Development of an intraoral device for facial muscle retraining and its clinical application.

The aim of this work was to develop a facial neuromuscular retraining technique for cases of facial palsy, involving an easy-to use intraoral device that allows correcting abnormal neuromuscular patterns and improving esthetics. Facial palsy is a motor alteration of multiple origin that results in facial asymmetry. Treatment remains controversial to date and includes, surgical anastomosis and decompressive and plastic surgery, corticosteroids therapy, injection of botulinum toxin, and administration of other medicinal drugs. Physical therapy involving electrical stimulation and feedback are also used to retrain facial muscles. A removable thermopolymerized acrylic intraoral device with wrought wire clasps was developed and constructed. The device was used on a patient with facial palsy who was instructed to wear it 4 times a day during 20 minutes and perform exercises in front of the mirror, trying to coordinate the action of the device with the smile movement on the unaffected side of the face. Digital photographs of the patient were taken during smile movement and at rest with and without the device, and movements of the oral commissures were compared using specific software. Results showed anatomic and nonanatomic indices of facial motion for the lower part of the face with the device to be 1.77 and 0 respectively. The device improved facial symmetry during rest by opposing traction forces of the contralateral muscles, resulting in a better position of the filtrum during rest, and allowed the patient to exercise smile movements at home.