The jaw is one of the most highly used joints in the human body and is often injured, creating the need for JAMSS.
What is JAMSS?
By Dr Bradley Eli, DMD, MS
Jaw and Muscle Sprain/Strain (JAMSS) involves acute trauma to the joints or muscle groups in the jaw joints, including masticatory muscles (muscles that coordinate opening and closing of the jaw, chewing, and other functions) upper cervical muscles in the neck, and other facial muscles.
Muscles, cartilage, tendons, and ligaments hold the mandible (lower jawbone) together with the maxilla (upper jawbone) and the temple bone of the skull to form the temporomandibular joint (TMJ) for each side of the jaw. For simplicity, we refer to this region in the body as the jaw joint system.
JAMSS can be caused by unintended strain to the jaw.
For example, when taking a big bite of an apple or after an extended yawn. JAMSS may also be due to, or more traumatic injury such as a blow to the jaw, chin lacerations, sports injury, or whiplash/concussion from a car accident. Long dental procedures that open the jaw too wide or for too long a period can also result in JAMSS. It is common to be unaware of pain for hours later or the next morning when it becomes painful to open the mouth or chew. Jaw sprain/strain can even show up from a progressive activity like singing or playing an instrument.
The Jaw joints along with jaw, head, and neck muscles work together to open, close, and move the jaw from side to side. This allows both relax and contract, making many different movements, namely the rotating and gliding actions when you speak, chew, smile, and swallow. Problems with the jaw can be challenging due to the jaw joint relationship to these muscle groups.
Multiple nerves run throughout the jaw joint system, including the trigeminal nerve, which is responsible for sensation in the face, mouth, and tongue as well as biting and chewing. Any disruption of this complex system can be painful, and dysfunction can be stressful.
People need a Holistic Approach to JAMSS
The jaw joint system is integrally related to the neck or cervical system. This is a complicating factor in the diagnosis and treatment of head, neck and jaw pain given the inconsistency in training and terminology. (TMJ disorders, whiplash, tension headache, and neck pain share common features that should be generally understood in healthcare, but diagnosis and treatments are siloed into different disciplines.) For the person in pain seeking answers, however, a holistic approach viewing these as integrated problems is vitally important for healing, symptom resolution, and return to normal activity.
Perhaps you have never heard of JAMSS before or perhaps you prefer to call it jaw muscle and joint pain, or TMJ pain. We prefer JAMSS as the more accurate term. It is a common acute injury that is similar to acute ankle and wrist sprain/strain; however, it is different than joint disk disorders, myofascial pain, muscle contracture and even muscle spasm.
Orofacial Therapeutics Offers Help for Jaw Pain
Our JAMSS campaign:
- To raise awareness of the causes, signs, and symptoms of jaw sprain/strain and the need for a simple treatment plan that people can self-administer or obtain from urgent care, primary care, or general dentist.
- To prevent delayed recovery and chronic pain that could have been treatable with early intervention. Currently, there is little consistency in the medical field or dental field for acute JAMSS; this and other key recommendations were published in a special report commissioned by the National Institutes of Health and National Academy of Science, Engineering and Medicine (NASEM)’s report on Temporomandibular Disorder.
JAMSS Medical Terminology
There are specific medical ICD-10 diagnostic codes for jaw sprain/strain and yet the terminology used in everyday practice varies from clinician to clinician. For the most current medical thinking, download the NASEM Report mentioned above. 
Here are some of the medical terms that have been used in medicine, dentistry, and physical medicine:
1) Myalgias, masticatory myalgia, regional craniocervical myalgia.
2) Myofascial pain with regional pain and myofascial pain with referral of pain.
3) Myogenous masticatory pain.
5) Subluxation of the mandible.
6) Inflammation of the jaw joint.
8) Hyperextension of the jaw.
In our opinion, masticatory muscle strain and jaw joint spraincommonly coexist; therefore, it is not essential to differentiate treatments in the acute stage.
According to a July 2019 Summary of Findings from the OPPERA Prospective Cohort Study of Incidence of First-Onset Temporomandibular Disorders: Implications and Future Directions article, “intrinsic injuries were the predominant types (29.1%), and these included yawn injuries which were the most frequent (13.1%), followed by injuries due to sustained opening (11.4%), and injuries due to both yawning and sustained opening (4.6%). Only a small percentage of incident TMD cases had extrinsic injuries (5.1%), which included either sport injuries, dental injuries, head injuries, or motor vehicle whiplash injuries exclusively, or a combination of whiplash, motor vehicle, sports, head, and shoulder-neck injuries”.
The incidence rates reported in these findings by author Sonia Sharma, BDS, MS, PHD demonstrate the need for heightened awareness of the conditions and treatment options for JAMSS universally across healthcare professions. Episodes of acute TMD pain symptoms are common and patients present with pain and suffering in a variety of clinical settings. We advocate for early intervention to prevent delayed recovery, re-injury, and reliance on more costly medical care.
More In-Depth JAMSS Articles to Come
We have organized a series of articles that we hope you will discuss and share with others. We are not providing medical advice here, nor are we covering each topic in depth. We are interested in your feedback and suggestions, questions, and invitations to collaborate on research. You may want to read about our clinical protocols for treatment for acute jaw and muscle sprain/strain.
