2017 Volume 42 Issue 1 Pages 12-21
To clarify the relationship between para-functional activity of the masticatory muscles and damage status of the implant superstructure, muscle activity in normal daily life was examined using a portable electromyograph (EMG).
Ten patients with repeat fractures of the superstructures caused by unconscious bruxism were enrolled. Those were classified into two groups depending on the damage: catastrophic failure (CF)and control (CO). The portable EMG recording device employed in this study has a one-channel EMG recording system and is composed of a remote control, a main unit, and an electrode unit. The portable EMG recording device was worn on the masseter muscle during the morning period (about 24 hours), and was able to detect bruxism without interfering in daily life. Obtained EMG data was transferred to the computer and analyzed using proprietary software. Based on our previous studies, thresholds were arranged to set the standard.
Bruxism-like events were observed in all subjects, and events beyond the threshold were also detected. The muscle mass activity per observed hour (parafunction) during awaking was higher than that during sleeping in all subjects. CF was significantly higher than CO. In contrast, no significant difference of functional activity was detected between those groups (P<0.05: MannWhitney U-test).
Patients with CF recorded greater muscle mass activity than the patients with CO. Those results suggested that the damage in the implant supported prostheses could be correlated to muscular mass activity.
