Facial reanimation in patients with established facial paralysis remains challenging for reconstructive surgeons, and unfavorable results cannot be prevented to a certain extent. Unfavorable functional and aesthetic results can impair the quality of life. When options in which the contralateral facial nerve is used, such as one-stage or two-stage free muscle transfer, a natural spontaneous smile (truly spontaneous smile) can be achieved. On the other hand, when options in which a nerve other than the contralateral facial nerve is used, such as free muscle transfer with coaptation to the masseter nerve and lengthening temporalis myoplasty, the majority of patients can achieve a spontaneous smile innervated by the trigeminal nerve, i.e., without biting. The awareness of all possible adverse effects characteristic to each reconstructive option is the key to avoiding them, and understanding the consequences of unsuccessful reconstruction provides the foundation for satisfactory planning and personalized approaches to revise the result.
