The normal range of maximal incisal opening in pediatric population and its association with physical variables.

Restricted mouth opening is a common complaint in patients suffering from temporomandibular joint disorders, ankylosis, impaired masticatory muscle function, rheumatic disease, infection, or malignancy. As with any disease, the aim of treatment of disorders affecting mouth opening is to restore the mouth opening to its normal value. It is thus of paramount importance to determine the normal value.To establish the normal range of maximal incisal opening (MIO) in children aged 4 to 15 years and to investigate the correlation between MIO and age, gender, height, and body weight.Six hundred and two children from various schools in Bengaluru, India, participated in the study. The children were divided into the following age groups: 4-5, 6-7, 8-9, 10-11, 12-13, and 14-15 years. MIO for the children was recorded using Therabite scale. The measurements of MIO were then correlated with gender, body weight, and height of the children in different age groups.It was observed that MIO gradually increased with age with a mean MIO of 41.34 mm at 4-5 years to a mean MIO of 51.73 mm at 14-15 years. The mean MIO value for males (48.90 ± 6.49 mm) was found to be higher when compared to that of females (46.17 ± 5.58 mm). The results indicated a strong positive correlation of MIO with height and weight.MIO gradually increased with age in both the genders, and a strong positive correlation of MIO with height and weight was observed.