Did you know that opening your mouth too wide can sometimes put your jaw joint at risk? For most people, a normal range of opening is about 40 mm—roughly the width of two to three fingers placed vertically between the front teeth. Going beyond this range repeatedly or forcefully can strain the temporomandibular joint (TMJ) and in some cases lead to luxation (when the joint slips out of place).

Hypermobility and the Jaw

Some individuals are more prone to these issues because of Generalized Joint Hypermobility (GJH). This condition means the joints can move beyond the normal limits. The Beighton Score (BS) is a simple nine-point test that clinicians use to assess GJH (Malek et al., 2021).

When the jaw joint is hypermobile, patients may notice:

  • Clicking or popping sounds
  • Jerky or irregular jaw movements
  • Episodes where the jaw feels unstable or even gets “stuck” (Tuijt et al., 2018)

These symptoms can make wide opening, like yawning, biting into a large sandwich, or dental procedures, especially risky.

Practical Tips to Protect Your Jaw

  1. Monitor your opening: Try to stay within the comfortable range (about 40 mm or two fingers).
  2. Support during yawning: Place a hand gently under your chin to avoid excessive stretching.
  3. Modify eating habits: Cut food into smaller pieces rather than taking large bites.
  4. Communicate with your dentist: Let your provider know if you have hypermobility so they can adjust their techniques during dental care.
  5. Practice jaw awareness: Notice when you tend to open wide (e.g., during laughter, stretching) and learn to limit the motion.

Why This Matters

Avoiding extreme movements helps reduce stress on the TMJ and lowers the risk of luxations, especially if you already experience joint hypermobility. A little daily mindfulness can go a long way in protecting your jaw health.

References:

Malek S, Reinhold EJ, Pearce GS. The Beighton Score as a measure of generalised joint hypermobility. Rheumatol Int. 2021 Oct;41(10):1707-1716. doi: 10.1007/s00296-021-04832-4. Epub 2021 Mar 18. PMID: 33738549; PMCID: PMC8390395.

Tuijt M, Parsa A, Koutris M, Berkhout E, Koolstra JH, Lobbezoo F. Human jaw joint hypermobility: Diagnosis and biomechanical modelling. J Oral Rehabil. 2018 Oct;45(10):783-789. doi: 10.1111/joor.12689. Epub 2018 Jul 19. PMID: 29972704.