Related Experiment Video
Updated: May 7, 2026
In situ Compressive Loading and Correlative Noninvasive Imaging of the Bone-periodontal Ligament-tooth Fibrous Joint
Published on: March 7, 2014
Three-dimensional soft tissue changes after simulated protrusion of upper and lower incisors in young adults: an
Julia C Glöggler1, To Mai Pham2, Falko Schmidt2
1Department of Orthodontics, Ulm University, Albert-Einstein-Allee 11, Ulm, 89081, Germany. juliagloeggler@web.de.
Background:
One component of facial aesthetics is a harmonic facial profile. Orthodontic treatment and/or orthognathic surgery can affect the facial profile by influencing the underlying hard-tissue structure. The aim of this study was to improve the prediction of treatment outcomes by evaluating 3D perioral frontal and buccal soft-tissue changes after protrusion of incisors in ten young adults.
Methods:
The participants had neutral occlusion and physiologic incisor inclination. 3D-printed acrylic veneers with thicknesses of 1-4 mm were bonded to the labial surfaces of the upper and lower incisors. 3D face scans with and without veneers were taken to evaluate perioral soft tissue changes using 44 landmarks. Face scans were superimposed at the forehead. Soft-tissue changes were evaluated using linear mixed-effects models.
Results:
Interrelations between simulated incisor protrusion and the resulting soft-tissue changes were statistically highly significant (p < 0.005) and nearly linear. Simulated isolated upper incisor protrusion caused greatest forward positioning of the labrale superius convex [LS-con] landmark-by 0.65 mm per millimetre of veneer thickness. Lower lip displacement at the labrale inferius convex [LI-con] landmark was greatest when both upper and lower incisors were protruded (0.76 mm/mm). The vertical lip displacement rate for simulated upper and lower incisor protrusion was 0.12 mm/mm upward positioning of LS-con and 0.66 mm/mm downward positioning of LI-con. Mixed-effects models revealed that a 1-mm increase in initial lip thickness at the labrale superius reduces soft-tissue displacement by about 8% of the simulated tooth movement.
Conclusions:
Anterior positioning of incisors leads to predictable, direction-specific changes in perioral soft tissues. The magnitude and pattern of soft-tissue responses vary with the combination of upper and lower incisor movement and individual lip thickness. These findings may support clinical planning in orthodontic and/or orthognathic treatments.
