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Objective: To consider the possible role of the vagus nerve (VN) in the pathophysiology of sleep bruxism (SB) and introduce a multimodal protocol of transcutaneous auricular stimulation of the VN in the treatment of SB patients., Methods: Ten patients with SB underwent four sessions of electric transcutaneous auricular vagus nerve stimulation (ta-VNS) in specific auricular areas. The patients were advised to manually stimulate the same areas between sessions. Masticatory muscle activity and sleep parameters were measured by a polysomnography (PSG) before and after the treatment. Heart rate variability (HRV) parameters were measured during each stimulation., Results: PSG analysis revealed a statistically significant reduction in tonic SB index and tonic contraction time. HRV parameters showed a statistically significant increase in mean values of the vagal tone after each session of stimulation. No side effect was reported., Conclusion: The stimulation of the VN might have a role in the treatment of SB.

Diagnosis of bruxism is challenging because not all contractions of the masticatory muscles can be classified as bruxism. Conventional methods for sleep bruxism detection vary in effectiveness. Some provide objective data through EMG, ECG, or EEG; others, such as dental implants, are less accessible for daily practice. These methods have targeted the masseter as the key muscle for bruxism detection. However, it is important to consider that the temporalis muscle is also active during bruxism among masticatory muscles. Moreover, studies have predominantly examined sleep bruxism in the supine position, but other anatomical positions are also associated with sleep. In this research, we have collected EMG data to detect the maximum voluntary contraction of the temporalis and masseter muscles in three primary anatomical positions associated with sleep, i.e., supine and left and right lateral recumbent positions. A total of 10 time domain features were extracted, and six machine learning classifiers were compared, with random forest outperforming others. The models achieved better accuracies in the detection of sleep bruxism with the temporalis muscle. An accuracy of 93.33% was specifically found for the left lateral recumbent position among the specified anatomical positions. These results indicate a promising direction of machine learning in clinical applications, facilitating enhanced diagnosis and management of sleep bruxism.

Study Objectives: To determine the prevalence and risk factors of sleep bruxism (SB) in adults with primary snoring (PS)., Methods: This study included 292 adults with PS (140 males, 152 females; mean age ± standard deviation = 42.8 ± 12.2 years; mean body mass index ± standard deviation = 26.7 ± 4.7 kg/m 2 ) without previous treatment for snoring. SB was diagnosed based on the frequency of the biomarker of SB: rhythmic masticatory muscle activity (SB when rhythmic masticatory muscle activity ≥ 2 episodes/h). Logistic regression was performed, with SB as the dependent variable and with age, sex, body mass index, and sleep- and respiratory-related polysomnographic parameters as the independent variables to identify the risk factors for SB., Results: The prevalence of SB was 44.6% in adults with PS. Younger age (odds ratio = 0.965 [0.944, 0.987]) and shorter total sleep time (odds ratio = 0.760 [0.609, 0.948]) significantly increased the risk of SB ( P < .05)., Conclusions: SB is highly prevalent in adults with PS. Younger age and shorter sleep time are significant risk factors for SB in adults with PS., Clinical Trial Registration: Registry: onderzoekmetmensen.nl; Name: A Large Sample Polysomnographic Study on Sleep Bruxism; URL: https://trialsearch.who.int/Trial2.aspx?TrialID=NL-OMON19947; Identifier: NL8516., Citation: Li D, Lobbezoo F, Hilgevoord AAJ, de Vries N, Aarab G. Prevalence and risk factors of sleep bruxism in adults with primary snoring: a large-scale polysomnographic study. J Clin Sleep Med . 2024;20(8):1331-1337., (© 2024 American Academy of Sleep Medicine.)

