Jaw Motion Rehabilitation Systems

Number: 0412

Policy

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 jaw motion rehabilitation system (e.g., the Therabite Jaw Motion Rehabilitation System, and the OraStretch press) medically necessary to treat mandibular hypomobility caused by radiation in persons with head and neck cancers.

  2. Aetna considers jaw motion rehabilitation system (e.g., the Therabite Jaw Motion Rehabilitation System, and the OraStretch press) experimental and investigational for all other indications because of insufficient evidence in the peer-reviewed literature, including any of the following conditions (not an all-inclusive list):

    • Closed lock treatment
    • Facial burns
    • Improvement of temporomandibular joint range of motion in individuals with Duchenne muscular dystrophy and spinal muscular atrophy
    • Mandibular coronoid hyperplasia
    • Maxillofacial trauma after surgical intervention
    • Non-surgical temporomandibular joint (TMJ) dysfunction
    • Oral burns
    • Orofacial pain
    • Post-surgical TMJ rehabilitation
    • Rehabilitation following facial trauma
    • Stroke
    • Treacher Collins syndrome
    • Trismus (including prophylactic training for the prevention of radiotherapy-induced trismus, and use of jaw motion rehabilitation systems with pentoxifylline plus vitamin E for the treatment of trismus in individuals with scleroderma).

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

Background

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:
  1. oral opening exercises;
  2. stacking tongue blades between the molars;
  3. continuous passive motion of the jaw; and/or
  4. 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
  1. it was a single-case report, and
  2. 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". 

Loorents et al (2014) noted that radiotherapy-induced trismus (RTIT) is a debilitating condition without any proven effective treatment.  These researchers investigated the effectiveness of prophylactic training to prevent RTIT during and up to 12 months after completed RT in patients with head and neck cancer (HNC); they also examined the incidence of RTIT.  A total of 66 consecutive patients from 2 RT clinics in Sweden were randomized into one of two groups:
  1. training with TheraBite® Jaw Motion Rehabilitation System™ or
  2. a control group.
Maximum interincisal openings (MIO) were recorded at baseline and once-weekly during treatment, 3, 6 and 12 months after completed RT.  Training frequency was recorded by patients in a log book.  There were no significant differences in MIO between the intervention and control groups at any of the measurement points.  Patients in both groups maintained their normal variation in MIO at 12 months after completed RT.  A small group of patients in the control group had a 17 % mean decrease in MIO by week 6 compared to baseline and improved their MIO by using the training program.  There was a significant mean difference in MIO from baseline to week 6 (3 mm, p = 0.018), and month 6 (2.7 mm, p = 0.04), for patients receiving 3D conformal radiotherapy.  There was a significant difference in MIO between patients treated with RT and concurrent chemotherapy compared to patients with RT only at 12 months (p = 0.033).  The authors concluded that patients with HNC undergoing high-dose RT do not need to be burdened with an intense prophylactic training program during RT and up to 12 months after completed RT.  Measurements of MIO during RT and up to 12 months after completed RT are recommended to identify a small risk group who are an exception and may need a training program.

In a prospective randomized controlled trial (RCT), Kraaijenga et al (2014) compared the application of the TheraBite (TB) Jaw Motion Rehabilitation System with a standard physical therapy (PT) exercise regimen for the treatment of myogenic temporo-mandibular disorder (TMD).  Myogenic TMD patients were randomized for the use of the TB device or for standard PT.  Mandibular function was assessed with the mandibular function impairment questionnaire (MFIQ).  Pain was evaluated using a visual analog scale (VAS), and MIO was measured using the disposable TB ROM scale.  Of the 96 patients randomized (46 TB, 50 standard PT exercises), 38 actually started with the TB device and 41 with the standard PT exercises.  After 6-week follow-up, patients using the TB device reported a significantly greater functional improvement (MFIQ score) than the patients receiving regular PT exercises (p = 0.0050).  At 6 weeks, no significant differences in pain, and active or passive MIO were found between the 2 groups.  At 3 months, patients in both treatment groups did equally well, and showed a significant improvement in all parameters assessed.  The authors concluded that this RCT on myogenic TMD treatment, comparing standard PT with passive jaw mobilization using the TheraBite Jaw Motion Rehabilitation System, showed that both treatment modalities are equally effective in relieving myogenic TMD symptoms, but that the use of the TB device has the benefit of achieving a significantly greater functional improvement within the first week of treatment.  The major drawbacks of this study were its small sample size (n = 36 receiving TB), lack of blinded assessment of outcomes, and short-term follow-up (6 weeks); and there were no significant differences in pain, and active or passive MIO between the TB and standard PT groups at 6 weeks.

