Masticatory muscle activity assessment and reliability of a portable electromyographic instrument

Abstract

Statement of Problem. Masticatory muscle hyperactivity is thought to produce muscle pain and tension headaches and can cause excessive wear or breakage of restorative dental materials used in the treatment of prosthodontic patients. The quantification and identification of this type of activity is an important consideration in the preoperative diagnosis and treatment planning phase of prosthodontic care. Purpose. This study investigated the quantification process in complete denture/overdenture patients with natural mandibular tooth abutments and explored the reliability of instrumentation used to assess this parafunctional activity. Material and Methods. The nocturnal EMG activity in asymptomatic complete denture/overdenture subjects was assessed with and without prostheses worn during sleep. Because of the large variance within and between subjects, the investigators evaluated the reliability of the 3 instruments used to test nocturnal EMG activity in the sample. Results. Electromyographic activity data of denture/overdenture subjects revealed no differences between prostheses worn versus not worn during sleep but demonstrated a very large variance factor. Further investigation of the instrumentation demonstrated a consistent in vitro as well as in vivo reliability in controlled laboratory studies. Conclusion. The portable EMG instrumentation used in this study revealed a large, uncontrollable variance factor within and between subjects that greatly complicated the diagnosis of parafunctional activity in prosthodontic patients. (J Prosthet Dent 2001;85:252-60.)