Specific Diurnal EMG Activity Pattern Observed in Occlusal Collapse Patients: Relationship between Diurnal Bruxism and Tooth Loss Progression

Abstract

AimThe role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep.Materials and MethodsSix progressive bite collapse patients (PBC group), six age- and gender-matched control subjects (MC group), and six young control subjects (YC group) were enrolled. Electromyograms (EMG) of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching.ResultsHighly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01). ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss.ConclusionExtensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep.Clinical Relevance: Scientific rationale for studyAlthough mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking.Principal findingsThis study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse.Practical implicationsThe incidence of diurnal phasic contractions could be used for the prognostic evaluation of stomatognathic system stability.

Oral Parafunction - Aetiology, Implications and Relation to Orthodontic Treatment

“…The latter affect at least 75% of the adult population. These data confirm that more teeth are lost due to these diseases than to the effects of caries [12,58,59].…”

Does pain in the masseter and anterior temporal muscles influence maximal bite force?

“…Therefore, it would be necessary to use polysomnography (gold standard) for confirmation of sleep bruxism (Lavigne et al, 2000). For awake bruxism, it would be necessary to use a method for evaluation of muscle contractions during the day (Kawakami, Kumazaki, Manda, Oki, & Minagi, 2014). Another limitation of this study is the absence of a control group.…”

Bruxism Unconscious Oral Habit in Everyday Life

“…When a patient has daily bruxism, he usually denies that he is pressing and clenching his teeth because they’re unaware of the habit [45]. Generally, in these patients sleep is relatively good.…”