Reduced mouth opening- Should you be worried?

Written by Dr. Apurva Chavan

October 26, 2020

You may often have experienced you mouth is unable to open properly when your dentist asks you to open your mouth wide. Or even when you want to take a large bite of your burger you once did. Reduced mouth opening is when you can’t open your mouth completely. Normal mouth opening is around 40-50 millimeters.

A trismus or lock jaw is when the mouth opening is just 35 millimeter or less and associated with pain. This condition is definitely serious and needs attention from your dentist.

TMJ disorders lead to reduced mouth opening

The TMJ or the jaw joint is responsible for the opening and closing of your mouth. Any kind of injury to this joint could limit your jaw opening.  Factors like external injury, displaced disc due to excessive movements, muscle injury, night grinding or clenching  of teeth or even arthritis can cause damage to the TMJ. So do not ignore the clicking sounds coming from your jaw, as it could mean a TMJ disorder.

Pre cancerous lesions

Precancerous lesions like Oral submucous fibrosis (OSMF) cause reduced mouth opening.  The causative agent of OSMF is excessive consumption of tobacco or beetle nut products, which irritates the mouth. Oral tissues when irritated for a long period of time, undergo fibrosis and inflammation to form stiff bands. These bands restrict the opening of the mouth. If bad habits are continued, OSMF could turn into cancer.

Space infections

Space infection is a serious condition that causes a facial swelling, pain, fever and could limit the opening of your mouth. It usually start from a long decayed tooth, then spreads into your bone and soft tissues. It is usually characterized by the inflammation of your sub maxillary or submandibular spaces which reduces your mouth opening. So do not ignore decayed teeth for long as they can turn into a space infection.

Wisdom teeth

Pericoronitis is the inflammation and swelling of the area around the wisdom teeth. It is usually seen before or during eruption of wisdom teeth and it often causes reduced mouth opening.  Sometimes you may even experience resisted mouth opening after a wisdom tooth extraction.

This could be because of the bone cutting done during a surgical extractions or the extensive mouth flexion done during the removal. Reduced mouth opening in both of these cases is transient and goes usually goes away on its own.

Radiation for head and neck cancer

Oral cancer, especially of the jaw often requires radiation therapy.  This therapy can be too strong for some people and could cause limited mouth opening. Radiation causes scar tissue formation around the muscles of mastication and the TMJ. This leads to reduced mouth opening in about 10-40% of the cases. As of now there is no remedy for the reduced mouth opening caused due to radiation therapy.

Reduced mouth opening causes a lot of problems like pain while opening the mouth and chewing hard things. Difficulty in talking, chewing and brushing is also commonly seen.

Treatment options for reduced mouth opening

Reduced mouth opening when diagnosed early could save you from further consequences.


Your dentist may prescribe a pain killer, muscle relaxant or anti-inflammatory medication.  In some cases your dentist may even inject anti-inflammatory or steroidal drugs to control the swelling if it’s very severe.

Physical therapy

Physical therapy involves the opening of your jaw with jaw exercises and massaging. Some of them are assisted by your dentist and some can even be done by you at home. E.g. chewing gum.

Jaw stretching devices

If medications and physical therapy are not helping then your dentist may use a jaw stretching device to open your mouth. These devices slowly open your mouth up to 5 to 10 millimeters.

Surgical intervention

Certain cases like OSMF need surgical correction by cutting of the fibrous bands. Other cases like damaged or ankylosed TMJ, tumors, fractured jaw etc. also require surgery.

So do not ignore reduced mouth opening and seek medical attention at the earliest. Brush your teeth twice a day and floss regularly to maintain oral hygiene and avoid infections.

What is your Oral Type?

Everybody has a different oral type.

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