Posted by Sarah Schuman, M.S. CCC-SLP on 11/11/2021 to General Medical and Dental Information
Mouth opening is measured as a MIO or ROM distance. MIO (maximal interincisal
opening) is the distance between the central incisors when the mouth is fully open.
Average MIO for adults is approx. 50mm. By measuring MIO, a therapist can determine
if a patient is WNL or has trismus. ROM (Range-of-Motion) is the maximum distancethe mandible moves. ROM and MIO may be different, e.g. patients with an open bite.