Effect of unilateral injection of botulinum toxin on lower facial contouring evaluated by three-dimensional laser scan

Abstract

Many patients want to make their hypertrophic masseter muscle slim to reduce a prominentmandibular angle. Surgical reduction has become known widely in the past, but bilateralbotulinum toxin injection in masseter muscle which offers a less invasive approach thansurgical reduction becomes the center of public interest in an alternative treatment forhypertrophic masseter muscle. The aim of this study is to measure the volume and thicknesschange in unilateral hypertrophic masseter muscle with unilateral botulinum toxin type Ainjection using 3D laser scanning unlike former bilateral injection treatment for bilateral masseter muscle hypertrophy. The volume and thickness of lower facial contour of 10 unilateral hypertrophic masseter muscle patients were measured with 3D laser scan before 25 units of botulinum toxin type A injected unilaterally. In same way, the volume and thickness of lower facial contour was measured 4, 8, 12 weeks after injection and superposed 3D laser scan of before injection, and then changed volume and thickness were determined. While not injected side showed little change, mean values of the volume and thickness of injection side at each time point diminished obviously between preinjection and 4, 8, and 12 weeks after postinjection and showed statistically significant difference. Unilateral Botulinum toxin type A injection diminished the volume and thickness of unilateral hypertrophic masseter muscle significantly. Consequently it is considered that unilateral botulinum toxin type A injection is very helpful to the esthetic treatment for muscle induced facial asymmetry patients.