Quantitative dynamic analysis of the nasolabial complex using 3D motion capture: A normative data set

Smile reanimation should be considered from a dynamic perspective. Any intervention should restore normality. To date no such normative dynamic data has been published.

To quantitatively analyse maximal smiles between a healthy group of Caucasian male and female adults using 3D motion capture (4D stereophotogrammetry).

Using a 3D facial motion capture system 54 males and 54 female volunteers were imaged whilst performing a maximal smile. Eight nasolabial landmarks were digitised and tracked. Differences in displacement and speed of bilateral landmarks between males and females were analysed in each direction (x, y, z and Euclidian), from rest (T₀), to median smile (T₁) and maximal smile (T₂), using paired t-tests and Wilcoxon-Signed Rank tests.

In males and females the displacement and speed of the left and right alar base landmarks were similar in the x and y directions but less in the z direction. For the philtrum, the displacement and speed of the bilateral landmarks were similar in the y and z directions, but less in the x direction. The left alar base and left philtrum moved significantly more in males. Left and right cheilion moved a similar amount in the x and y directions but more in the z direction. Labiale superius moved significantly more in the z direction, and labiale inferius moved significantly more in the y direction in males. In conclusion, this study has presented a novel normative data set of dynamic nasolabial complex movement for males and females during maximum smile. The data, as well as providing magnitudes of displacements of the nasolabial complex, also provides the speeds of movement.