Background: The etiology of sleep bruxism in obstructive sleep apnea (OSA) patients is not yet fully clarified. This prospective clinical study aimed to investigate the connection between probable sleep bruxism, electromyographic muscle tone, and respiratory sleep patterns recorded during polysomnography., Methods: 106 patients with OSA (74 males, 31 females, mean age: 56.1 ± 11.4 years) were divided into two groups (sleep bruxism: SB; no sleep bruxism: NSB). Probable SB were based on the AASM criteria: self-report of clenching/grinding, orofacial symptoms upon awakening, abnormal tooth wear and hypertrophy of the masseter muscle. Both groups underwent clinical examination for painful muscle symptoms aligned with Temporomandibular Disorders Diagnostic Criteria (DC/TMD), such as myalgia, myofascial pain, and headache attributed to temporomandibular disorder. Additionally, non-complaint positive muscle palpation and orofacial-related limitations (Jaw Functional Limited Scale-20: JFLS-20) were assessed. A one-night polysomnography with electromyographic masseter muscle tone (EMG) measurement was performed. Descriptive data, inter-group comparisons and multivariate logistic regression were calculated., Results: OSA patients had a 37.1% prevalence of SB. EMG muscle tone (N1-N3, REM; P = 0.001) and the number of hypopneas (P = 0.042) were significantly higher in the sleep bruxism group. While measures like apnea-hypopnea-index (AHI), respiratory-disturbance-index (RDI), apnea index (AI), hypopnea-index (HI), number of arousals, and heart rate (1/min) were elevated in sleep bruxers, the differences were not statistically significant. There was no difference in sleep efficiency (SE; P = 0.403). Non-complaint masseter muscle palpation (61.5%; P = 0.015) and myalgia (41%; P = 0.010) were significant higher in SB patients. Multivariate logistic regression showed a significant contribution of EMG muscle tone and JFLS-20 to bruxism risk., Conclusion: Increased EMG muscle tone and orofacial limitations can predict sleep bruxism in OSA patients. Besides, SB patients suffer more from sleep disorder breathing. Thus, sleep bruxism seems to be not only an oral health related problem in obstructive apnea. Consequently, interdisciplinary interventions are crucial for effectively treating these patients., Trial Registration: The study was approved by the Ethics Committee of Philipps-University Marburg (reg. no. 13/22-2022) and registered at the "German Clinical Trial Register, DRKS" (DRKS0002959)., (© 2024. The Author(s).)

The purpose of this study is to evaluate the effects of botulinum toxin type A (BoNT-A) for managing sleep bruxism (SB) in a randomized, placebo-controlled trial. Thirty SB subjects were randomly assigned into two groups evenly. The placebo group received saline injections into each masseter muscle, and the treatment group received BoNT-A injections into each masseter muscle. Audio-video-polysomnographic recordings in the sleep laboratory were made before, at four weeks after, and at 12 weeks after injection. Sleep and SB parameters were scored according to the diagnostic and coding manual of American Academy of Sleep Medicine. The change of sleep and SB parameters were investigated using repeated measures analysis of variance (RM-ANOVA). Twenty-three subjects completed the study (placebo group 10, treatment group 13). None of the SB episode variables showed a significant time and group interaction ( p > 0.05) except for electromyography (EMG) variables. The peak amplitude of EMG bursts during SB showed a significant time and group interaction ( p = 0.001). The injection decreased the peak amplitude of EMG bursts during SB only in the treatment group for 12 weeks ( p < 0.0001). A single BoNT-A injection cannot reduce the genesis of SB. However, it can be an effective management option for SB by reducing the intensity of the masseter muscle.

Background: Sleep bruxism is a masticatory muscle activity characterized as rhythmic (phasic) or nonrhythmic (tonic). In children and adolescents, etiological factors, such as breathing pattern and sleep quality, have recently been addressed in studies investigating sleep bruxism. New therapies for adults, such as botulinum toxin, have been investigated, but such techniques are not applicable for individuals in the growth and development phase., Methods: The participants will be 76 children, which will be randomly allocated to a control group, that is group 1, absence of bruxism; group 2, children with bruxism treated with infrared light-emitting diode (LED); and group 3, bruxism treated with occlusal splint. All participants will be submitted to a clinical evaluation to evaluate muscle activity and salivary biomarkers, before and after treatments. Muscle activity will be verified by electromyography of muscles mastication, masseter and temporal, and salivary biomarkers observed will be cortisol and dopamine levels., Discussion: Photobiomodulation therapy has piqued the interest of researchers, as this noninvasive method has demonstrated positive results in problems related to muscle tissues. This document describes the protocol for a proposed study to evaluate morphological and psychosocial aspects in children and adolescents with awake bruxism and their responses to photobiomodulation therapy with infrared LED. CLINICAL TRIALS:.