Trismus

In a prospective study, Montalvo and colleagues (2017) examined the impact of structured exercise with TheraBite on trismus, trismus-related symptomatology, and health-related quality of life (HRQL) in patients with HNC.  A total of 15 patients with trismus (MIO less than or equal to 35 mm) after oncologic treatment for HNC, underwent a 10-week exercise program with the TheraBite device and were followed regularly.  Time between oncologic treatment and start of TheraBite exercise ranged from 0.7 to 14.8 years (average of 6.2); MIO, trismus-related symptoms, and HRQL was assessed before and after exercise and after 6 months.  A significant improvement in MIO was observed post-exercise (3.5 mm, 15.3 %, p = 0.0002) and after 6-month of follow-up (4.7 mm, 22.1 %, p = 0.0029).  A statistically significant correlation was found between increased MIO and fewer trismus-related symptoms.  The authors concluded that  exercise with TheraBite improved MIO and trismus-related symptoms in patients with trismus secondary to HNC; structured exercise with the TheraBite appeared to be beneficial for patients with trismus independent of time since oncologic treatment.  These finding from a small (n = 15) uncontrolled study need to be validated by well-designed studies.

In a 3-center, randomized controlled, open-label, feasibility study, Lee and colleagues (2018)  compared the efficacy of the Therabite jaw motion rehabilitation system with that of wooden spatulas to relieve and prevent trismus in patients who have had radiotherapy for stage 3 and 4 oral and oropharyngeal cancer.  Secondary aims were to examine the feasibility and the impact of exercise on health-related quality of life (QOL), and the use of health services following treatment.  These researchers compared the effectiveness and cost of the Therabite and wooden spatulas.  They studied compliance with exercises and health-related QOL, evaluated cost using 3 health economics measures, and conducted semi-structured interviews with patients.  Patients were randomized into 2 groups: the Therabite group (n = 37) and the wooden spatula group (n = 34).  All patients had some sense of jaw tightening before the study started.  Mean mouth opening after 6 months increased in both groups, but the difference between the groups was not significant (p = 0.39).  Completion rates for the 3 economic measures were good.  There was no significant difference between the 2 groups in frequency of contact with care services or in QOL.  Exercises during and after radiotherapy could ameliorate trismus in patients with stage 3 and 4 oral and oropharyngeal cancer, but differences between groups in efficacy, compliance, QOL, or use of hospital or community health services, were not significant.

Maxillofacial Trauma after Surgical Intervention

In a systematic review and meta-analysis, Dos Santos and colleagues (2020) evaluated rehabilitation strategies to reduce trismus, pain, and edema in patients with maxillofacial trauma.  These researchers carried out an electronic search in main databases, including studies published until November 2017.  Clinical trials that examined therapeutic techniques to improve mandibular ROM and to reduce pain and edema compared to other treatments were included.  A total of 9 studies were included in the review with different therapy modalities: photo-biomodulation, kinesiologic taping, hilotherapy, jaw exercises, and TENS.  Only 5 studies had available data to be included in a meta-analysis.  There were no differences between any of the proposed strategies and its controls to prevent trismus.  Individuals treated with hilotherapy presented less pain compared to controls.  Kinesiologic taping or hilotherapy reduced edema when compared to controls daily until post-operative day 3.  The authors concluded that there is diversity among the proposed rehabilitation techniques, and types of fractures and there were few numbers of included subjects in each study.  These researchers stated that findings obtained in this review did not promote evidence to guide the use of non-drug rehabilitation techniques in patients with maxillofacial trauma after surgical intervention.

