Changes in Smile Symmetry and Perceived Emotions in Patients with Facial Synkinesis after Depressor Anguli Oris Myectomy: A Long-Term Follow-up Study

<b>Introduction:</b> Depressor anguli oris (DAO) myectomy improves smile symmetry and emotions conveyed with a smile in synkinesis patients. However, no long-term follow-up studies have been reported. <b>Objective:</b> To evaluate long-term changes in smile symmetry and emotions conveyed with smile in synkinesis patients after DAO myectomy. <b>Methods:</b> Synkinesis patients who underwent DAO myectomy between August 2021 and December 2023 with at least 12-months of follow-up were retrospectively reviewed. Patient-reported, clinician-graded, and objective outcomes were compared. <b>Results:</b> Fifty patients (84% female, median age 45.00 years old [16-79], median follow-up 21.57 months [12.10-37.10]) were included. Patients reported improved quality of life and smile symmetry on the facial clinimetric survey (<i>p</i> < 0.001). Blinded electronic facial paralysis assessments revealed improved oral commissure excursion with smile (<i>p</i> = 0.01). Emotrics+ analysis revealed improved upper lip (<i>p</i> = 0.014), oral commissure (<i>p</i> < 0.001), and dental display (<i>p</i> < 0.001) symmetry with smile. FaceReader analysis demonstrated patients conveyed 13% more happiness with smile after surgery (<i>p</i> < 0.001) and fewer negative emotions (<i>p</i> = 0.05). While further improvements were seen after 3 months, these changes were not statistically significant. <b>Conclusions:</b> DAO myectomy likely results in long-term improvements in smile symmetry and happiness conveyed with smile in synkinesis patients. Postoperative outcomes at 3 months appear to be predictive of long-term results.