Association between Oral Function and Soft Tissue Facial Type in Japanese Elementary School Children

This study aimed to investigate the relationship between facial morphology and oral function among schoolchildren, utilizing measurements such as the facial index, tongue raising force, occlusal force, and lip closure force within a general population. A total of 143 third- and fourth-grade elementary school students（77 boys and 66 girls）participated in the study. The facial index（posterior facial height/anterior facial height）was computed from photographs of the right side of each participant’s face. Among the subjects, those with a facial index falling below or exceeding 1 S.D. from the mean were categorized as long-faced（12 boys, 12 girls）or short-faced（15 boys, 10 girls）, respectively. Oral function tests were conducted by measuring tongue raising force, occlusal force, and lip closure force three times each, and the mean values were calculated. Comparison between long-faced and short-faced subjects revealed a significant discrepancy in occlusal force among boys and girls, with short-faced subjects exhibiting greater values compared to the long-faced subjects. While girls exhibited similar tendency as boys in terms of occlusal force, no significant differences were found across all parameters. Correlation analysis unveiled significant positive correlations between the facial index and occlusal force, occlusal force and tongue raising force, and tongue raising force and lip closure force. In conclusion, a significant correlation was identified between occlusal force and vertical facial morphology. Long-faced individuals tended to demonstrate weaker occlusal force, while short faced individuals exhibited stronger occlusal force.