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Upper lip elevation in autonomous maximal smile: A three-dimensional facial imaging study
Ruiting Ren1, Xu Zhang1, Yutong Chen1
1State Key Laboratory of Oral Diseases, National Center for Stomatology, National Clinical Research Center for Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Korean Journal of Orthodontics
|January 23, 2026
Summary
Three-dimensional (3D) facial imaging precisely measured upper lip elevation (ULE) during an autonomous maximal smile (AMS). Findings provide normative references for orthodontic treatment and aesthetic procedures.
Area of Science:
- Orthodontics
- 3D Facial Imaging
- Aesthetic Procedures
Background:
- Three-dimensional (3D) facial images of autonomous maximal smile (AMS) are valuable for creating virtual orthodontic patients.
- Understanding upper lip elevation (ULE) in AMS is crucial for orthodontic applications.
Purpose of the Study:
- To investigate upper lip elevation (ULE) in Chinese adults and adolescents during an autonomous maximal smile (AMS) using 3D facial imaging.
- To establish normative references for ULE in different sex and age groups.
Main Methods:
- 212 Chinese participants (male/female adults/adolescents) underwent 3D facial imaging.
- Measurements included upper lip length (ULL), philtrum length (PL), upper vermilion height (UVH), ULE, and upper lip elevation ratio (ULER).
- Cephalometric analysis assessed maxillary incisor exposure and upper lip thickness.
Main Results:
- Male adults had longer resting ULL than female adults, attributed to longer philtrum.
- Upper lip length in AMS (ULL@AMS) differed significantly between male and female adults.
- Upper lip elevation (ULE) and upper lip elevation ratio (ULER) showed correlations with resting ULL and lip thickness.
Conclusions:
- 3D imaging enabled precise measurement of ULL, ULL@AMS, and ULE across diverse demographic groups.
- This study provides preliminary normative data for ULE in AMS, beneficial for orthodontic and aesthetic treatments.
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