Note: Some plans exclude coverage of jaw stretch devices as equipment available over the counter without a prescription. Please check benefit plan descriptions.

1. Aetna considers the Therabite Jaw Motion Rehabilitation System medically necessary to treat mandibular hypomobility caused by radiation in persons with head and neck cancers.

2. Aetna considers the Therabite Jaw Motion Rehabilitation System experimental and investigational for all other indications because of insufficient evidence in the peer-reviewed literature, including any of the following conditions:

   1. Closed lock treatment
   2. Facial burns
   3. Mandibular coronoid hyperplasia
   4. Non-surgical temporomandibular joint (TMJ) dysfunction
   5. Oral burns
   6. Orofacial pain
   7. Post-surgical TMJ rehabilitation
   8. Rehabilitation following facial trauma
   9. Stroke
   10. Treacher Collins syndrome
   11. Trismus.

See also CPB 0405 - Mechanical Stretching Devices for Contracture and Joint Stiffness on the use of dynamic splinting for the treatment of trimus.

Most head and neck cancers are treated with surgery, radiation, or a combination of the 2 modalities.  The choice of treatment depends primarily on the anatomic site, extent and histologic grading of the tumor, and the presence of infection.  Modern reconstructive techniques permit cancer patients, especially those with head and neck malignancies, to undergo more immediate reconstruction and thereby achieve better functional outcomes while still progressing through multimodality treatment in a timely manner.  However, the more aggressive the cancer therapy, the more it places patients at risk for oral complications related to treatment.

One of the major complications from therapeutic administration of ionizing radiation to the head and neck is mandibular hypomobility -- a reduction in mandibular range of motion (ROM) caused by radiation-induced scarring and contraction of soft tissues surrounding the jaw.  Clinically, the severity of mandibular hypomobility is related to the radiation dose, volume of tissue treated, and age of the patient.

Mandibular hypomobility is treated by stretching the scar tissue.  Methods commonly used to stretch the scar tissue and increase mandibular ROM include: (i) oral opening exercises; (ii) stacking tongue blades between the molars; (iii) continuous passive motion of the jaw; and/or (iv) stretching the jaw using custom-made mechanical devices.  One such custom-made device is the Therabite, a threaded screw-type instrument that is placed between the teeth and turned to gradually open the jaw, much like a car jack.  Preliminary evidence indicates that the Therabite is more effective than other modalities in maintaining and/or improving mandibular ROM in irradiated patients.  There are, however, inadequate outcomes data comparing the Therabite to more conventional methods to support the use of Therabite for any other condition. Orabite is another brand of jaw stretch device that is not longer on the market.

Melchers and associates (2009) examined the factors that may influence Therabite exercise adherence, how these interrelate and provided aims for interventions to increase adherence.  These researchers performed a multi-center, formal-evaluative qualitative retrospective study.  A total of 21 patients treated for head-neck cancer were interviewed in semi-structured, in-depth interviews.  Internal motivation to exercise, the perceived effect, self-discipline and having a clear exercise goal influenced Therabite exercise adherence positively.  Perceiving no effect, limitation in Therabite opening range and reaching the exercise goal or a plateau in mouth opening were negative influences.  Pain, anxiety and physiotherapists could influence adherence both positively and negatively.  Based on the results, a model for Therabite exercise adherence was proposed.  It is important to signal and evaluate the factors that negatively influencing Therabite adherence, especially before there is a perceived effect.  The authors stated that research is needed to examine why some patients do not achieve results despite high exercise adherence, to identify effective exercise regimens and to assess proposed interventions aimed to increase Therabite exercise adherence.

Shulman et al (2008) retrospectively evaluated the effect of the Dynasplint Trismus System (DTS; Dynasplint Systems Inc., Severna Park, MD) for patients who were recently diagnosed with trismus following radiation therapy, dental treatment, oral surgery, or following a neural pathology such as a stroke.  These researchers reviewed 48 patient histories (treated in 2006 to 2007), and divided into 4 cohort groups (radiation therapy for head/neck cancer, dental treatment, oral surgery, or stroke), to measure the efficacy of this treatment's modality.  Patients were prescribed the DTS after diagnosis of trismus based on examination that showed less than 40 mm maximal interincisal (opening) distance (MID).  The DTS uses low-load, prolonged-duration stretch with replicable, dynamic tension to achieve longer time at end range (of motion).  Each patient used this device for 20 to 30 mins, 3 times per day.  This cohort case series showed that there was a statistically significant difference within all patient groups (p < 0.0001; t = 10.3289), but there was not a significant difference between groups (p = 0.374).  The biomechanical modality of DTS with a low-load, prolonged-duration stretch was attributed to the success in reducing contracture in this study.  This improved range of motion, allowing patients to regain the eating, hygiene and speaking patterns they had before developing trismus.  The main drawbacks of this study were the lack of a control group and small sample size.  The authors stated that "future studies should include a randomized, controlled, crossover study of this unit to compare the efficacy of treating trismus, and a case/control study could evaluate prevention of trimus with the DTS".

In a case report, Shulman et al (2009) described the use of dynamic splinting to reduce trismus that occurred in a patient following multiple dental procedures.  A 26-year old man was referred for severe trismus and pain following 3 dental procedures on the lower right molars.  The patient presented with MID of only 5-mm and mastication muscle spasticity.  Following physical therapy (i.e., massage, moist heat, neuromuscular electrical stimulation, and ultrasound) 3 times per week for 2 months and additional treatment of dynamic splinting for 4 weeks (TID), the patient increased his MID to 52 mm and returned to normal eating and speaking.  The main drawbacks of this study were (i) it was a single-case report, and (ii) lack of follow-up

In a retrospective, cohort study, Stubblefield et al (2010) examined the effectiveness of a dynamic jaw opening device as part of a multi-modal treatment strategy for trismus in patients with head and neck cancer (n = 20).  All patients underwent assessment by a board-certified physiatrist and were referred to physical therapy for delivery of the DTS and instructed to progress use of the DTS to 30 mins 3 times a day.  Additional modalities for the treatment of trismus including pain medications and botulinum toxin injections were prescribed as clinically indicated.  Main outcome measures included change in MID as documented in the medical record.  The use of the DTS as part of multi-modal therapy including physical therapy, pain medications, and botulinum toxin injections as deemed clinically appropriate resulted in an overall improvement of the MID from 16.5 mm to 23.5 mm (p < 0.001).  Patients who could comply with the treatment recommendations for DTS treatment did better than those who could not, with an improvement of the MID from 16 mm to 27 mm (p < 0.001) versus 17 mm to 22 mm (p = 0.88).  The authors concluded that the DTS is a safe and effective component of a multi-modal strategy for improving trismus associated with head and neck cancer and its treatment.  Moreover, they stated that further investigation is needed to determine the relative effectiveness of the treatment modalities available for trismus including physical therapy and other jaw stretching devices.  This was a retrospective pilot study with a small sample size (n = 20); and its finding were confounded by the use of other modalities.  Furthermore, the authors stated that "a large randomized prospective trial that directly compares DTS with TheraBite and each to physical therapy and a non-treatment group for both acute and chronic trimus patients would be potentially illuminating".