Evaluation of maximal mouth opening for healthy Indian children: Percentiles and impact of age, gender, and height

BACKGROUND AND AIM Maximal mouth opening (MMO) is used as a marker of masticatory pathology. However, MMO among children varies considerably with their age, height, sex, and race. While accurate percentile of normal mouth opening and relationship with anthropometric measurement are not precisely defined for the Indian population, we designed prospective, observational study to define the percentiles for normal MMO in our children. METHODS A total of 985 children, 560 males and 425 females, in the age range of 5-18 years attending the pediatric clinic in a tertiary care center in Western India were studied. In addition to the basic demographic data, MMO was measured in these children. The children were asked to open their mouth maximally until no further opening was possible. The distance from the incisal edge of the upper incisor teeth to the incisal edge of the lower incisor teeth was measured using a calibrated fiber ruler. Statistical analysis was performed to assess the impact of other anthropometric measures such as age, gender, and height on MMO. OBSERVATIONS The mean MMO for males was 44.24 (±5.84) mm and for females was 43.5 (±5.19) mm. Age- and height-related percentiles were created for girls and boys separately, showing the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles from 5 through 18 years of age with 86-185 cm height. CONCLUSION The MMO percentile range for different age and height groups is established for the normal children. The mouth opening seems to increase with the age and especially with the height as per the skeletal growth. Height affects mouth opening more than the age.