Objective: To evaluate the utility of vacuum-pressed, BruxChecker ® sheets for the diagnosis of sleep bruxism., Methods: Twenty subjects participated in this study. Tooth contact during sleep was recorded using a 0.1 mm-thick polyvinyl chloride sheet called BruxChecker ® . The area of the BruxChecker ® in which the red dye was removed was measured. In addition, the EMG activity of the masseter muscle during sleep was recorded. The numbers of bruxism bursts and episodes were counted, and their correlations with the peeled area of the red dye on the BruxChecker ® were evaluated., Results: The number of bruxism bursts and episodes/hr significantly correlated with the peeled area at all cut-off values. The peeled area significantly correlated with the number of phasic type bruxism episodes but not with tonic or mixed type bruxism episodes., Discussion: Since the BruxChecker ® peeled area reflected phasic type sleep bruxism, the sheets may be useful in sleep bruxism screening.

Study Objectives: To evaluate the prevalence of probable sleep bruxism (SB) and its association with sleep features, orthodontic fixed appliance wearing, and extraoral and intraoral clinical signs and symptoms in a population of adolescents., Methods: Two hundred thirty-nine 12-year-old adolescents enrolled in private and public schools in Brumadinho, southeast Brazil, and their parents were invited to participate. They answered a questionnaire containing information regarding adolescents' sleep features and history of SB. Extraoral and intraoral examination was performed to identify some clinical signs (ie, absence of lip competence, presence of mouth breathing, clicks in the temporomandibular joint [TMJ], tooth wear) and symptoms (ie, pain in the masseter muscle upon palpation), and ongoing orthodontic treatment with fixed appliances. Parental report and clinical examination were used to determine probable SB. Descriptive statistics and logistic regression were performed to identify association of probable SB with independent variables., Results: Of 239 adolescents initially selected, 231 (96.6%) participated in the study. Prevalence of probable SB was 16.9%. Adolescents who snored during sleep (odds ratio [OR] = 3.14; 95% confidence interval [CI] = 1.47-6.70), adolescents who did not have clicks in the TMJ (OR = 3.37; 95% CI = 1.11-10.15), and those who wore orthodontic appliances (OR = 2.72; 95% CI = 1.04-7.14) were more likely to be in the group with probable SB., Conclusions: Snoring, absence of clicks in the TMJ, and fixed appliance wearing were associated with probable SB among adolescents. This study adds to the ongoing research on SB in adolescents and its associated factors., Commentary: A commentary on this article appears in this issue on page 1281., (© 2018 American Academy of Sleep Medicine.)

Study Objectives: To examine the presence of a first-night effect (FNE) and the level of internight variability in sleep bruxism (SB) activity when a self-applicable electrode set is used in home polysomnography (PSG) in a sample of subjects with possible SB., Methods: Fourteen females and two males aged 38.3 ± 9.1 years (mean ± standard deviation) with self-reported SB underwent home-PSG on three consecutive nights. The subjects applied PSG sensors themselves, including self-applicable electrode sets used to record sleep and masseter muscle activity. Repeated-measures analysis of variance was used to compare SB and sleep variables between the nights., Results: Surprisingly, there were statistically significant elevations in the rhythmic masticatory muscle activity (RMMA) episode index ( P = .009), burst index ( P = .016), and bruxism time index ( P = .049) throughout the course of 3 nights. More bruxers were diagnosed on the second (6 bruxers, ≥ 2 episodes/h) and third night (7 bruxers) compared to the first night (2 bruxers). Most subjects (14/16) had their highest RMMA index on the second or third night. The mean coefficient of variation for RMMA episode index was 50.7%. No statistically significant differences were detected in other sleep variables., Conclusions: The results indicate that a FNE may be present in SB activity, possibly lasting several nights in some subjects. Furthermore, FNE appears to be combined with high internight variability of SB activity without indications of internight changes in sleep macrostructure. To confirm the level of ongoing SB activity, several nights of PSG may be required, especially in subjects with low first-night SB activity., Commentary: A commentary on this article appears in this issue on page 1281., (© 2018 American Academy of Sleep Medicine.)

