Statement of problem:The improvement of the oral function of implant retained mandibular overdentures may depend on the degree of retention and stability of the denture and thus on the type of attachment.Purpose of the study: The aim of the study was to evaluate of the effect of two different attachment designs with different resiliency of implant retained mandibular overdentures on the masticatory function.Methods: Twelve completely edentulous patients were selected for the study each patient received two interforaminal implants in the canine areas of the mandible using standardized two-stage surgical technique. Implants were left unloaded for three months. Six of the patients received implant overdenture with ball and socket attachment first then the same denture was modified to receive positioner attachment. The other six patients received the implant overdenture with positioner first then the same denture was modified to receive ball and socket. Muscle activity and maximum muscle activity of both temporalis and masseter muscles were recorded during chewing cake, peanut and during clenching with using the electromyography.Results: Muscle activity and maximum muscle activity showed higher results with the positioner attachment in both masseter and temporalis muscles although the difference was not statistically significant. Masseter muscle showed higher results in both types of the attachments.
Conclusion:The positioner attachment might be selected over Ball & Socket attachment when designing a two implant retained mandibular overdentures since it is more superior from the masticatory function point of view.