TRISMUS - A Quick Primer

What is trismus? Trismus is defined as any restriction to mouth opening. 

What are the health implications? Implications include difficulty speaking, eating, maintaining oral hygiene and receiving dental procedures Trismus may even complicate intubation.

What causes trismus? Radiation treatment for head and neck cancer, surgery, trauma and TMJ problems all may lead to the development of trismus. 

What is the typical measure of mouth opening? The average adult opening is 50 mm and it is highly correlated with body size.

How do you diagnose trismus? The clinical diagnosis of trismus is a maximum interincisal opening (MIO) of 35mm of less. Using the 3-finger diagnostic (see above picture) it is indicated at 2-fingers or less.

How do you measure for trismus? For precise measurements of MIO you can use a rotational or a prong scale. You may also use the 3-finger method which accounts for body size. The patient should be able to stack 3-fingers of the non-dominant hand vertically in between their upper and lower teeth, 2-fingers or less signifies trismus. 


What are the major risk factors for trismus? Radiation is the major risk factor. The higher the dosage of radiation the higher the risk. Radiation that affects the areas of the pterygoid and masseter also increases risk. Further risk factors include initially presenting with a limited MIO, being at a later stage of cancer and being older.

How common is trismus in patients with HNC? 32-50% of patients will develop trismus. Location of radiation significantly impacts the incidence. In patients with radiation to the pterygoid area, incidence may be as high as 93%.



How can you prevent and treat trismus? Exercise therapy and treatment decreases both the incidence and severity of trismus. Jaw motion rehab systems such as the OraStretch® press are the most efficacious. Unassisted exercise such as stretching the mouth with ones fingers or own muscles is second best, with tongue blades falling short in third. 


What is the OraStretch press? 

The OraStretch press is a jaw motion rehab system that helps prevent and treat trismus. It is a handheld, patient controlled device with documented efficacy. It comes in 3 different sizes (standard, pediatric, edentulous) and opens to the average adult opening of 50 mm. 

What are the therapy protocols?  There are 2 main protocols.

    5-5-30  - Best for radiation fibrosis. This protocol is conducted five                      times a day, with five stretches each time, holding each                        stretch for 30 seconds.

    7-7-7    - Best for joint function, tissue molding, fibrosis prevention.                      This protocol is conducted seven times a day, with seven                      stretches each time, holding each stretch for seven                                seconds and relax seven seconds.


         For more protocols, please visit OraStretch press Protocols 

What are OraStretch press Dynamic BandsSeen below, the silicon bands are used for dynamic stretching and active resistance therapy. Great for overcoming therapy plateaus and non-progression as well as bite muscle training.

How do I order it for a patient? Ordering is simple! Complete and return our Prescription-Order form. We will confirm insurance coverage, pre-auth equipment, bill the insurer and work with the patient to provide the equipment. 

** The OraStretch press includes free shipping, free size exchanges and a lifetime warranty **

Discover more about the OraStretch press and other products on our website, including an ordering guide, prescription-order form, product comparisons, and clinical research at
 CranioRehab.comOrdering an OraStretch press is easy. Complete and fax/email us our Rx-Order form and we will confirm insurance coverage and contact the patient.   

If you have any questions or requests, please call us at 1-800-206-8381 or email us at [email protected]*See website or contact us for more details.

Noted research details can be found at

OraStretch, Salvate, Nutrisqueeze, Helping People Say Ahhhhh! are trademarks of                                             CranioMandibular Rehab, Inc. 



Date 6/5/2018

Parthenia Hand

Date 2/14/2023

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