Relationship between changes of facial soft tissue and hard tissue profile in correction of children's mandible retruding by functional appliance / 中华医学美学美容杂志

ABSTRACT

Objective To evaluate the changes of soft tissue and hard tissue in the correction of Class II division 1 malocclusion by functional appliance, and to investigate the correlation between these changes and the mechanism underlying the soft tissue profile changes. Methods A total of 32 cases of developing class II division 1 malocclusion were selected. They were in the spurt or pre-spurt phase of growth and development and treated with functional appliance, the molar relationship was corrected to either Class I or overcorrected Class I occlusal relationship. Soft tissue and hard tissue variables on the cephalograms were selected and analyzed. Firstly, paired t-tests were performed to compare the changes between before and after-treatment. Secondly, those variables that had statistically significant differences were selected and analyzed with the Pearson coefficient of correlation (r) between soft tissue and hard tissue changes. Results All variables had statistically significant differences between before and after treatment except for soft tissue facial angle and basic upper lip thickness, mandible plane angle and position of basic upper bone; Correlations between soft tissue and hard tissue changes were as follows: height of lower lip to Me' and S-Go (r=0.54); soft tissue chin thick and N-ANS (r=0.55); height of upper lip and ii/OLp (r=0.52); inferior sulcus to H-line and ii/OLp (r=0.60), pg/OLp, saggital relationship between upper-and lower-jaw (ss/OLp-pg/OLp) (r=0.47). Conclusion The changes of soft tissues profile results from the change of lower incisors' position, mandible' moving forward and its subsequent changes of facial heights and saggital relationship between upper-and lower-jaws.