MASSETER MUSCLE FATIGUE BEFORE AND AFTER REHABILITATION WITH IMPLANT-SUPPORTED PROSTHESES

To establish whether different implant-supported prosthetic reconstruc tions influence jaw muscle resistance to clenching efforts, sustained submaximal (50%) clenching was performed in two groups of patients who were edentulous in one or both jaws. One group consisted of patients who were rehabilitated by means of an overdenture on two to four impla nts connected by a bar; the other group consisted of patients who were rehabilitated with an implant-supported fixed prosthesis on four to s even implants in either the maxilla or the mandible. Results indicated that after rehabilitation with implant-supported fixed reconstruction s, the myoelectric output level increased over time, which was paralle l to a higher bite force level. For the other group, such a time-depen dent change in electromyographic amplitude did not occur. On the other hand, power spectrum analysis revealed a significant downward shift o f the mean power frequency during sustained clenching after rehabilita tion with implant-supported overdentures but not with implant-supporte d fixed prostheses. The absence of a spectral shift in the latter grou p probably expressed a fear of biting too hard and fracturing the pros thesis.