TheraBite for Improvement of Temporomandibular Range of Motion in Individuals with Duchenne Muscular Dystrophy and Spinal Muscular Atrophy

Morris and colleagues (2020) noted that individuals with Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA) develop impaired oral function because of reduced temporomandibular joint (TMJ) ROM, which affects feeding and oral hygiene activities of daily living (ADLs).  In a case-series study, these researchers examined if the TheraBite would improves ROM.in these patients.  The intervention duration of this trial varied from 7 to 30 months; and treatment frequency varied from weekly to consultative (several times per year).  The setting of treatment varied depending on the ease of transportation for the subject and caregivers; 2 subjects were treated in an outpatient medical clinic.  The other was provided consultative care during multi-disciplinary medical clinics and completed a home program.  Subjects included 2 adults with DMD and 1 with SMA; intervention was stretching protocol using the TheraBite.  Temporomandibular active ROM (AROM) was determined using a disposable TheraBite oral goniometer.  Passive ROM (PROM) was determined using the adhesive scale on the TheraBite.  Measures were taken at baseline, each intervention or consultation, and the end of care; ADL participation and caregiver burden were measured at the end of intervention.  For subjects with DMD, AROM remained unchanged; however, PROM increased by 40 % to 65 %.  The subject with SMA demonstrated 33 % and 47 % improvements in AROM and PROM, respectively.  Subjects or caregivers reported improved feeding function, improved oral hygiene, or reduced fatigue.  The authors concluded that the TheraBite may improve temporomandibular PROM in individuals with DMD and temporomandibular AROM and PROM in individuals with SMA; it may also improve ADL function and consequently reduce caregiver burden.  Moreover, these researchers stated that further investigation is needed.

TheraBite Combined with Pentoxifylline plus Vitamin E for the Treatment of Trismus in Individuals with Scleroderma

Reed and colleagues (2020) provided evidence supporting the off-label use of pentoxifylline and vitamin E especially by dentists with TheraByte to reduce trismus in 2 patients with scleroderma.  The authors concluded that pentoxifylline plus vitamin E with TheraBite appeared to be effective in reducing trismus in scleroderma patients.  Moreover, these researchers stated that additional clinical research is needed.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

Other CPT codes related to the CPB:
95851 Range of motion measurements and report (separate procedure); each extremity, (excluding hand) or each trunk section (spine)
97110 Therapeutic procedure, one or more areas, each 15 minutes; therapeutic exercises to develop strength and endurance, range of motion and flexibility
97530 Therapeutic activities, direct (one-on-one) patient contact (use of dynamic activities to improve functional performance), each 15 minutes
97535 Self care/home management training (eg, activities of daily living (ADL) and compensatory training, meal preparation, safety procedures, and instructions in use of assistive technology devices/adaptive equipment) direct one-on-one contact, each 15 minutes

HCPCS codes covered if selection criteria are met:
E1700 Jaw motion rehabilitation system
E1701 Replacement cushions for jaw motion rehabilitation system, package of six
E1702 Replacement measuring scales for jaw motion rehabilitation system, package of 200

ICD-10 codes covered if selection criteria are met:
C76.0 Malignant neoplasm of head, face and neck
M26.69 Other specified disorders of temporomandibular joint
Z92.3 Personal history of irradiation

ICD-10 codes not covered for indications listed in the CPB: (not all-inclusive):
Numerous options Burn and corrosion of head, face and neck, sequela [Codes not listed due to expanded specificity]
G12.0 – G12.1, G12.25, G12.8 – G12.9 Spinal muscular atrophy
G45.0 - G45.2, G45.4 - G45.9 Transient cerebral ischemic attacks and related syndromes
G71.01 Duchenne or Becker muscular dystrophy
I60.00 - I67.2, I67.4 - I69.998 Cerebrovascular diseases
M26.03 Mandibular hyperplasia [coronoid]
M26.601 - M26.609 Temporomandibular joint disorders
Q75.4 Mandibulofacial dysostosis [Treacher Collins Syndrome]
R25.2 Cramp and spasm [trismus]
S00.00x+ - S09.93x+ Injuries to the head
T20.00x+ - T20.79x+ Burn and corrosion of head, face and neck
Z48.814 Encounter for surgical aftercare following surgery on the teeth or oral cavity [for maxillofacial trauma after surgical intervention]
Z48.89 Encounter for other specified surgical aftercare [for maxillofacial trauma after surgical intervention]

