TMD Model Animations
See how the model helps you to explain (1) Normal and abnormal head postures, (2) Whiplash and TMJ disorders, (3) Normal mouth opening and closing, (4) Protrusive opening, (5) Chewing motion and stable occlusion, (6) Anterior bite, (7) Posterior bite, (8) Lack of occlusal support and (9) Occlusal appliance
The neutral or ortho-static head position (with horizontal Frankfurter plane) will allow healthy TMJ, craniovertebral, cervico-thoracic functions, and a stable occlusion (‘bite’). A forward head position (loosen screws at the back of the model and move the head all the way forward) may induce a number of changes.
- Increased tension of the supra- and infra-hyoid muscles, and subsequently the jaw closing muscles
- A decreased sub-occipital space enabling neuro-vascular compression enabling headache and dizziness to occur
- An increased cervico-thoracic space will increase the tension in the neck and shoulder girdle considerably.
Sudden impact accidents (rear-end car collisions) can strain jaw muscles and the TMJ by a ‘whiplash’ motion of the head. As the head is rotated and thrown backwards, the mouth will be opened and the jaw will be pulled backwards.
Healthy jaw opening and closing movements are enabled by pain-free and frictionless TMJ motions. The condylar head of the mandible and the articular disc will act synchronously during a great variety of movements. Initial rotation (10 to 15 degrees) can be demonstrated at the start of mouth opening followed by a large translatory movement toward full mouth opening. Slight or moderate anterior displacement of the disc will cause clicking or even locking.
Patients with a large horizontal overbite (upper dental arch is placed forward) will generally demonstrate an increased initial forward movement at the start of mouth opening (‘Sunday-bite’). This action may cause an increased looseness of the TMJ capsule and (intra-)articular ligaments. Disc displacement may be the result of this type of movement.
A stable occlusion with sufficient dental support will generally ensure proper jaw muscle function during chewing. There are no significant dental interferences: maximum or optimum occlusion. The condyle-disc complex is now preserved centrally in the temporal fossa. You can now demonstrate a healthy chewing motion by opening the mouth slightly and occluding and articulating against the distal facets of the upper teeth.
Move the upper dental arch 2 to 3 millimeters forward (loosen and tighten screw). Now bring the dental arches together and observe that this interference causes an anterior positioning of the condyle disc complex. Displacement in other planes of movement may be assumed.
Move the lower dental arch 2 to 3 millimeters forward (loosen and tighten screw). Now bring the dental arches together and observe that the interference causes a posterior or distal positioning of the condyle. The disc will, as a result, become displaced more anteriorly to the condyle. Again, displacement in other planes may be assumed.
Lack of molar support may be an important etiological factor in developing TMJ pathology. The use of an occlusal appliance (enclosed) may be the treatment of choice in the initial phase. The indication for further treatment by means of prosthetic dentistry, dental implants, orthodontics, or other dental-surgical treatments can be motivated more easily by the clinician as an effective future management of healthy jaw functions.
An occlusal appliance will stabilize the occlusal relationship between the dental arches and jaws and will relax the jaw muscles. Subsequently, the TMJs will be stabilized and de-loaded. The appliance may also be effective in avoiding overloading of the dental structures, including dental implants and crown and bridge work, in the case of clenching and grinding.