Temporomandibular joint model: anatomic and radiologic comparison between rat and human

The temporomandibular joint (TMJ) is a complex anatomic structure with various pathologies as fractures, ankylosis or degenerative diseases. Few animal models already exist and the current study aims at demonstrating that rats' TMJ could be considered as a model, using anatomic dissection and radiology. Five adult Wistar rats were dissected to explore the soft and bone anatomy of the TMJ. Five more adult Wistar rats underwent a CT scan to measure size and angles of the condyle. The angles between the condyle and the mandible corpus were observed to be different both in the sagittal plane (150A degrees vs. 125A degrees in human) and the transversal plane (140A degrees vs. 180A degrees). The condyle axis is sagittal and drop-shaped and there is no anterior eminence in rats' temporal fossa. However, the other anatomic structures proved to be quite similar. The temporomandibular joints in human and rat are close and only few anatomic differences have been reported. Rats thus appear as an interesting and cheap alternative to model TMJ.