Temporomandibular joint disorder

Japanese: 顎関節症 - がくかんせつしょう（英語表記）Temporomandibular disorder

What is the disease?

Chewing ( Chewing ) Dysfunction of the masticatory muscles (the muscles that move the jaw) causing pain or discomfort when chewing or opening and closing the mouth. Temporomandibular joint ( Educational experience ) The limited mobility accompanied by pain and noise in the jaw joint is collectively called temporomandibular joint disorder. These symptoms may appear alone, but in many cases, the two symptoms coexist.

What is the cause?

Temporomandibular joint disorder is a multifactorial disease, and causes include mental stress, lifestyle habits that accumulate fatigue, and abnormal bite alignment, but teeth grinding and clenching are thought to have the greatest direct impact. In other words, if you have the habit of grinding or clenching your teeth, fatigue accumulates in the chewing muscles and at the same time, excessive strain is placed on the temporomandibular joint, which can ultimately lead to jaw dysfunction (inability to open the mouth, inability to chew hard foods, etc.) accompanied by pain in the chewing muscles and temporomandibular joint.

The incidence rate is said to be about 10% of all dental patients, and it is said to be more common in women in their 20s to 40s, but recently the number of younger patients has been increasing.

How symptoms manifest

The main clinical symptoms are muscle pain during jaw movement (when moving the jaw), pain and noise in the temporomandibular joint (the area in front of the ear), etc. In many cases, these symptoms are combined.

Testing and diagnosis

Diagnosis is based on detailed medical history, clinical findings, and plain X-rays. Depending on symptoms and treatment history, special imaging tests such as MRI, CT, and temporomandibular joint arthroscopy may be performed.

In particular, if the treatment process is prolonged, the differential diagnosis with other diseases (malignant tumors may be lurking behind the symptoms of temporomandibular joint disorder) should be reconsidered.

Treatment methods

80-90% of patients with temporomandibular joint disorder can improve their symptoms with non-surgical treatment (massage and stretching of the chewing muscles, treatment with mouthpieces, drug therapy, etc.). As a general rule, irreversible treatments such as grinding down teeth or adjusting them with crowns should be avoided just because the bite is misaligned.

For pain in the temporomandibular joint that does not respond to non-surgical treatment, TMJ lavage therapy is applied to wash out inflammatory substances in the joint. If this is also ineffective (1-2% of cases), we consider applying open temporomandibular joint arthroplasty to reshape the deformed bone and articular disc.

What to do if you notice an illness

If you have any symptoms that seem to be related to your teeth, please consult your dentist or oral surgeon.

Yoshiki Hamada

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　咀嚼(そしゃく)（物を噛むこと）したり、口を開閉する際に、咀嚼筋（あごを動かす筋肉）に痛みや違和感を感じる咀嚼筋群の機能障害と、顎関節(がくかんせつ)の痛みや雑音を伴う可動制限を総称して顎関節症と呼びます。これらは、単独で症状を現す場合もありますが、多くは両者が混在した病状を呈します。

原因は何か

　顎関節症は多因子的疾患で、精神的ストレス、疲労を蓄積させる生活習慣、噛み合わせの異常などがあげられますが、直接的には、歯ぎしりや食いしばりによる影響が最も大きいと考えられます。つまり、歯ぎしりや食いしばりの習癖があると、咀嚼筋に疲労が蓄積されると同時に、顎関節にも過剰な負担がかかり、結果的に咀嚼筋や顎関節の痛みを伴う顎機能障害（口が開かない、硬いものが噛めないなど）に至ると考えられます。

　発症頻度は、歯科受診患者総数の約10％とされ、20～40代の女性に多いといわれていますが、最近では若年者の患者が増加しています。