Neuro-behavioral pattern of sleep bruxism in wakefulness

Abstract

Introduction: Sleep Bruxism (SB) is a non-functional rhythmic movement of the mandible with multifactorial aetiology and complex diagnose. It has been the subject of various studies over the past decades and it is considered a result of actions of the Central Nervous System modulated by Autonomous Nervous System. In this work, we test the hypothesis that SB subjects present a typical and defined neurobehavioral pattern that can be distinct from that of non-bruxers subjects and can be measured during wakefulness. Methods: Fifteen sleep bruxers (experimental-group EG) and fifteen non-bruxers (control-group CG) took part in the experiments. To verify the presence and severity of SB, clinical examinations, anamneses and questionnaires, including Visual Analogic Scale -faces (VAS-f) and State-Trait Anxiety Inventory (STAI) were applied. To legitimate the diagnoses of SB, a disposable instrument (Bitestrip  ) to assess the masseter activity during sleep was employed. All subjects were submitted to a set of experiments for measuring various visual evoked responses during the presentation of visual stimuli (pleasant, unpleasant and neutral images). Events in Visual Evoked Potential (VEP) were used to compare the neural responses of both CG and EG. Results: VAS-f showed EG with higher perception of stress than CG (trait: p=0.05), and lower quality of life for (state: p=0.007). STAI I and II showed significant differences of anxiety between CG and EG (p=0.013 and p=0.004, respectively), being EG the highest. The EG Bitestrip scores confirmed that 100% of subjects were sleep bruxers. Significant differences were found between EG and CG for events associated with emotional (pleasant and unpleasant) images in the first 250 ms after stimulation. In general, EG subjects showed higher amplitude and shorter latency of VEP events. Conclusion: It is possible to distinguish between SB and non-bruxers subjects during wakefulness, based on differences in amplitude and latency of cortical event related potentials elicited by visual stimulation. SB subjects show greater amplitudes in specific events in frontal areas when non-pleasant images are shown. Latencies tend to be anticipated in SB compared to CG subjects.

Association between sleep bruxism and anxiety symptoms in adults: A systematic review

“…Although some authors suggested that probable SB could be associated with anxiety symptoms, conflicting results were observed. Overall, a positive association between definite SB and generic anxiety levels were observed in one study, between probable SB and generic anxiety levels in another one . and with dental anxiety in one study .…”

“…One study with definite SB and other with probable SB reported that STAI‐1 and STAI‐2 scores were significantly higher among SB participants comparing to controls. Only one study evaluated dental anxiety using the MDAS questionnaire and although no significant differences were observed regarding MDAS total scores, MDAS very anxious or extremely anxious scores were significantly higher among SB individuals …”

“…Eight analytical cross‐sectional studies published between 2004 and 2018 were included, of which one was conducted in Brazil, two in Italy, one in Mexico, two in Spain and two in Turkey . Overall, a total of 1252 participants were enrolled and, with regard to sample size of included studies, the largest study population encompassed 526 individuals, while 30 participants were enrolled in the smallest sample . Moreover, only two of the included studies performed a priori calculations to estimate sample size; it is unclear if studies with no sample size estimation could be biased due to insufficient number of participants to detect differences between groups …”

“…Regarding the question “Was the exposure measured in a valid and reliable way?”, only one study stated that researchers were previously calibrated to assess SB . In addition, four studies did not clearly report any methods to deal with confounders and were, therefore, considered at high risk of bias regarding this domain . Further information about the risk of bias assessment can be found in Figure .…”

“…Azevedo et al investigated 30 individuals, of which 15 were assessed with SB by using an instrumental approach (portable diagnostic device). In addition, generic symptoms of anxiety were assessed through the STAI‐1 and STAI‐2 scales.…”