Retrospective Three-dimensional facial soft tissue analysis in skeletal Class I malocclusions with premolar extractions

Abstract

Objectives: Decreased volume and atrophy are hallmarks of aging facial soft tissues. In perioral region, a hallmark is deepening of nasolabial folds. It is unknown how extraction orthodontic treatment affects such tissues. This study describes nasolabial fold regional changes in premolar extraction cases. Methods: Pre- and post-treatment 3dMD images of 14 skeletal Class-I patients with 4 premolar extractions were studied for changes of tissue thickness in the nasolabial fold region. All subjects were treated at Temple University. The sample consisted of 10 females and 4 males aged 12 -26 years old and included three ethnicities: Asian, Hispanic, and African American. With the aid of 3dMD Vultus software, both qualitative and quantitative analyses were collected. Color histograms were created for qualitative analyses, and quantitative volumetric changes in cheek volume were correlated to 2-D cephalometric lip thickness, lip retraction, and incisor retraction. Data were analyzed by Spearman’s rho for lip thickness, lip retraction, and incisor retraction. Regression analyses were completed controlling for age, gender, and ethnicity. Results: In this sample of Class-I malocclusion patients with 4 premolar extraction treatment, quantitative results showed no significant correlations were found between 2-D soft tissue thickness and volumetric changes around the nasolabial fold region. Moreover, none of the other characteristics including, change in the upper lip in 2-D cephalometric measurements, age, and gender were factors that correlated with volumetric changes around the nasolabial fold. The qualitative findings showed changes in lips and commissures did not affect the soft tissues around the nasolabial fold areas. Overall, there were no significant correlations between the thickness of soft tissue, change in the lips in 2-D, age, ethnicity, and gender in volumetric changes. Conclusions: Data generated by this investigation did not imply any cause-and-effect relationship between measurements of lip thickness, lip retraction, and incisor retraction to the deepening of the nasolabial fold.