Effect of a second injection of botulinum toxin on lower facial contouring, as evaluated using 3-dimensional laser scanning.

[BACKGROUND] Botulinum toxin type A (BoNT-A) is widely used to improve the lower facial contour.

[OBJECTIVE] To determine the difference in the changes in the lower facial contour achieved with 1 and 2 sessions of BoNT-A injections using 3-dimensional (3D) laser scanning.

[MATERIALS AND METHODS] Twenty volunteers were randomly divided into 2 groups. Group I (n = 10) received a single injection, whereas Group II (n = 10) received 2 sessions of injections, the second being administered 4 months after the first. Each injection comprised of 25 U of BoNT-A and was administered to the masseter muscle bilaterally. Evaluation of the effect of BoNT-A injection was performed using 3D laser scan images obtained before the injection and 6 months thereafter in Group I, and before the first injection and 6 months thereafter in the Group II.

[RESULTS] The mean changes in the volume and thickness in Group I were -1,186 mm and -1.52 mm, respectively; the corresponding changes were -4,072 mm and -3.84 mm in Group II. The reductions were significantly greater in Group II than in Group I.

[CONCLUSION] The administration of a second BoNT-A injection is effective for better aesthetic results for the lower facial contour.