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Aims: To explore whether traumatic brain injury (TBI) patients have a higher prevalence of sleep bruxism (SB) and a higher level of orofacial muscle activity than healthy controls and whether orofacial muscle activity in the context of mild TBI (mTBI) increases the risk for headache disability. Methods: Sleep laboratory recordings of 24 mTBI patients (15 males, 9 females; mean age ± standard deviation [SD]: 38 ± 11 years) and 20 healthy controls (8 males, 12 females; 31 ± 9 years) were analyzed. The primary variables included degree of headache disability, rhythmic masticatory muscle activity (RMMA) index (as a biomarker of SB), and masseter and mentalis muscle activity during quiet sleep periods. Results: A significantly higher prevalence of moderate to severe headache disability was observed in mTBI patients than in controls (50% vs 5%; P = .001). Although 50% and 25% of mTBI patients had a respective RMMA index of ≥ 2 episodes/hour and ≥ 4 episodes/hour, they did not present more evidence of SB than controls. No between-group differences were found in the amplitude of RMMA or muscle tone. Logistic regression analyses suggested that while mTBI is a strong predictor of moderate to severe headache disability, RMMA frequency is a modest but significant mediator of moderate to severe headache disability in both groups (odds ratios = 21 and 2, respectively). Conclusion: Clinicians caring for mTBI patients with poorly controlled headaches should screen for SB, as it may contribute to their condition. Keywords: headache, polysomnography, rhythmic masticatory muscle activity, sleep bruxism, traumatic brain injury

Aims: To investigate the hypothesis that the presence of transient morning masticatory muscle pain in young, healthy sleep bruxers (SBr) is associated with sex-related differences in sleep electroencephalographic (EEG) activity. Methods: Data on morning masticatory muscle pain and sleep variables were obtained from visual analog scales and a second night of polysomnographic recordings. Nineteen normal control (CTRL) subjects were age- and sex-matched to 62 tooth-grinding SBr. Differences in sleep macrostructure (stage distribution and duration, number of sleep-stage shifts), number of rhythmic masticatory muscle activity (RMMA) events/ hour, and EEG activity were analyzed blind to subject status. The influence of pain and gender in SBr and CTRL subjects was assessed with the Fisher's exact test, Mann-Whitney U test, two-sample t test, and analysis of variance (ANOVA). Results: Low-intensity morning transient orofacial pain was reported by 71% of SBr, with no sex difference. RMMA event frequency was higher in SB than CTRL subjects (4.5/hour vs 1.3/hour; P .001). SBr had fewer sleep-stage shifts, irrespective of sex or pain status. Female SBr had significantly lower theta and alpha EEG activity compared to female CTRL subjects (P = .03), irrespective of pain. Conclusion: Female SBr had lower theta and alpha EEG activity irrespective of transient morning pain. Keywords: EEG power spectral analysis, pain, sex, sleep bruxism, theta wave activity

Aims: To evaluate the influence of an oral appliance on morning headache and orofacial pain in subjects without reported sleep-disordered breathing (SDB). Methods: Twelve subjects aged 27.6 ± 2.1 (mean ± SE) years and suffering from frequent morning headache participated in this study. Each subject was individually fitted with a mandibular advancement appliance (MAA). The first two sleep laboratory polygraphic recording (SLPR) nights were for habituation (N1) and baseline (N2). Subjects then slept five nights without the MAA (period 1: P1), followed by eight nights with the MAA in neutral position (P2), ending with SLPR night 3 (N3). Subjects then slept five nights without the MAA (P3), followed by eight nights with the MAA in 50% advanced position (P4), ending with SLPR night 4 (N4). Finally, subjects slept 5 nights without the MAA (P5). Morning headache and orofacial pain intensity were assessed each morning with a 100-mm visual analog scale. Repeated measures ANOVAs and Friedman tests were used to evaluate treatment effects. Results: Compared to the baseline period (P1), the use of an MAA in both neutral and advanced position was associated with a >= 70% reduction in morning headache and >= 42% reduction in orofacial pain intensity (P = .001). During the washout periods (P3 and P5), morning headache and orofacial pain intensity returned to close to baseline levels. Compared to N2, both MAA positions significantly reduced (P .05) rhythmic masticatory muscle activity (RMMA). Conclusion: Short-term use of an MAA is associated with a significant reduction in morning headache and orofacial pain intensity. Part of this reduction may be linked to the concomitant reduction in RMMA. Keywords: mandibular advancement appliance, morning headache, oral appliance, orofacial pain, rhythmic masticatory muscle activity

The phenomenon of sleep bruxism (SB) has been recognized and described for centuries, including literary references to the gnashing of teeth. Early etiologic explanations were generally focused on mechanistic factors, but later, attention was focused on psychologic issues such as stress and anxiety; by the end of the 20th century, most opinions combined these two ideas. However, recently, the study of the SB phenomena has occurred primarily in sleep laboratories in which patients could be observed and monitored over several nights. Various other physiologic systems were also studied in sleep laboratories, including brain activity, muscle activity, cardiac function, and breathing. As a result of these studies, most authorities now consider SB to be a primarily sleep-related movement disorder, and specific diagnostic criteria have been established for the formal diagnosis of that condition. All of these changes in the understanding of the SB phenomena have led to a corresponding change in thinking about how oral appliances (OAs) might be used in the management of SB. Originally, they were thought to be a temporary measure that could help dentists analyze improper dental relationships. Unfortunately, this often led to dental procedures to "improve" these relationships, including equilibrations, orthodontics, bite opening, or even major restorative dentistry. However, it is now understood that the proper role for OAs is to protect the teeth and hopefully to diminish muscle activity during sleep. This paper reviews these evolutionary changes in the understanding of SB and how this affects concepts of designing and using OAs.

