The effect of flexible acrylic resin on masticatory muscle activity in implant-supported mandibular overdentures: a controlled clinical trial

Background: It is not yet clear from the current literature to what extent masticatory muscle activity is affected by the use of flexible acrylic resin in the construction of implant-supported mandibular overdentures. Objective: To compare masticatory muscle activity between patients who were provided with implant-supported mandibular overdentures constructed from flexible acrylic resin and those who were provided with implant- supported mandibular overdentures constructed from heat-cured conventional acrylic resin. Methods: In this clinical trial, 12 completely edentulous patients were selected and randomly allocated into two equal treatment groups. Each patient in Group 1 received two implants to support a mandibular overdenture made of conventional acrylic resin. In Group 2, the patients received two implants to support mandibular overdentures constructed from “Versacryl” flexible acrylic resin. The maxillary edentulous arch for patients in both groups was restored by conventional complete dentures. For all patients, masseter and temporalis muscle activity was evaluated using surface electromyography (sEMG). Results: The results showed a significant decrease in masticatory muscle activity among patients with implant- supported mandibular overdentures constructed from flexible acrylic resin. Conclusion: The use of “Versacryl” flexible acrylic resin in the construction of implant-supported mandibular overdentures resulted in decreased masticatory muscle activit