The time-course change in the lip closing force in Class III malocclusion after orthognathic surgery

ObjectivesThe purpose of this study was to examine the changes with time in lip pressure after orthognathic surgery for skeletal Class III patients.Study designThe subjects consisted of 63 patients (32 female and 31 male) diagnosed with mandibular prognathism who underwent sagittal split ramus osteotomy with and without Le Fort I osteotomy. Maximum and minimum lip closing forces were measured with Lip De Cum®. The changes with time were compared statistically.ResultsThe maximum and minimum lip closing force increased time-dependently in men and women after surgery and there were significant differences between men and women with changes with time in the maximum lip closing force (p = 0.0086) and the minimum lip closing force (p = 0.0302). After 1 year, the Class III group maximum lip closing force was significantly smaller than the control group in both men (p < 0.0001) and women (p < 0.0001).ConclusionsThis study suggests that there was significant difference in over time in the lip closing force between men and women in Class III patients. Although the maximum lip closing force increased with time, it did not reach the level of the control group after 1 year.