Objective: Bruxism-induced mechanical load causes various dental problems, and its treatment is challenging. The present study analyzed upper and lower tooth contacts to determine actual occlusal contact during sleep bruxism., Methods: Tooth contact patterns were analyzed in 49 patients attending dental clinics, using a Bruxchecker®, cephalograms, and condylographs., Results: Approximately 80% of individuals demonstrated contact from the anterior teeth to the molar region (ICPM); about 96% had mediotrusive grinding and contact. The tooth contact area increased with the flatness of the anterior occlusal plane. The ratio of the contact area of the anterior teeth to the overall tooth contact area increased with overbite. Bilateral ICPM and mediotrusive contact patterns were associated with a high frequency of temporomandibular disorder symptoms, clicking, and/or pain., Discussion: The tooth contact area, anterior occlusal plane, and overbite are closely related, suggesting that tooth contact with the anterior teeth should be controlled with occlusal therapy.

Background: One of the widespread problems of oral health is bruxism and is defined as a parafunctional habit with involuntary grinding and gnashing of the teeth occurring during sleep. However, bruxism is connected to anxiety and stress, but the published literature on bruxism among prison inmates is scanty. Objective: The objective of the study was to determine the prevalence of active sleep bruxism and its impact on oral health-related quality of life (OHRQoL) among inmates in Central Penal Institution, Mysore., Materials and Methods: The study was cross sectional and conducted among eligible male inmates at Central Penal Institution, Mysore. The information on active sleep bruxism and OHRQoL was collected using a predesigned structured questionnaire by means of personal interview by a trained investigator. The active sleep bruxism was assessed using the criteria of American Academy of Sleep Medicine and OHRQoL through modified oral health impact profile (OHIP-14). The data analysis was done using descriptive statistics, Chi-square test, t-test, analysis of variance, and linear regression model., Results: A total of 212 male inmates aged between 18 and 80 years were considered for the study. The prevalence of active sleep bruxism among the study population was 31.6%. The mean OHIP-14 score was significantly higher (P < 0.001) among the inmates having active sleep bruxism (38.52 ± 12.8) suggesting a high oral health impact as compared to inmates without this disorder (31.67 ± 12)., Conclusion: The prevalence of active sleep bruxism was higher among the inmates of penal institution as compared to the general population. The active sleep bruxism had a negative impact on OHRQoL., Competing Interests: There are no conflicts of interest

The possible effects on sleep bruxism (SB) of clear aligners in orthodontics are unknown. This study was conducted to analyze the effects of clear aligners on SB. Sixty subjects needing orthodontic treatment and affected by SB (33 m, 27 f, 20±;5 years) were enrolled in the study and randomly assigned to one of the following three groups: 20 were given clear aligners (CAT) (12 m, 8 f, 19±5 years), 20 occlusal splint (MOS) (9 m, 11 f, 22±5 years) and 20 a placebo splint (PMS) (12 m, 8 f, 24±3 years). All groups were followed for 6 consecutive months and monitored for SB with a portable electromyographic-electrocardiographic (EMG-ECG) device (Bruxoff®, OT Bioelettronica, Torino, Italy). MOS subjects reduced masseter contractions after 6 months of treatment (t3) (MD=-29.11, std. error 11.74, p=0.017) but increased phasic contractions related to SB after 3 months of treatment (t2) (MD=4.73, std. error 2.36, p=0.048) and tonic contractions related to SB during all the six months of treatment (t1, t2, t3) when compared to PMS. CAT subjects increased phasic contractions related to SB during the first (t1) (MD=3.94, std. error 2.27, p=0.04) and the third month (t2) of treatment (MD=4.62, std. error 2.36, p=0.046) when compared to PMS. No significant differences were found for SB index at any time for all the three groups. Although MOS and CAT affected EMG signals during sleep time differently, they did not influence the overall SB index.

