The use of botulinum toxin type A in aesthetic mandibular contouring.

The lower third of Asian faces is wider than that of Caucasians and it is determined by the size and width of the mandibular bone and the thickness of muscles and subcutaneous fat tissues surrounding it. Efforts to create an aesthetically slim and smooth facial contour line in nonobese people have led the authors to focus on two approaches: surgical resection of the masseteric muscle and modeling ostectomy of the square-angled mandibular bone. Because these procedures present some problems, the authors adopted a nonsurgical concept that chemically denervates muscles and reduces the bulk of the muscle. The authors have conducted a total of 1021 clinical cases from March of 2001 through September of 2002, in which patients were treated with botulinum toxin type A (Dysport; Ipsen Ltd, Slough, United Kingdom) for remodeling the lower facial contour line; 383 of those cases were followed up for at least 3 months after the initial injection. A database was made by measuring the change in the thickness of the injected muscle with an ultrasonogram. Eleven patients underwent resection of the mandibular angle before injection. The preinjection ostectomy group was involved in the study as a result of their dissatisfaction with the surgical results; they had a rather thick masseter muscle and not a bone problem. Some had both bone problems and a thick masseter muscle. Three months after the botulinum toxin injection, the thickness of the muscle was reduced by 31 percent on average. The atrophic effect of injection was observed after 2 to 4 weeks for most patients. Seventy percent of the 383 patients tracked were greatly satisfied with the result, with another 23 percent generally satisfied. No long-term side effects were reported. Masseteric hypertrophy is frequent in Asians because of racial characteristics and dietary habits. Botulinum toxin type A has made a new epoch in facial contouring for Asians. Considering that Asians have a prominent malar and a prominent mandible angle, the reduction in the thickness of the masseter can provoke relative prominence of the malar and mandible angle. Therefore, precise indication and anatomy of the facial muscle should be thoroughly understood, which will decrease the incidence of side effects and problems. Botulinum toxin type A (Dysport) injection is simple in technique, has few side effects, and promises a rapid return to daily life. The authors conclude that the injection of botulinum toxin type A can replace surgical masseter resection.