[An electromyographic observation of the extensional labiobuccal flange lower complete denture].

The electromyogram of the buccinator and the myoid muscles in 26 lower full denture patients with severe atrophic alveoli were measured separately in three groups: group one, the conventional dentures: group two, the extension flange dentures in preliminary stage after the denture insertion and group three, the extensional flange denture in forward stage. The main results showed that (1) the functional force, except on mouth opening, exerted by the buccinator muscles increased significantly in group two and three. (2) the functional force exerted by the mylohyoid muscles on mouth opening decreased significantly in group two and increased in group three which was similar to group one. There were no significant difference between these three groups on swallowing. (3) the functional force except on mouth opening, exerted by the buccinator and mylohyoid muscles between these three groups was no significant difference. These observations indicated that there was no significant interference in the physiological activities of the buccinator and the mylohyoid muscles with the extensional flange dentures. In addition, the extensional buccal flange may enhance the denture retention.