Unless there is a bony ankylosis, mandibular hypomobility is the result of fibrous adhesions between the mandible and the surrounding bones. The adhesions can be within the capsule of the TMJ or extra-articular. The primary treatment of mandibular hypomobility is aggressive physiotherapy.
Passive exercises should be performed several times each day until good range of motion has been established.
For those patients who do not regain mobility using passive exercises, active exercises can be prescribed.
2. Passive exercises
Patients should open their mouths as widely as possible and hold the mouth open for 5 seconds, followed by closure into their normal bite. This should be repeated five times. The goal is an interincisal dimension of at least 40mm.
Right and Left Lateral Excursions
Patients should move their mandible as far as possible to the right and hold it for five seconds, followed by returning to their normal bite. They should then move their mandible as far as possible to the left and hold it for five seconds. This should be repeated five times. The goal is lateral excursions of at least 12mm.
Patients should protrude their mandible as far as possible straight forward and hold it for five seconds followed by a return to their normal bite. This should be repeated five times. The goal is 10mm of protrusive excursion.
3. Active exercises
Place the fingers on the lower incisors and the thumbs on the upper canines. Relax the elevator muscles and push the jaws apart. This should be done several times throughout the day until an opening of at least 40mm is achieved.
For those patients requiring mechanical help with opening the mouth, commercially-available products can help. One example is the Therabyte®. This device is easy to use and allows the user to forcefully open the mouth by squeezing the handle of the device with one or both hands.
Stabilize the head by placing the hand on the side of the head towards which the mandible will be guided. With the other hand, place the thumb and index finger on the side of the chin. Relax the jaw muscles and push the lower jaw to the side as far as possible. Reverse hand positions and do the same in the opposite direction. This should be done several times during the day until the lateral excursions are at least 12mm in each direction.