a synovial joint with 2 articular surfaces, the mandibular fossa of the squamous portion of the temporal bone and the articular head of the condylar process of the mandible. Although different diagnostic imaging techniques have been used to study the TMJ in dogs, morphologic and morphometric studies based on computed tomography (CT) are scarce. The purpose of the present study was to describe the morphologic and morphometric features of the TMJ in domestic dogs using CT. Width and depth of the mandibular fossa and 2 different angles between the mandibular fossa and the condylar process were measured in 96 TMJs of 48 dogs of different breeds (Labrador retriever, German shepherd, cocker spaniel, boxer, English bulldog, pug, shih tzu, and Cavalier King Charles spaniel). Temporomandibular joint conformation differed between breeds. Mid- and small-sized dogs had mandibular fossae that were more shallow, less developed retroarticular processes, and irregularly shaped condylar processes. The TMJs were more congruent in large dogs, presenting with deeper mandibular fossae, prominent retroarticular processes, and more uniform condylar processes. The measurements proposed in this study demonstrated 3 different morphologic conformations for the TMJ in the dogs of this study.