Depressor labii inferioris muscle palsy after chin augmentation

The depressor labii inferioris (DLI) muscle helps to lower and turn the lower lip outward and receives innervation from the marginal mandibular branch of the facial nerve. Paralysis of this muscle is a rare but potential complication of chin augmentation injections. Paralysis of the DLI causes symptoms such as difficulty smiling on the affected side, difficulty speaking clearly, and facial asymmetry, especially when smiling. In this case report, we present two female patients, aged 29 and 36 years, who were evaluated for impaired lower lip movement, asymmetry in smiling, and slurred speech following submandibular liposuction and chin augmentation. The patients were found to have DLI palsy, closely followed with facial exercises, and recovered completely within three months. Although isolated DLI palsy is rare, it may occur as a complication of various maxillofacial surgeries. Careful technique and good knowledge of facial anatomy are important to prevent complications.