What is the normal range for mouth opening in millimeters?

The normal range for mouth opening, often assessed during a physical examination, typically falls between 40 to 60 millimeters. A value of 40 mm is commonly cited as a representative minimum value for normal range, highlighting that individuals may comfortably open their mouths wider, but any measurement below this threshold may indicate potential limitations or issues such as temporomandibular joint dysfunction. Therefore, the choice specifying 40 mm aligns with the accepted range and reflects the typical anatomical capacity for opening the mouth without discomfort or restriction. This assessment is crucial in evaluating a patient's oral health and functional capabilities.