Background: Electromyographic (EMG) activities of single implant-retained mandibular overdentures (MODs) has been dubious. Midline fracture of the denture is the most common complication related to Single implant-retained MODs. Thermoplastic polymethylmethacrylate (PMMA) acrylic resin achieves even distribution of forces and helps in absorption of impact forces which occurs during functional and parafunctional activities.
Aim of the study: This clinical study aimed to investigate whether thermoplastic PMMA can improve the EMG activity and decrease the incidence of denture fracture in single implant- retained MODs. Materials and Methods: A randomized controlled trial was designed, where 28 completely edentulous patients (15 male, 13 female) were enrolled and randomly divided into two equal groups. Group I (control group) received single implant- retained MOD fabricated from conventional PMMA and group II received a single implant- retained MOD fabricated from thermoplastic PMMA acrylic resin. Patients' muscle activity was evaluated at baseline and at 3, 6 and 12 months using EMG. The survival rate of MOD was evaluated by recording the incidence of mid-line fractures. Results: There was a significant improvement in the EMG activity of the masseter and temporalis muscle of the thermoplastic PMMA group in all the follow-up periods. There was a non-statistically significant difference in the MOD survival between groups. However, the decrease in fracture incidence was clinically significant in the thermoplastic PMMA acrylic MOD group.
Conclusion: Within the limitation of this study, it was concluded that the fabrication of single implant-retained MODs from thermoplastic PMMA acrylic resins improves masticatory muscle activity and overdenture survival.