The channelization of upper and lower anterior face heights compared to population standard in males between ages 6 to 20 years

The upper and lower face heights of 120 males with complete longitudinal records at the ages 6 to 20 years (obtained from the Burlington Growth Centre, Toronto, Canada) were studied longitudinally. Population standards were established on a percentile basis using data available for the total sample. Percentile plottings were made at 6, 9, 12, 14, 16, 18 and 20 years. Individual growth curves were compared to percentile population curves and the channelization of the upper and lower face height was assessed. In 22 cases with high or increasing lower face height, the size of the airway through the nasopharynx and the nose was assessed on profile and postero-anterior cephalograms respectively. Correlation analyses were carried out for the upper and lower face height and different facial variables. The variances of upper and lower face height were compared. Both the upper and lower face height did not channelize in many cases, in the majority of the cases with increasing lower face height the airway through the nasopharynx and/or the nose was narrow. No correlation was found between upper and lower face height. The variance in the lower face height was three times that of the upper face height. The upper and lower face height are highly independent variables. The lower face height is a highly independent variable with greater variance in dimension than the length of the maxilla and the mandible. The dimension of the lower face height seems to be more dependent on muscle function, environmental factors interfering with the airway and the posture of the head.