A Novel Intraoral Technique for Botulinum Toxin Type A Application in the Mentalis Muscle.

The mentalis muscle plays a critical role in lower facial balance by stabilizing the lower lip and shaping the chin contour. Botulinum toxin type A (BoNT-A) is commonly used to manage excessive mentalis activity; however, inaccurate injection techniques may lead to functional impairment and undesirable aesthetic outcomes. This technical report describes a novel and innovative intraoral botulinum toxin injection technique targeting the mentalis muscle based on precise anatomical localization of its origin. The proposed method introduces a new intraoral approach designed to improve injection accuracy while minimizing toxin diffusion and preserving lower lip function. A detailed anatomical assessment was performed to define the muscle's origin, fiber orientation, and relevant surface landmarks, which informed the development of a controlled injection strategy emphasizing precise depth and placement. In clinical application, the technique was performed in three patients, demonstrating consistent modulation of mentalis contraction, improvement in chin surface appearance, and preservation of lower lip function without functional compromise. This new and reproducible technique highlights the importance of anatomical precision in BoNT-A injection planning and provides a practical framework to enhance safety and aesthetic outcomes in treatments of the lower third of the face.