Cephalometric predictors of optimal soft tissue profile outcomes in growing Asian skeletal class II subjects treated with twin-block appliance: A retrospective study

Document Type



Dental-oral, Maxillo-facial Surgery


Background: Clark's Twin-Block (TB) functional appliance is commonly used to treat mandibular deficiency in skeletal class II growing patients. There have been no prior research that have examined determinants of a optimal soft tissue profile outcome after TB utilising both subjective and objective assessments of soft tissue profile outcome. Therefore, this study was conducted to identify predictors for favorable soft tissue outcomes after TB appliance.
Methods: A cross-sectional study was conducted with 50 subjects treated with TB equally divided into favorable and unfavorable groups. Soft tissue outcomes after TB were assessed subjectively (panel of orthodontists using Visual analog scale (VAS)) and objectively (via cephalometric soft tissue measurements). Sample obtaining 60% of VAS and normal post-treatment soft tissue measurements were included in the favorable group. Paired and independent sample t-test was used to compare cephalometric measurements within and between the groups. Predictors of favorable outcomes were identified using the logistic regression analysis.
Results: Statistically significant differences in pre-treatment values between favorable and unfavorable groups were observed for SN to mandibular plane angle, anterior facial height, ANB angle, pogonion to nasion perpendicular distance, lower incisor to pogonion distance, upper lip to S and E line distances (p ≤ 0.05) and lower lip to S and E line distances (p ≤ 0.001). Multivariable logistic regression analysis found the decreased value of lower lip to E line (95% CI: 0.142, 0.800) and decreased pogonion to nasion perpendicular distance (95% CI: 1.05, 1.85) to be significantly associated with favorable soft tissue profile outcomes.
Conclusions: Cephalometric assessment is an effective predictor of favorable soft-tissue outcomes after TB appliance therapy. Orthodontists can achieve favorable improvement of the soft tissue profile after TB therapy if patients presented with recumbent lower lip to E line and decreased distance of pogonion from nasion perpendicular at the start of treatment.


Volume, issue, and pagination are not provided by the author/publisher

Publication (Name of Journal)

Minerva Dental and Oral Science