Functional evaluation of implant supported prostheses

Purpose: Surface electromyography is currently considered a useful tool for dentistry allowing the validation of conventional morphological evaluations with an accurate and objective quantification of the functional activity. An evaluation of full mouth resin prostheses on implants was performed including both a morphological evaluation of occlusion and a measurement of the actual impact of morphology on stomatognathic function. Methodology: The measurement was performed using masticatory muscle electromyographic recordings with ad-hoc software algorithms. In the present study, five patients with full mouth resin prostheses on implants have been evaluated at the beginning of their prosthetic reconstructions and after one year using surface electromyography. To verify the static neuromuscular equilibrium of occlusion, functional evaluation of the left and right masseter and temporalis anterior muscles was performed in all patients, and a set of indices was computed: the Percentage Overlapping Coefficient – POC (an index of the symmetric distribution of the muscular activity determined by the occlusion), the Torque Coefficient - TC (an index of the possible presence of a mandibular torque) and the antero-posterior coefficient (an index of the possible relative position of the occlusal center of gravity). Results: One year after surgery during the maximum voluntary clench, all patients had symmetric standardized potentials (POC values between 80% and 100%, and TC values larger than 90%). Conclusions: Surface electromyography indices were well super imposable to the values found in healthy subjects with natural and normal occlusion, thus indicating that, at short time follow up, a functionally stable occlusion could protect from resin prosthodontic fractures.