Ultrasound dimensional changes of the anterior belly of the digastric muscle induced by orthognathic surgery and botulinum toxin A injection in Class II malocclusion

• DOI: 10.1007/s11282-020-00502-6
• Publication Date: 2021-01-09T13:05:11Z
• Authors: Alina Coclici; Raluca Ancuta Roman; Simion Bran; Emil Crasnean; Mihaela Baciut; Cristian Dinu; Mihaela Hedesiu
• Keywords: 03 medical and health sciences; 0302 clinical medicine; Muscles; Orthognathic Surgery; Humans; Botulinum Toxins, Type A; Malocclusion, Angle Class II; Ultrasonography

The aim of the study is to evaluate the ultrasonographic dimensional changes of the anterior belly of the digastric muscle (ABDM), occurring after intramuscular botulinum toxin A (BTX-A) injection during orthognathic surgery, in a series of five Class II malocclusion patients.All the patients received 20 units of BTX-A, into both ABDM, intraoperatively. The length, width and cross-sectional area (CSA) of the ABDM were ultrasonographically measured at three different time points: T0 (preoperatively), T1 (postoperatively at 2 weeks after the surgical intervention), and T2 (postoperatively at 6-9 months).A statistically significant higher length of the ABDM was noted postoperatively, at T1 and T2 compared to T0. The patients showed an increased length by 12.2% at 2 weeks postoperatively and continued to increase, reaching 24.6% at 6 months. A decreased width of ABDM by 6.5% at T1 compared with T0 was also found.Postoperative ultrasound (US) follow-up measurements in patients with Class II malocclusion, orthognathic surgery and intraoperative BTX-A injection in the ABDM, showed dimensional changes of the muscle, with elongation and thinning. The muscular modifications were more pronounced at 6 months postoperatively, indicating consistency and potential benefit of using BTX-A in reducing the risk of surgical relapse. Further data on longer-term follow-up and larger number of cases are necessary.