Effect of osseointegrated implants on the coordination of masticatory muscles: A pilot study

Statement of problem. Thr neuromuscular network of masticatory function is, in part, coordinated with afferent information provided by the periodontal ligament (PDL). Osseointegrated implant-supported pros theses lack this PD L-derived proprioceptive feedback mechanism. Purpose, This pilot study was designed to address the hypothesis that impla nt patients acquire different patterns of functional coordination. Patients with implant-supported prostheses were characterized in regard to masticat ory muscle tenderness and fatigue as well as changes in the coordinated act ivities of masticatory muscles during chewing and maximal occluding force. Results were compared with those of patients with natural teeth and interpr eted to assess the functional outcome of implant therapy. Material and methods. Fifty-seven volunteers (25 partially edentulous patie nts restored with implant supported fixed prostheses; 32 control patients) were evaluated. A comprehensive set of clinical examinations was performed, including occlusal analysis and examination of masticatory muscle and TMJ. EMG recordings of 5 volunteers from each group were further evaluated. EMG activities of the masseter and anterior anterior were recorded during habi tual chewing; and voluntary maximal occluding force. Results, There were essentially no differences in the clinical evaluations between volunteers in the implant and control groups and no significant alt erations in the masticatory muscle coordination for habitual chewing. Durin g the maximal occluding force measurement, EMG recordings revealed a unique masticatory muscle coordination pattern in the implant group with a tenden cy to activate the working and nonworking side muscles simultaneously Conclusion. Patients with implant-supported prostheses appeared to be well adapted to perform habitual masticatory functions. However, during a nonhab itual function such as maximal occluding force, our pilot data revealed a l ess coordinated masticatory muscle activity in the implant patients.