Objectives: To confirm the relationship between sleep bruxism (SB) and autonomic nervous (AN) activities to elucidate SB physiology., Methods: Subjects included 11 healthy males (mean age, 24.7 ± 2.3 years). These data were recorded in the sleep laboratory using a system composed of a two-axis accelerometer, an infrared camera, electroencephalography, electromyography, and electrocardiography. Time lapse analysis confirmed correlations between AN activity and SB events during sleep in subjects. Relationships between SB strength and length and AN activity were evaluated., Results: Sympathetic nerve (SN) and parasympathetic nerve (PSN) activities occurred significantly in 93.3% of cases (p < 0.01), with similar predictable patterns during SB. Furthermore, SB length and SN activity in seven of the subjects (four subjects, p < 0.05; three subjects p < 0.01), and PSN and SB muscle activities (% maximum voluntary contraction) in five subjects (four subjects, p < 0.05; one subject, p < 0.01) were significantly correlated., Discussion: The authors believe that SB is closely related to SN as well as PSN activities and may control the AN system.

The aim of the present study was to evaluate factors associated with sleep bruxism in five-year-old preschool children. A preschool-based cross-sectional study was conducted with 761 pairs of children and their parents/caregivers. Sleep bruxism was diagnosed using a questionnaire administered to the parents/caregivers, who also answered questionnaires addressing sociodemographic data and parent's/caregiver's sense of coherence. Clinical oral evaluations of the children to determine dental caries, traumatic dental injuries, malocclusion and tooth wear were performed by two researchers who had undergone a training exercise (interexaminer Kappa: 0.70 to 0.91; intraexaminer Kappa: 0.81 to 1.00). Descriptive analysis and logistic regression for complex samples were carried out (α = 5%). The prevalence of sleep bruxism among the preschool children was 26.9%. The multivariate analysis revealed that bruxism was associated with poor sleep quality (OR = 2.93; 95 CI: 1.52-5.65) and tooth wear (OR = 2.34; 95%CI: 1.39-3.96). In the present study, sleep bruxism among preschool children was associated with tooth wear and poor sleep quality of the child. In contrast, psychosocial aspects (sense of coherence) were not associated with sleep bruxism.

Objective: To evaluate whether there is a relationship between possible sleep bruxism (PSB), temporomandibular disorders (TMD), unilateral chewing (UC), and occlusal factors in university students recruited from Cumhuriyet University in Turkey., Methods: For this cross-sectional survey, 519 (223 males, mean age 21.57 ± 2.3 years, 296 females, mean age 21.02 ± 2 years) university students who admitted to the Department of Oral and Maxillofacial Radiology of the Faculty of Dentistry, Cumhuriyet University for dental care between 2012 and 2014 were selected randomly. Students were asked to complete a questionnaire form including questions about TMD, PSB and UC. Presence and direction of malocclusion were recorded during clinical examination. Chi-square test was used for statistical analysis., Results: It was found that 96.6% of the students with PSB had TMD (p < 0.05). The prevalence of severe TMD was high among students with PSB. There was a significant association between UC, PSB and TMD (p < 0.05). No statistically significant association was found between occlusal factors and PSB and TMD (p > 0.05)., Conclusion: Sleep bruxism, which heavily depends on self-report, is significantly associated with TMD. Unilateral chewing seems to be a common factor for development of SB and TMD. However, further studies are needed to corroborate this finding. Additionally, this study supports the hypothesis that occlusal factors are not related to self-reported sleep bruxism.

