In this study, the hypothesis was examined that a better retention and stability of a mandibular denture improve oral function. Eighteen edentulous subjects received 2 permucosal implants, a new denture, and successively 3 types of mesostructures (magnets, ball, bar-clip). Maximum bite force and electrical activity of the masseter and temporalis muscles were measured at various moments. The maximum bite force of an implant-retained overdenture nearly doubled, when compared with the new denture without mesostructure, independent of the type of mesostructure. With an implant-retained overdenture maximum bite force was two-thirds of the value obtained for dentate subjects. No large differences in muscle activity were found among the 3 types of mesostructures. Temporalis activity was significant lower than masseter activity when subjects clenched with their old conventional denture and with the new denture without mesostructure. There was no difference in activity of muscles when subjects clenched with an implant-retained overdenture.