Effect of Botulinum Toxin Injection on Asymmetric Lower Face with Chin Deviation

Unilateral injection of botulinum toxin type A into the masseter muscle induces mandibular asymmetry in adolescent rats by suppressing the angular process growth

INTRODUCTION

Mandibular asymmetry has negative impacts on maxillofacial aesthetics and psychological well-being. This study investigated the effects of unilateral injection of botulinum toxin type A (BTX-A) into the masseter muscle on mandibular symmetry.

METHODS

Forty Wistar rats (4-week-old) were divided into 4 groups (n = 10): control, group 1 (1U BTX-A), group 2 (3U BTX-A), and group 3 (1U BTX-A for 3 times). BTX-A was injected into the right masseter of treatment groups. Cone-beam computerized tomography scans were taken before the injection and then at 2 weeks, 4 weeks, and 6 weeks after injection. Histologic and immunohistochemical staining were done for the condylar cartilage. RNA sequencing and quantitative reverse transcription polymerase chain reaction were used to detect gene expression in the angular process.

RESULTS

In Groups 2 and 3, the right angular process length and the ramus height were reduced 4 weeks after injection, resulting in the mandibular midline deviating to the right side; the right condylar cartilage had reduced thickness and decreased expression of RUNX2, SOX9, and COL II (P <0.05). Two hundred sixty-one genes were differentially expressed (256 downregulated) in the angular process at 3 days post-BTX-A injection, and the calcium signaling pathway was unveiled through the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Furthermore, TRPC1, Wnt5a, CaMKII, Ctnnb1, and RUNX2 expression were significantly downregulated at 1 and 3 days postinjection.

CONCLUSIONS

Unilateral injection of BTX-A into the masseter muscle in adolescent rats induces mandibular asymmetry by suppressing the angular process growth on the injected side.

Cosmetic Treatment Using Botulinum Toxin in the Oral and Maxillofacial Area: A Narrative Review of Esthetic Techniques

Botulinum toxin (BoNT) is an anaerobic rod-shaped-neurotoxin produced by Clostridium botulinum, that has both therapeutic and lethal applications. BoNT injection is the most popular cosmetic procedure worldwide with various applications. Patients with dynamic wrinkles in areas such as the glabella, forehead, peri-orbital lines, nasal rhytides, and perioral rhytides are indicated. Excessive contraction of muscles or hyperactivity of specific muscles such as bulky masseters, cobble stone chins, gummy smiles, asymmetric smiles, and depressed mouth corners can achieve esthetic results by targeting the precise muscles. Patients with hypertrophic submandibular glands and parotid glands can also benefit esthetically. There are several FDA-approved BoNTs (obabotuli-numtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, letibotulinumtoxinA, prabotulinumtox-inA, daxibotulinumtoxinA, rimbotulinumtoxinB) and novel BoNTs on the market. This paper is a narrative review of the consensus statements of expert practitioners and various literature on the injection points and techniques, highlighting both the Asian and Caucasian population separately. This paper can serve as a practical illustrative guide and reference for optimal, safe injection areas and effective doses for application of BoNT in the face and oral and maxillofacial area. The history of BoNT indications, contraindications, and complications, and the merits of ultrasonography (US)-assisted injections are also discussed.

Bell felcinin viral patojenitesi ve tedavi olarak botulinum toksin tip A kullanımı

Bell'in felci, kraniyal sinir VII'nin iltihaplanmasının ortak adıdır. Kendine özgü genikulat ganglion iltihabı idiyopatiktir ve hemifasiyal felce neden olur. Bu felçten muzdarip olan hastaların semptomları 3 hafta ile 3 ay arasında kaybolabilir. Yüz felci devam eden bazı hastalar için botulinum toksin tip A etkili bir tedavi olabilir. Kas felcinin şiddetine göre botoksun yanı sıra ameliyat, steroid ve antiviral tedavi gibi farklı tedaviler sunulabilir. Bu derleme makalesinin amacı, viral patojenlerin fasiyal sinir iltihabının aktivasyonu ile olası ilişkisine ve Bell felçli hastaların tedavi olarak botoks tip-A'dan nasıl yararlanabileceğine dalmaktır.

One-Half Wedge Osteotomy Genioplasty for Correction of Chin Deviation Based on Three-Dimensional Computed Tomography Measurements and Simulation

ABSTRACT

Conventional operations correcting chin deviations mainly rely on the observation and experience of the surgeons during the operation. We have created a new surgical method, one-half wedge osteotomy genioplasty (1/2WOG), that combines three-dimensional computed tomography measurements and simulation. This study evaluated the clinical effect of chin deviation correction with the 1/2WOG method. A total of 38 patients (15 men and 23 women) who underwent 1/2WOG between October 2019 and October 2014 were evaluated. The chin deviation angle and distance, and partial chin deformity were measured preoperatively using three-dimensional computed tomography data. Precise calculations and osteotomy lines were achieved by preoperative simulation. All patients underwent the same surgery by the same surgical team. The clinical effect of 1/2WOG was evaluated according to the preoperative and postoperative data and patient satisfaction. All 38 patients achieved satisfactory aesthetic results without major complications such as chin nerve injury or bone nonunion. Eight patients occured numbness of the lower lip after surgery; at 6-month follow-up, the numbness was reduced in 2 patients and disappeared in 6 patients. Compared with preoperative data, the chin deviation angle, chin deviation distance, and gonion-menton difference were significantly reduced postoperatively. During the 12-month follow-up, the patient satisfaction rate reached 90%. We conclude that chin deviation can be improved by 1/2WOG. The combination of digital technology measurements and simulation can increase the accuracy of the osteotomy line design, thus reducing surgical trauma and increasing patient satisfaction, which is worthy of clinical promotion.