Sleep bruxism (SB) and obstructive sleep apnoea syndrome (OSAS) share common pathophysiologic pathways. We aimed to study the presence and relationship of SB in a OSAS population. Patients referred with OSAS suspicion and concomitant SB complains were evaluated using a specific questionnaire, orofacial evaluation and cardio-respiratory polygraphy that could also monitor audio and EMG of the masseter muscles. From 11 patients studied 9 had OSAS. 55.6% were male, mean age was 46.3±11.3 years, and apnea hypopnea index of 11.1±5.7/h. Through specific questionnaire 55.6% had SB criteria. Orofacial examination (only feasible in 3) confirmed tooth wear in all. 77.8% had polygraphic SB criteria (SB index>2/h). Mean SB index was 5.12±3.6/h, phasic events predominated (72.7%). Concerning tooth grinding episodes, we found a mean of 10.7±9.2 per night. All OSAS patients except two (77.8%) had more than two audible tooth-grinding episodes. These two patients were the ones with the lowest SB index (1.0 and 1.4 per hour). Only in one patient could we not detect tooth grinding episodes. There was a statistically significant positive correlation between tooth grinding episodes and SB index and phasic event index (R=0.755, p=0.019 and R=0.737, p=0.023 respectively, Pearson correlation). Mean apnoea to bruxism index was 0.4/h, meaning that only a minority of SB events were not secondary to OSAS. We could not find any significant correlation between AHI and bruxism index or phasic bruxism index (R=-0.632 and R=-0.611, p>0.05, Pearson correlation). This pilot study shows that SB is a very common phenomenon in a group of mild OSAS patients, probably being secondary to it in the majority of cases. The new portable device used may add diagnostic accuracy and help to tailor therapy in this setting., (Copyright © 2016 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L.U. All rights reserved.)

Introduction: A growing body of evidence suggests that bruxism exists in two separate manifestations. However, little is known about the association between specific manifestations of bruxism and temporomandibular disorder (TMD) pain., Aim: The aim of our study was to analyze the association between TMD pain and specific diagnoses of bruxism (sleep, awake, and mixed diagnosis of sleep and awake bruxism)., Material and Methods: 508 adult patients (296 women and 212 men), aged between 18 and 64 years (mean age 34±12 years), attending to a clinic for general dental treatment. Patients were asked to fill an anonymous questionnaire, consisting of three questions, verifying the presence of TMD pain and two forms of bruxism. All questions were based on the Polish version of the Research Diagnostic Criteria for Temporomandibular Disorders patient history questionnaire. Cross tabulation was done, and χ 2 was used as a test of significance to find the association between the variables., Results: Awake bruxism was associated with TMD pain only in men (χ 2 =7.746, p<0.05) while mixed diagnosis of bruxism was associated with TMD pain in both women (χ 2 =10.486, p<0.05) and men (χ 2 =4.314, p<0.05). There was no statistically significant association between sleep bruxism and TMD pain. Gender-related differences in the presence of all bruxism diagnoses were also statistically insignificant., Conclusions: Interaction between sleep and awake bruxism may increase the risk for TMD pain. We suggest considering concomitance as a confounder, when studying sleep or awake bruxism., (Copyright © 2016 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Objectives: Details on grinding patterns and types of contact during sleep bruxism in association with migraine headache have not yet been elucidated. This study compared the characteristics of sleep bruxism between patients with migraine and controls., Methods: The study included 80 female patients who had been diagnosed with migraine and 52 women with no history of migraine. Grinding patterns were measured using the BruxChecker® (Scheu Dental, Iserlohn, Germany)., Results: There was a significant difference between the two groups in the distribution of grinding patterns at the laterotrusive side (p < 0.001). When the anterior teeth and premolar and molar regions in the two groups were compared, the proportion of the grinding area at all sites was significantly larger in the migraine group than in the control group (p < 0.001)., Discussion: The BruxChecker® showed that there was substantial grinding over a large area among migraine patients, particularly in the molar region.

Objectives: This study aimed to analyze the impact of sleep bruxism (SB) on electromyography (EMG) activity and the thickness of the masseter and temporal and maximal molar bite force., Method: Ninety individuals, aged between 18 and 45 years, were selected and divided into two groups: Group I (case group, 45 individuals with SB) and Group II (control group, 45 individuals without SB). A diagnosis of SB was made from polysomnography., Results: The data obtained from EMG and the muscle thickness and the maximal molar bite force were tabulated (SPSS 21.0), normalized, and subjected to statistical analysis (p ≤ 0.05). Comparisons between the groups showed significant differences regarding the habitual chewing of hard food for the left temporalis muscle (p = 0.04) and the chewing of soft food for the right masseter muscle (p = 0.04), but no significant differences for the measurements of muscle thickness and maximal molar bite force., Discussion: The present data suggest that SB negatively altered the masticatory muscles' functions. Based on the results of this research, it can be concluded that individuals with SB showed decreased EMG activity in the masticatory muscles.