Purpose: This study investigated whether the presence of tooth wear in young adults can help to discriminate patients with sleep bruxism (SB) from control subjects. Materials and Methods: The tooth wear clinical scores and frequency of sleep masseter electromyographic activity of 130 subjects (26.6 ± 0.5 years) were compared in this case-control study. Tooth wear scores (collected during clinical examination) for the incisors, canines, and molars were pooled or analyzed separately for statistics. Sleep bruxers (SBrs) were divided into two subgroups according to moderate to high (M-H-SBr; n = 59) and low (L-SBr; n = 48) frequency of masseter muscle contractions. Control subjects (n = 23) had no history of tooth grinding. The sensitivity and specificity of tooth wear versus SB diagnosis, as well as positive and negative predictive values (PPV and NPV), were calculated. One-way analysis of variance and the Mann-Whitey U test were used to compare groups. Results: Both SBr subgroups showed significantly higher tooth wear scores than the control group for both pooled and separated scores (P .001). No difference was observed between M-H-SBr and L-SBr frequency groups (P = .14). The pooled sum of tooth wear scores discriminates SBrs from controls (sensitivity = 94%, specificity = 87%). The tooth wear PPV for SB detection was modest (26% to 71%) but the NPV to exclude controls was high (94% to 99%). Conclusions: Although the presence of tooth wear discriminates SBrs with a current history of tooth grinding from nonbruxers in young adults, its diagnostic value is modest. Moreover, tooth wear does not help to discriminate the severity of SB. Caution is therefore mandatory for clinicians using tooth wear as an outcome for SB diagnosis.

Purpose: The objective of this experimental study was to assess the efficacy and safety of a reinforced adjustable mandibular advancement appliance (MAA) on sleep bruxism (SB) activity compared to baseline and to a mandibular occlusal splint (MOS) in order to offer an alternative to patients with both tooth grinding and respiratory disorders during sleep. Materials and Methods: Twelve subjects (mean age: 26.0 ± 1.5 years) with frequent SB participated in a short-term (three blocks of 2 weeks each) randomized crossover controlled study. Both brain and muscle activities were quantified based on polygraphic and audio/video recordings made over 5 nights in a sleep laboratory. After habituation and baseline nights, 3 more nights were spent with an MAA in either a slight (25%) or pronounced (75%) mandibular protrusion position or with an MOS (control). Analysis of variance and Friedman and Wilcoxon signedrank tests were used for statistical analysis. Results: The mean number of SB episodes per hour was reduced by 39% and 47% from baseline with the MAA at a protrusion of 25% and 75%, respectively (P .04). No difference between the two MAA positions was noted. The MOS slightly reduced the number of SB episodes per hour without reaching statistical significance (34%, P = .07). None of the SB subjects experienced any MAA breakage. Conclusion: Short-term use of an MAA is associated with a significant reduction in SB motor activity without any appliance breakage. A reinforced MAA design may be an alternative for patients with concomitant tooth grinding and snoring or apnea during sleep.

This tribute article to Professor Barry J. Sessle summarizes the 6 presentations delivered at the July 1, 2008 symposium at the University of Toronto. The symposium honored 3 "giants" in orofacial neuroscience, Professors B.J. Sessle, J.P. Lund, and A.G. Hannam. The 6 presentations paying tribute to Sessle spanned the period from the early phase of his career up to some of his most recent studies with colleagues in Asia, Europe, and Australia as well as Canada. The studies have included those providing an improved understanding of the cortical control of sensory inputs in pain perception (presented by R. Dubner) and in the control of mastication and swallowing, as well as brainstem mechanisms of orofacial pain (K. Iwata, G. Murray). His current activities in his laboratory and in Denmark are also highlighted (L. Avivi-Arber, P. Svensson). The potential transfer of basic research discoveries toward drug development in pain control that stem from some of his research is also described (B. Cairns). The final section of the paper includes a commentary from Professor Sessle. Keywords: experimental pain, hypertonic saline, jaw muscles, jaw movement, motor cortex, sensorimotor

Purpose: The objective of this experimental study was to compare the effect on sleep bruxism and tooth-grinding activity of a double-arch temporary custom-fit mandibular advancement device (MAD) and a single maxillary occlusal splint (MOS). Materials and Methods: Thirteen intense and frequent bruxors participated in this short-term randomized crossover controlled study. All polygraphic recordings and analyses were made in a sleep laboratory. The MOS was used as the active control condition and the MAD was used as the experimental treatment condition. Designed to temporarily manage snoring and sleep apnea, the MAD was used in 3 different configurations: (1) without the retention pin between the arches (full freedom of movement), (2) with the retention pin in a slightly advanced position ( 40%), and (3) with the retention pin in a more advanced position (> 75%) of the lower arch. Sleep variables, bruxism-related motor activity, and subjective reports (pain, comfort, oral salivation, and quality of sleep) were analyzed with analysis of variance and the Friedman test. Results: A significant reduction in the number of sleep bruxism episodes per hour (decrease of 42%, P .001) was observed with the MOS. Compared to the MOS, active MADs (with advancement) also revealed a significant reduction in sleep bruxism motor activity. However, 8 of 13 patients reported pain (localized on mandibular gums and/or anterior teeth) with active MADs. Conclusions: Short-term use of a temporary custom-fit MAD is associated with a remarkable reduction in sleep bruxism motor activity. To a smaller extent, the MOS also reduces sleep bruxism. However, the exact mechanism supporting this reduction remains to be explained. Hypotheses are oriented toward the following: dimension and configuration of the appliance, presence of pain, reduced freedom of movement, or change in the upper airway patency.