Effect of an oral appliance on lower facial contouring after botulinum toxin type A injection, assessed using three-dimensional laser scanning

Abstract

This study used three-dimensional (3D) laser scanning to determine the effect of an oral appliance on changes in the external lower facial contour after injecting botulinum toxin type A (BTX-A) into the human masseter muscle. Fifteen volunteers were enrolled in this study. Twenty-five units of BTX-A was injected at two points at the center of the lower one-third of the masseter muscle, bilaterally. The clinical effect of BTX-A was evaluated by 3D laser scanning before the injection and 4, 8, 12, and 24 weeks thereafter.The subjects wore an anterior bite plane splint (ABS) during the night from 4 to 12 weeks after BTX-A injection. Mean data for the volume and the bulkiest height differed significantly between preinjection and 4, 8, 12, and 24 weeks postinjection both with and without with the ABS. The use of an ABS during the night from weeks 4 to 12 was ineffective as a supplementary treatment for masseteric hypertrophy after BTX-A Injection. However, the volume of the lower face recovered more slowly in the ABS group than in the non-ABS group over the 24-week postinjection follow-up period. Therefore, future studies should determine the most effective application time for an occlusal splint and to compare the ABS with a full- arch occlusal splint. Furthermore, prospective long-term studies involving larger numbers of subjects of both genders after BTX-A Injection are required.