Pentoxifylline plus vitamin E:

HCPCS codes not covered for indications listed in the CPB:
Pentoxifylline plus vitamin E – No specific code

ICD-10 codes not covered for indications listed in the CPB: (not all-inclusive):
R25.2 Cramp and spasm [trismus]
M34.0 – M34.9 Systemin sclerosis [scleroderma]

The above policy is based on the following references:

  1. Barrett VJ, Martin JW, Jacob RF, et al. Physical therapy techniques in the treatment of the head and neck patient. J Prosthet Dent. 1988;59:343-346.
  2. Buchbinder D, Currivan RB, Kaplan AJ, et al. Mobilization regimens for the prevention of jaw hypomobility in the radiated patient: A comparison of three techniques. J Oral Maxillofac Surg. 1993;51(8):863-867.
  3. Cohen EG, Deschler DG, Walsh K, Hayden RE. Early use of a mechanical stretching device to improve mandibular mobility after composite resection: A pilot study. Arch Phys Med Rehabil. 2005;86(7):1416-1419.
  4. Dijkstra PU, Kalk WW, Roodenburg JL. Trismus in head and neck oncology: A systematic review. Oral Oncol. 2004;40(9):879-889.
  5. Dos Santos KW, Rech RS, Wendland EMDR, Hilgert JB. Rehabilitation strategies in maxillofacial trauma: Systematic review and meta-analysis. Oral Maxillofac Surg. 2020;24(1):1-10.
  6. Fernandez Ferro M, Fernandez Sanroman J, Sandoval Gutierrez J, et al. Treatment of bilateral hyperplasia of the coronoid process of the mandible. Presentation of a case and review of the literature. Med Oral Patol Oral Cir Bucal. 2008;13(9):E595-E598.
  7. Fleming TJ. Oral tissue changes of radiation-oncology and their management. Dent Clin North Am. 1990;34:233-237.
  8. Friedman MH. Closed lock. A survey of 400 cases. Oral Surg Oral Med Oral Pathol. 1993;75(4):422-427.
  9. Gaziano JE. Evaluation and management of oropharyngeal dysphagia in head and neck cancer. Cancer Control. 2002;9(5):400-409.
  10. Gibbons AJ, Abulhoul S. Use of a Therabite appliance in the management of bilateral mandibular coronoid hyperplasia. Br J Oral Maxillofac Surg. 2007;45(6):505-506.
  11. King GE, Toth BB, Fleming TJ. Oral dental care of the cancer patient. Tex Dent J. 1988;105:10-11.
  12. Kouyoumdjian JH, Chalian VA, Hutton C. An intraoral positive-pressure device for treatment of trismus. Oral Surg. 1986;61(5):456-458.
  13. Kraaijenga S, van der Molen L, van Tinteren H, et al. Treatment of myogenic temporomandibular disorder: A prospective randomized clinical trial, comparing a mechanical stretching device (TheraBite®) with standard physical therapy exercise. Cranio. 2014;32(3):208-216.
  14. Lee R, Yeo ST, Rogers SN, et al. Randomised feasibility study to compare the use of Therabite® with wooden spatulas to relieve and prevent trismus in patients with cancer of the head and neck. Br J Oral Maxillofac Surg. 2018;56(4):283-291. 
  15. Loorents V, Rosell J, Karlsson C, et al.  Prophylactic training for the prevention of radiotherapy-induced trismus - a randomised study. Acta Oncol. 2014;53(4):530-538.
  16. Maloney GE, Mehta N, Forgione AG, et al. Effect of a passive jaw motion device on pain and range of motion in TMD patients not responding to flat plane intraoral appliances. Cranio. 2002; 20(1):55-66.
