Volumetric Changes of the Mid and Lower Face with Animation and the Standardization of 3D Facial Imaging

Goals:

3D photography provides volumetric data and surface topography with sub-millimeter precision, but current methods lack standardization for facial expression and position. For example, smiling can mimic the desired outcomes of a facelift and fat grafting by increasing malar volume while decreasing volume in the jowls. Our goal was to quantify volumetric changes of the mid and lower face caused by facial expression so that we can accurately assess volumetric changes after surgery. Secondarily, we aimed to identify soft tissue landmarks that can be used to detect these changes in facial expression or head position to ensure the standardization of 3D images.

Methods:

3D facial images of 16 subjects performing 22 facial expressions or changes in head position were captured. Variable degrees of animation during smiling and frowning were also evaluated. Volumetric changes of the malar and jowl regions with facial expressions were quantified using a 3D superimposed image subtraction technique. Translation (movement >1 mm) of 14 standard soft tissue surface landmarks was assessed during various facial animations to determine which landmarks can be utilized to standardize 3D images.

Results:

Sixteen of the 22 facial expression studied had a significant effect on malar and/or jowl volume. Significant volume changes were noted with subtle animation during smiling and frowning. During maximal smile, mean excursion of oral commissures was 13.7mm +/- 3.0 and the malar region demonstrated a 17.2mL +/- 5.7 increase in volume, whereas the jowl region demonstrated a 1.7mL+/- 0.9 decrease in volume. During maximal frowning, mean excursion of oral commissures was 7.4mm +/- 2.3. The malar region demonstrated a 3.7mL +/- 2.3 decrease in volume, whereas the jowl region demonstrated a 5.4mL +/- 0.9 increase in volume. In the act of smiling, there was significant volume augmentation of the malar region with small degrees of oral commissure excursion, such that a quarter smile (excursion = 25% of excursion with maximal smile) could induce a volume change equivalent to 75% of maximum smile. The jowl decreases in volume with smiling, but in a linear fashion (a quarter smile yields a volume change equivalent to 25% of a maximum smile). Frowning exhibited the opposite, but similarly significant changes in mid and lower facial volume. A 1mm commissure excursion during smiling can produce 5-10mL of malar augmentation or 2-4mL of jowl augmentation with frowning. We believe these results are related to isometric contraction of mimetic muscles and their influence on fat compartments.

A combination of 5 landmarks (glabella, bilateral cheilion, pogonion and laryngeal prominence) was found to indicate all tested facial expressions which effect mid and facial volumes, with the exception of platysmal straining.

Conclusion:

Most facial expressions will lead to translation of the oral commissures, with even a subtle (1mm) excursion leading to 5-10mL of malar augmentation during smiling or 2-4mL of jowl augmentation during frowning. We identified that the glabella, pogonion, laryngeal prominence, and bilateral cheilion can be used as a referencing system to allow identification of subtle changes in head position and facial expression for standardization of 3D images.