Objectives: The aim of this study was to elucidate characteristics of rhythmic masticatory muscle activity (RMMA) during sleep by comparing masseteric EMG (electromyogram) activities of RMMA with gum chewing., Method: The parts of five or more consecutive phasic bursts in RMMA of 23 bruxers were analyzed. Wilcoxon signed-rank test for matched pairs and Spearman's correlation coefficient by the rank test were used for statistical analysis., Results: Root mean square value of RMMA phasic burst was smaller than that during gum chewing, but correlates to that of gum chewing. The cycle of RMMA was longer than that of gum chewing due to the longer burst duration of RMMA, and variation in the cycles of RMMA was wider., Discussion: These findings suggest that the longer but smaller EMG burst in comparison with gum chewing is one of the characteristics of RMMA. The relation between size of RMMA phasic bursts and gum chewing is also suggested.

The purpose of this study was to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on patients with sleep bruxism (SB). Twelve patients with SB were included in an open, single-intervention pilot study. rTMS at 1 Hz and an intensity of 80% of the active motor threshold was applied to the 'hot spot' of the masseter muscle representation at the primary motor cortex bilaterally for 20 min per side each day for 5 consecutive days. The jaw-closing muscle electromyographic (EMG) activity during sleep was recorded with a portable EMG recorder at baseline, during rTMS treatment and at follow-up for 5 days. In addition, patients scored their jaw-closing muscle soreness on a 0-10 numerical rating scale (NRS). Data were analysed with analysis of variance. The intensity of the EMG activity was suppressed during and after rTMS compared to the baseline (P = 0.04; P = 0.02, respectively). The NRS score of soreness decreased significantly during and after rTMS compared with baseline (P < 0.01). These findings indicated a significant inhibition of jaw-closing muscle activity during sleep along with a decrease of muscle soreness. This pilot study raises the possibility of therapeutic benefits from rTMS in patients with bruxism and calls for further and more controlled studies.

Objectives: This study estimated the maximum tongue pressure (MTP) against teeth in bruxers, and verified the effect of a stabilization splint., Method: Forty subjects (mean age: 26.57 years) were assigned to two groups (n520): bruxers and nonbruxers. Sleep bruxism was diagnosed by self-report, presence of tooth wear and tongue indentation, and by using a BiteStrip2 device. Maximum tongue pressure was measured by intraoral appliances containing pressure sensors. After baseline evaluation, bruxers received a stabilization splint and non-bruxers received a palatal splint, both for nocturnal use. Maximum tongue pressure was reassessed after 30 and 60 days. Data were submitted to repeated-measures ANOVA and Tukey test (Pv0.05)., Results: Bruxers showed an increased MTP against teeth (Pv0.05). Splint therapy decreased MTP for bruxers and non-bruxers., Discussion: Bruxers present tongue indentations or ulcerations; however, there is no evidence on their MTP. Further research should focus on therapies to avoid tongue ulcerations in bruxers.

Objective: To evaluate the diagnostic capability of signs and symptoms of sleep bruxism (SB) as per the American Academy of Sleep Medicine (AASM) criteria and a diagnostic grading system proposed by international experts for assessing SB., Methods: The study was conducted in three phases (interview, physical examination, and sleep studies). Subjects were asked about self-reported tooth grinding sounds occurring during sleep, muscle fatigue, temporal headaches, jaw muscle pain, and jaw locking. A visual examination was conducted to check for presence of abnormal tooth wear. A full-night polysomnography (PSG) was performed. After three phases, the subjects were divided into two groups matched by age and gender: Case Group, 45 SB subjects, and Control Group, 45 non-SB subjects. Diagnostic accuracy measurements were calculated for each sign or symptom individually and for the two diagnostic criteria analyzed., Results: Muscle fatigue, temporal headaches, and AASM criteria were associated with highest sensitivity (78%, 67%, 58%, respectively) and also with highest diagnostic odds ratio (OR = 9.63, 9.25, 6.33, respectively). Jaw locking, muscle pain, and the criterion of "probable SB" were associated with the worst sensitivity (16%, 18%, 22%, respectively)., Conclusions: Presence of muscle fatigue and temporal headaches can be considered good tools to screen SB patients. None of the diagnostic criteria evaluated was able to accurately identify patients with SB. AASM criteria had the strongest diagnostic capabilities and--although they do not attain diagnostic values high enough to replace the current gold standard (PSG)--should be used as a screening tool to identify SB., (© 2015 American Academy of Sleep Medicine.)

