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.

Morphometry and Morphology of the Articular Surfaces of the Medial Region of the Temporomandibular Joint in the Felis Catus (Domestic cat) - A Cone Beam Computed Tomography Study.

The articular surfaces of the temporomandibular joint (TMJ) in the cat consist of the articular head of the condylar process of the ramus of the mandible and the mandibular fossa of the petrous part of the temporal bone. Anatomic conformation of the TMJ articular surfaces can vary; however, this has not been studied in the cat. Thus, the aim of this study was to characterize the conformation of the medial region of the TMJ in mesocephalic adult cats as well as to determine the articular relationship by measurement of the degree of coverage of the mandibular fossa over the articular head. This was accomplished by assessing 60 TMJs from 30 mesocephalic adult cats by means of cone-beam computed tomography (CBCT). The width and depth of the mandibular fossa, and the degree of coverage of the mandibular fossa were evaluated using parasagittal reconstructions of the medial aspect of the TMJ by two observers. No statistically significant difference was observed during the intra and interobserver evaluation of the mandibular fossa width and depth and the degree of coverage of the mandibular fossa over the articular head. P-values for the studied variables were greater than 0.05. The resulting measurements demonstrated a concave mandibular fossa with a prominent retroarticular process and a poorly developed articular eminence; a well-defined rounded articular surface, and a high degree of coverage (171°) of the mandibular fossa over the articular head. In conclusion, the articular surfaces at the medial aspect of the TMJ displayed elevated geometric similarity, with an articular head of the condylar process deeply seated in the mandibular fossa.

Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study.

OBJECTIVES: Temporomandibular joint ankylosis (TMJA) is the partial or complete inability to open the mouth due to intra- or extra-articular fibrous, bony or fibro-osseous tissue proliferation. Surgical procedures such as gap arthroplasty, condylectomy or wide extra-articular osteotomy have been recommended to treat this condition; these techniques are challenging, time-consuming and have been occasionally associated with postoperative recurrence, severe periarticular neurovascular iatrogenic trauma and death. Segmental mandibulectomy had previously been recommended as an alternative option for unilateral TMJA, but the location of mandibulectomy and extent of bone removal from the mandible region have not been mentioned in the literature. This study aimed to validate the area of the mandibular body (rostral, middle or caudal) and amount of bony tissue that should be osteotomized during a segmental mandibulectomy for treatment of unilateral TMJA in cats. METHODS: In this block study, 30 cadaver heads of domestic shorthair cats were randomly divided into three groups of 10 specimens each based on the mandibular region that would undergo segmental mandibulectomy (rostral, middle and caudal). The size of the removed mandibular segment and pre- and postoperative vertical range of mandibular motion were compared for statistical purposes. RESULTS: A significant statistical difference was observed between the pre- and postoperative vertical range of mandibular motion between the rostral, middle and caudal segmental mandibulectomies (P <0.001). The mean postoperative recovered range of mandibular motion for the rostral, middle and caudal segmental mandibulectomies was 50.4%, 81.9% and 90.4%, respectively. CONCLUSIONS AND RELEVANCE: The caudal segmental mandibulectomy showed the highest postoperative vertical range of mandibular motion. The removal of a minimum of 1.2 cm of the caudal mandibular body was required to achieve nearly full recovery of presurgical mouth opening in the specimens of this study. The caudal segmental mandibulectomy may eliminate the risk of iatrogenic periarticular neurovascular damage inherent to more invasive surgeries performed at the temporomandibular joint area. When performed unilaterally, the caudal segmental mandibulectomy is a viable surgical alternative that may show a similar outcome to other surgical techniques.

Radiographic Assessment of the Feline Temporomandibular Joint with Oblique Projections: A Preliminary Ex Vivo Study.

Radiographic assessment of the temporomandibular joint in the domestic cat using conventional radiographic views can be challenging due to superimposition of overlying structures and the complex anatomy of the skull. The use of computed tomography, magnetic resonance imaging, and cone beam computed tomography to assess the temporomandibular joint in the cat has increased, but these modalities are not always available in general veterinary practices. Conventional radiography is still commonly used for first line assessment of the temporomandibular joint. The aim of this preliminary study was to determine optimal angle of obliquity of lateroventral-laterodorsal and laterorostral-laterocaudal (nose up lateral oblique) oblique radiographic views in the assessment of the temporomandibular joints in five feline mesaticephalic dry skulls. Visibility of the mandibular head, mandibular fossa, retroarticular process, and temporomandibular joint space were evaluated and scored by two veterinary radiologists. The results of this study identified that the dependent temporomandibular joint anatomy was best seen on the latero-10°-ventral-laterodorsal, latero-15°-ventral-laterodorsal, and latero-20°-ventral-laterodorsal, oblique views, and opposite lateral oblique views at these angulations may be helpful in characterization of this anatomy in clinical patients. The results also indicate that the laterorostral-laterocaudal (nose up lateral oblique) oblique view did not allow adequate discrimination of all TMJ anatomy at any angle, and is not recommended.