The Volumetric effect of Botulinum Toxin Type A Injection on Parotid Gland: A Prospective Randomized Controlled Trial

Backgrounds: Botulinum neurotoxin type A (BTX-A) to masseter muscle is a useful tool for the aesthetic narrowing 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 quantitatively analyzed the effect of BTX-A on the parotid glands. Methods: The purpose of this study is 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 that desired facial slimming from among patients that required surgery for a facial bone fracture. Patients undergoing BTX-A injection were prospectively 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 thirty patients were enrolled in this study. Ten patients in the high-dose, eight in the low-dose group, and nine in the control group completed the clinical trial. There were significant changes in each high and low dose groups compared to the control group (p < 0.001, p < 0.001), and in interaction of time and group (p < 0.001). The volume recovery after three months was found with 7.6% in the high-dose group and 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.