Symmetry Restoration at Rest after Masseter-to-Facial Nerve Transfer: Is It as Efficient as Smile Reanimation?

Masseter-to-facial nerve transfer is a highly efficient technique for reanimating paralyzed muscle and has been reported to restore facial symmetry at rest. However, no systematic studies have been performed, and the effects of preoperative droop of the oral commissure on postoperative symmetry at rest have rarely been reported.

The authors retrospectively analyzed 35 patients with masseteric-to-facial nerve anastomosis and assessed the quality and quantity of the dynamic recovery and the oral commissure symmetry at rest. The dynamic and static effects were then compared.

All of the patients' Terzis scores were increased postoperatively, and over half of the patients presented restored symmetric smiles (Terzis scores of 4 or 5). The postoperative symmetry scale of the oral commissure at rest improved in 18 of 35 patients. Both the mean postoperative altitude difference of oral commissure excursion and the postoperative altitude difference of bilateral oral commissure position were decreased compared with preoperative values. The preoperative symmetry had a significant effect on the postoperative altitude difference of the bilateral oral commissure position. The effects of the dynamic and static symmetry improvements were transformed to a comparable factor α. The dynamic α was significantly greater than the static α.

Masseter-to-facial nerve transfer is a reliable technique for smile reanimation. However, it has only a limited effect on the improvement of symmetry at rest. Assessing the preoperative symmetry of the oral commissure at rest can be used to predict postoperative outcomes, and patients with severe droop of the oral commissure (symmetry scale grade III or IV) should receive static suspension.