Watch this video on the Etiology of Jaw and Muscles Sprain/Strain (JAMSS) for a better understanding.
This shows the etiology of Jaw and Muscles Sprain/Strain (JAMSS) that
sometimes can occur from a longer dental procedure, or for a patient who has a limited range of motion as an existing condition. As with other joints in the body, there are 4 grades of joint mobility:
1. Normal resting range of motion (teeth apart, tongue up)
2. Normal active range of motion (25 to 45 mm)
3. Maximum voluntary range of motion (45 to 60 mm)
4. Maximum involuntary range of motion (by application of a bite block, your hand or tool resting on the mandible.)
While the jaw joint and musculature are highly adaptable, in some instances the muscles become hyperactive and are in conflict when the lateral pterygoid is required to hold the jaw open on a sustained basis. This video demonstrates what can happen in cases of delayed onset of JAMSS. It is important that your staff be informed of this condition and encourage patients to call your office immediately if this occurs, rather than wait and go to Urgent Care.
What is Orofacial Pain?
The most common cause of facial pain is a group of conditions called temporomandibular joint and muscle disorders (TMJDs). TMJDs are the second most commonly occurring musculoskeletal condition resulting in pain and disability and affect approximately 5-12% of the population with an annual estimated cost of $4 billion.
Some disorders of the jaw joint systems overlap with headache, fibromyalgia, or other comorbidities. Orofacial pain specialists are trained to coordinate care with dentists, neurologists, rheumatologists, otolaryngologists, physical therapists, and health psychologists. Some TMJ dentists are trained to cross-refer patients for physical therapy and chiropractic care. Together, they may be your pain management team.
Members of the orofacial pain community are working to develop training programs for frontline dental and medical providers per these recommendations:
“Diagnostic tools and resources for TMDs should be improved for the initial assessment by primary care clinicians and dentists, and for referrals to specialists, as needed. These efforts should include the development of decision criteria for risk stratification to aid in identifying patients who are likely to escalate from self-limiting and localized symptoms to a systemic pain condition and then to high-impact pain.” – Temporomandibular Disorders: Priorities for Research and Care 
Given that the jaw joint system is one of the most adaptive parts of the body, continuously changing with growth, age and use, promoting awareness of symptoms and oral habits and providing patient education is critical. In this section, we include information that can be helpful for doctors and their patients.
Understanding how to care for jaw sprain/strain should be as common as caring for wrist or ankle sprain. Every person, parent, coach, primary care, and dental provider should have a common understanding of the signs and symptoms of care for JAMSS, and simple treatment options. There are risks associated with waiting too long for treatment or being referred to the wrong healthcare provider. Here are some of our concerns, as orofacial pain specialists that treat patients whose conditions could have been addressed with early intervention:
- People with treatable jaw sprain/strain suffer and their condition becomes harder and most costly to treat.
- Medical professionals write prescriptions that reduce the pain symptoms, but do not address the underlying risk factors for re-injury and protective actions to encourage healing.
- There is a noticeable gap in care for patients who need to learn self-care to prevent oral habits that cause re-injury or delayed recovery.
- Many patients cannot afford a complete diagnostic workup and treatment plan from a TMJ dentist or orofacial pain specialist, which is compounded by the lack of medical/dental insurance coverage and the shortage of available experts to treat this patient population. In our opinion, a comprehensive diagnostic exam is not merited for acute jaw sprain/strain cases if early intervention is provided.
TMJ and TMD
JAMSS is an acute temporomandibular joint disorder (TMD), but we encourage caution in using this term because TMD refers to 30 clinically different disorders. Not only do we want to raise awareness of the causes and treatment options for jaw sprain/strain, but in our articles here, we want to draw distinctions between acute jaw sprain/strain and other, more complex TMJ disorders requiring extensive treatment from a specialist.
In this section, we will discuss the importance of access to care, treatment options for patients and need for a complete medical history before diagnosing complex TMJ disorders.
Jaw Pain Treatments
In our experience at Orofacial Therapeutics, an estimated 70% of persons with mild head, neck, and jaw trauma or injury (without significant prior history) who are compliant with simple treatment (described in articles in this section) will notice an improvement in jaw and neck function and reduced pain levels within four weeks. In this section, we will discuss several of the treatment options for JAMSS and common TMJ disorders.
We welcome your comments and questions.
Dr. Brad Eli, DMD, MS is a graduate of UCLA’s post-doctoral Orofacial Pain program. The field of orofacial pain, temporomandibular disorders, and treatment of sleep disorders became the 12th specialty of dentistry in 2020. Over the past 29 years of clinical practice specializing in orofacial pain and sleep, Dr. Eli has also been on the educational staff at university hospitals, pain centers, and the clinical staff of Southern California hospitals.
 National Academies of Science, Engineering and Medicine 2020. Temporomandibular Disorders: Priorities for Research and Care. Washington DC: The National Academies Press.
 Facial Pain retrieved from National Institute of Health/National Institute of Dental and Craniofacial Pain, https://www.nidcr.nih.gov/DataStatistics/FinddatabyTopic/FacialPain, March 2021
 Footnote from NIH March highlights, “Temporomandibular Disorders: Priorities for Research and Care”, https://www.ncbi.nlm.nih.gov/books/NBK558000/, March 2020