TMJ Disorder Causes Guide: Understanding Several Contributing Factors, Not Just One

Temporomandibular (TMJ) disorders more often arise from several overlapping contributing factors than from a single cause. The Korea Disease Control and Prevention Agency (KDCA, 질병관리청) sees the main causes as chronic tissue fatigue and microscopic damage from bad chewing habits, oral habits such as grinding or clenching, and poor head and neck posture, and also names psychological tension as an important factor. So the core of treatment is to reduce pain while finding and reducing contributing factors in daily life one by one.

Published 2026-11-08 · Updated 2026-11-08 · DentalStatics editorial team

Key facts

Structure of causes	Several contributing factors overlap rather than a single cause (source: Korea Disease Control and Prevention Agency (KDCA))
Classification of contributing factors	Biological, behavioral, environmental, social, emotional and cognitive factors (source: Korea Disease Control and Prevention Agency (KDCA))
Examples of behavioral factors	Grinding, biting nails or lips, gum chewing, tongue thrusting, mouth breathing, cradling a phone on the shoulder (source: Korea Disease Control and Prevention Agency (KDCA))
Examples of biological factors	Skeletal abnormality, past jaw injury, forward head posture, hypothyroidism, etc. (source: Korea Disease Control and Prevention Agency (KDCA))
Age and sex most often treated	People in their 20s are the largest group, and women are about 1.5 times men (2015) (source: Ministry of Health and Welfare (analysis by the National Health Insurance Service))

Why is it hard to name a single cause of TMJ disorders?

The jaw joint is used countless times a day for talking, chewing and swallowing, so small strains that build up over a long time can exceed the limit the joint and muscles can bear. The KDCA sees this accumulating chronic tissue fatigue and microscopic damage as the main cause of TMJ disorders.

The reason one person gets symptoms and another does not, even with the same habit, is that other factors such as skeletal structure, muscle condition and stress level act together. So in TMJ care, rather than looking for one cause, the dentist lists the contributing factors that overlap in that person.

Which daily habits strain the jaw joint?

The behavioral factors named by the KDCA and the National Health Insurance Service (NHIS, 국민건강보험공단) are mostly things you can notice and change yourself in daily life. Grinding and clenching in particular can go on for a long time without your knowing, during sleep or while concentrating, so they are the first things to check.

Grinding, and clamping the teeth when tense
Biting nails, lips or objects like pens, and chewing gum for a long time
Chewing on one side only, opening the mouth too wide
Resting the chin on a hand, cradling a phone between chin and shoulder on calls
Irregular meals and too much caffeine

How do posture and physical factors affect the jaw joint?

A posture with the head forward of the shoulders keeps the muscles around the neck and jaw tense and can increase strain on the jaw joint. Looking down at a computer or phone for long periods and sitting tilted to one side are also checked for the same reason.

Biological factors mentioned include imbalance in the jawbone or tooth alignment, past jaw injury, a genetic tendency, hypothyroidism, a lack of female hormones and certain systemic diseases. These are hard to change right away, but clinicians take them into account when deciding on a treatment direction.

The KDCA also names environmental factors such as vibration, noise, poor lighting, excessive monitor use and allergies as contributing factors. If you cannot change your work environment right away, start by stretching the neck and shoulders during every break and setting the screen height to eye level.

What role do stress and emotions play?

Stress such as conflict at home or work, financial difficulty and major loss acts less as a direct cause and more as a factor that worsens pain. When tense you clench your teeth without realizing it, and the chewing muscles cannot rest, so pain can last longer.

The KDCA explains that long-lasting anger, anxiety and depression can raise muscle tension and reduce participation in treatment. Confusion from conflicting information is also named as a cognitive factor that lowers the motivation to be treated, so it helps to set clear treatment goals with a trustworthy clinician.

How does knowing the cause change TMJ treatment?

If the contributing factor is grinding, a splint and habit correction are central to the treatment plan; if posture, neck and shoulder exercises and adjusting the work environment; if stress, behavior therapy and relaxation training. Reducing these factors alongside lowering pain with medicine or physical therapy is what prevents recurrence.

The KDCA describes the core of TMJ disorder treatment as finding and removing multiple contributing factors. Writing down your habits and daily patterns before a TMJ visit makes finding the contributing factors much faster.

Common myths and facts

Myth: TMJ disorders come only from teeth that do not bite together properly.

The KDCA sees TMJ disorders as the result of several overlapping contributing factors. Habits, posture, stress and general condition act together.

Myth: Stress has nothing to do with jaw pain.

Stress, anxiety and depression are named as factors that raise muscle tension and lower participation in treatment, worsening pain.

Myth: Chewing lots of gum trains the jaw muscles and is good.

The habit of chewing gum for a long time is named as a behavioral factor that strains the jaw joint. When your jaw hurts, it is better to cut back on gum.

Frequently asked questions

Why are TMJ disorders common in people in their 20s?

In the 2015 health insurance analysis, people in their 20s were the largest group treated, and the KDCA also explains that symptoms increase from the teens to the 30s and then decline. A single cause has not been identified, so it is important to check your own contributing factors regardless of age.

Is there a reason TMJ disorders are more common in women?

Women were about 1.5 times men among health insurance patients, and the KDCA mentions a lack of female hormones as one of the biological factors. However, it is hard to explain with a single reason.

Does orthodontic treatment cause TMJ disorders?

TMJ disorders arise from several overlapping contributing factors, so it is hard to pin it on one treatment. If jaw pain or noise appears during orthodontic treatment, tell your dentist and check it together.

Will jaw pain improve if I cut back on coffee?

The KDCA names excessive caffeine intake as a behavioral contributing factor. If you drink a lot of coffee, cut back the amount while managing other habits too, and watch for changes.

I injured my jaw before. Can a TMJ disorder develop later?

A past jaw injury is named as one of the biological contributing factors. If opening the mouth or chewing changed after the injury, tell your dentist about that history.

References

Korean version →