Nocturnal masseter electromyographic activity of complete denture wearers

Objective: Collection of normative data on activity patterns of the masseter during sleep in elderly denture wearers by portable electromyography (EMG) recorders. Background: Complete denture wearers might suffer from orofacial pain caused by myoarthropathies of the masticatory system. Indeed, denture instability may precipitate parafunctional habits and consequently muscle soreness and/or temporomandibular pain. Materials and methods: We collected normative masseter EMG data during sleep in 15 complete denture wearers (five women, 10 men, 56-88 years) by portable recorders in their natural environment. Activity periods (AP) were signal portions including subthreshold intervals <= 5 s. Signal amplitude was expressed in per cent of maximum voluntary contraction (%MVC). For this reason, maximum bite force was assessed. Twenty age-matched dentate controls were also recorded for the maximum bite force. Results: We found 157.2 +/- 86.5 AP per night, i.e. 24.0 +/- 12.2 AP/h. Mean amplitude was 15.1 +/- 4.3%MVC. AP lasted 6.8 +/- 4.1 s, and their time integral was 126.3 +/- 112.5%MVC center dot s. Maximum bite force was 116.8 +/- 69.6 N in the edentulous, significantly lower than in controls (344.8 +/- 150.4 N). Conclusions: Healthy complete denture wearers showed intermittent periods of nocturnal masseter activity of very low intensity and short duration.