The Volumetric Effect of Botulinum Toxin Type A Injection on the Parotid Gland: A Randomized Controlled Trial

Background: Botulinum neurotoxin type A (BTX-A) to the masseter muscle is a useful tool for the aesthetic narrowing of the width of the lower face. The administration of BTX-A to visible parotid glands is also effective to reduce lower facial width. However, no studies have quantitatively analyzed the effect of BTX-A on the parotid glands. Methods: The purpose of this study was to confirm the impact of BTX-A injection on the parotid gland and to suggest the effective dosage of BTX-A in facial slimming. This study was conducted by selecting patients who desired facial slimming from among patients who required surgery for a facial bone fracture. Patients undergoing BTX-A injection were randomized to high-dose, low-dose, and placebo groups, and different doses of BTX-A for each group were injected into both parotid glands during facial bone surgery. Results: A total of 30 patients were enrolled in this study. Ten patients in the high-dose group, eight in the low-dose group, and nine in the control group completed the clinical trial. There were significant changes in both the high- and low-dose groups compared with the control group ( P < 0.001, P < 0.001), and in interaction of time and group ( P < 0.001). Volume recovery after 3 months was found in 7.6% in the high-dose group and in 4.8% in the low-dose group. Conclusion: BTX-A injection into parotid glands can be an effective treatment option in managing salivary gland enlargement for lower face contouring. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.