Reduced mouth opening- Should you be worried?


Written by Dr. Apurva Chavan

Medically reviewed by  Dr. Vidhi Bhanushali Kabade BDS, TCC

Last updated May 4, 2024

Written by Dr. Apurva Chavan

Medically reviewed by  Dr. Vidhi Bhanushali Kabade BDS, TCC

Last updated May 4, 2024

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 lockjaw is when the mouth opening is just 35 millimeters or less and is 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 surgical extractions or the extensive mouth flexion done during the removal. Reduced mouth opening in both of these cases is transient and 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 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.

Was this article helpful?

scanO (formerly DentalDost)

Stay Informed, Smile On!

Author Bio: Dr. Apurva Chavan is a dentist by the day and a voracious reader and writer by the night. She loves to fix smiles and tries to keep all her procedures as pain free as possible. Equipped with over 5 years of experience she loves to not just treat her patients but also educate them about dental hygiene and appropriate maintanence routines. After a long day of preserving smiles she loves to curl up with a good book or pen down some of life’s musings. She strongly belives that learning never stops and likes to keep her self updates with all the latest dental news and research.

You May Also Like…


Submit a Comment

Your email address will not be published. Required fields are marked *