Evaluation of sleep bruxism by three-dimensional analysis of the deformation of acrylic resin occlusal appliances.

PURPOSE

To establish the relationship between rhythmic masticatory muscle activity (RMMA) of the masseter muscle during sleep bruxism (SB) and occlusal wear and distortion in the stabilization occlusal appliance (OcA) used for its treatment.

METHODS

Seventeen adults with SB wore OcAs composed of polymethyl methacrylate for 28 days. Weekly recordings included electromyography (EMG) of the masseter muscle using a wearable EMG device, evaluation of SB variables, and 3D scanning of the OcA using a 3D dental model scanner. The awake bite force at the time of recruitment was measured using a film-based bite force measurement system. The 3D data collected weekly before and after wearing the OcA were superimposed, and the weekly deformations in the coronal-apical directions were calculated. The masseter muscle activity per hour (RMMA index) and OcA deformation were compared weekly. Finally, we investigated the relationship between the frequency and intensity of the masseter muscle activity patterns and OcA deformation.

RESULTS

No significant differences were observed in weekly RMMA index; however, all OcA deformations were significant. Apical deformation, including occlusal wear, was positively correlated with awake bite force. Coronal deformation reflecting distortion was positively correlated with the number of sustained tonic masseter muscle activities and maximum masseter muscle activities.

CONCLUSIONS

OcA deformation measured using this system reflects the frequency and intensity of the RMMA and masseter muscle activity in patients with SB, suggesting its potential as a novel clinical diagnostic tool for SB.