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  18. Melchers LJ, Van Weert E, Beurskens CH, et al. Exercise adherence in patients with trismus due to head and neck oncology: A qualitative study into the use of the Therabite. Int J Oral Maxillofac Surg. 2009;38(9):947-954.
  19. Montalvo C, Finizia C, Pauli N, et al. Impact of exercise with TheraBite device on trismus and health-related quality of life: A prospective study. Ear Nose Throat J. 2017;96(1):E1-E6.
  20. Morris EHL, Estilow T, Glanzman AM, et al. Improving temporomandibular range of motion in people with Duchenne muscular dystrophy and spinal muscular atrophy. Am J Occup Ther. 2020;74(2):7402205080p1-7402205080p10.
  21. Nicalaou N. Prevention and management of radiation toxicity. In: Cancer Management: A Multidisciplinary Approach. 7th ed. R Pazdur, LR Coia, WJ Hoskins, LD Wagman, eds. Melville, NY: PRR; 2003; Ch. 46: 909-939.
  22. No authors listed. National Institutes of Health Consensus Development Conference Statement: Oral complications of cancer therapies: Diagnosis, prevention, and treatment. J Am Dent Assoc. 1989;119(1):179-183.
  23. Reed DN, Hall DL, Cottle JH, et al. Dental management of scleroderma patients using pentoxifylline plus vitamin E with and without TheraBite ® to reduce trismus: Two case reports and brief review of literature. Clin Case Rep. 2020;8(2):247-253.
  24. Rocabardo M, Johnston BE, Blakney MG. Physical therapy and dentistry: An overview. J Craniomand Pract. 1983;1:46-49.
  25. Schweiger JW. Oral complications following radiation therapy: A five-year retrospective report. J Prosthet Dent. 1987;58:78-82.
  26. Shulman DH, Shipman B, Willis FB. Treating trismus with dynamic splinting: A cohort, case series. Adv Ther. 2008;25(1):9-16.
  27. Shulman DH, Shipman B, Willis FB. Treating trismus with dynamic splinting: A case report. J Oral Sci. 2009;51(1):141-144.
  28. Stubblefield MD, Manfield L, Riedel ER. A preliminary report on the efficacy of a dynamic jaw opening device (dynasplint trismus system) as part of the multimodal treatment of trismus in patients with head and neck cancer. Arch Phys Med Rehabil. 2010;91(8):1278-1282.
  29. Therabite Corporation. Therabite Jaw Motion Rehabilitation System. West Chester, PA: Therabite; 2002. Available at: http://www.therabite.com. Accessed December 9, 2002.
  30. Toth BB, Frame RT. Dental oncology: The management of disease and treatment-related oral/dental complications associated with chemotherapy. Curr Probl Cancer. 1983;7:7-35.
  31. Toth BB, Martin JW, Fleming TJ. Oral and dental care associated with cancer therapy. Cancer Bull. 1991;43:397-402.
  32. Toth BB, Martin JW, Fleming TJ. Oral complications associated with cancer therapy: An M.D. Anderson Cancer Center experience. J Clin Periodontol. 1990;17:508-515.
  33. van der Geer SJ, Reintsema H, Kamstra JI, et al. The use of stretching devices for treatment of trismus in head and neck cancer patients: A randomized controlled trial. Support Care Cancer. 2020;28(1):9-11.
  34. van der Molen L, van Rossum MA, Rasch CR, et al.  Two-year results of a prospective preventive swallowing rehabilitation trial in patients treated with chemoradiation for advanced head and neck cancer. Eur Arch Otorhinolaryngol. 2014;271(5):1257-1270.
  35. Wenghoefer M, Martini M, Anwander T, et al. Hyperplasia of the coronoid process: Diagnosis and treatment. Mund Kiefer Gesichtschir. 2006;10(6):409-414.