A study of bilabial lip pressure in a normal population

Values for bilabial lip pressure on 1,417 children ranging in age from 5 to 18 years of age are presented. The use of bilabial lip pressure values as a tool in monitoring speech production of children with neuromuscular disease, articulation disorders and cleft lip is discussed. Variations with age, sex, height, weight and malocclusion type are presented with mean average values being 5 to 20% larger than the maximum recordings.

In males, the mean values rose by approximately 5% between the ages of 5 and 7 years, remained fairly constant up to age 11, between 11 and 14 years the mean values more than trebled after which they gradually declined with males aged 18 and over having a mean of approximately 75% of the peak at 14 years. In females, the mean values were similar to males up to age 11 years and also demonstrated a sharp increase thereafter peaking at 14 years. The peak for females was, however, only 60% of the corresponding male value, having doubled in the 11-14 year period in contrast to the males who showed a three fold increase. Females exhibited a decline in mean values afte 14 years of a similar relative magnitude to that of the males.

Correlation with height and weight are presented but regression analysis showed that these factors had little additional influence over and above those of subject age.