Objectives: This cross-sectional study aimed to evaluate the influence of Primary Headache (PH) on efficacy of a Temporomandibular Disorders (TMD) conservative therapy and its association with the presence of self-reported parafunctional habits., Sample and Methods: Sample was composed of 400 medical records, divided into four groups: I) Muscular TMD (n = 64); II) Muscular TMD+PH (n = 48); III) Muscular TMD+Articular TMD (n = 173); IV) Muscular TMD+Articular TMD+PH (n = 115). All groups had undergone a TMD therapy for three months with a stabilization appliance and counseling for habits and behavioral changes, with no specific headache management. Current pain intensity and existence or not of self-reported bruxism were assessed. Repeated measures ANOVA and Chi-Square test followed by Odds were used for statistical analysis, with a significance level of 5%., Results: results of this study showed that: (1) A conservative therapy with stabilization appliance and counseling for habits and behavioral changes was effective in the TMD pain relief; (2) Groups with an additional diagnosis of PH had worsened the pain improvement significantly; and (3) no association between the presence of self-reported bruxism and PH was found., Conclusions: this study could elucidate the important effect that headache may have on the TMD management.

Objectives: The purpose of the present study was to compare craniofacial morphology and bite force of bruxist patients with signs and symptoms of temporomandibular disorders., Method: Fourteen subjects with sleep bruxism and 14 healthy subjects participated. The signs and symptoms of the temporomandibular disorders were identified according to the Craniomandibular Index (CMI). Maximum bite force was measured using strain-gage transducers. Lateral cephalometric films were taken, and linear and angular measurements were performed., Results: Bite force between bruxist and non-bruxist females was not significant, whereas males with bruxism revealed higher bite forces. None of the linear and angular measurements differed significantly between bruxist and non-bruxist males. However, higher mandibular corpus length and anterior cranial base length, and lower gonial angle were observed in bruxist females compared to non-bruxist females. Negative correlation between bite force and CMI values was found in both genders., Discussion: Bruxist females had higher CMI values than bruxist males, which could lead to relatively lower bite forces.

Background: Bruxism is the involuntary grinding of teeth that occurs during sleep or wake time. The prevalence of bruxism in children and adolescents is high when compared to the adult population., Clinical Presentation: This article presents a case report of sleep bruxism in a 6-year-old child. The interesting finding here was its association with nocturnal enuresis (NE)/bedwetting., Conclusion/clinical Relevance: NE could be a predisposing factor for sleep bruxism in children, as it causes emotional stress and has a negative impact on a child's self esteem. Psychological support and techniques for overcoming NE, like a scheduled waking program at night helps children with these problems by alleviating the associated stress. In addition, NE and bruxism are often associated with other sleep disorders, such as obstructive sleep apnea syndrome, and hence, child bruxers require careful medical evaluation to rule out such potential interactions.

Study Objectives: Sleep bruxism (SB) is reported to vary in frequency over time. The aim of this study was to assess the first night effect on SB., Methods: A retrospective polysomnographic (PSG) analysis was performed of data from a sample of SB patients (12 females, 4 males; age range: 17-39 years) recorded in a sleep laboratory over 2 consecutive nights. Sleep parameters and jaw muscle activity variables (i.e., rhythmic masticatory muscle activity [RMMA]) for SB were quantified and compared between the 2 nights. Subjects were classified into groups according to severity of RMMA frequency, such as low frequency (2-4 episodes/h and/or < 25 bursts/h) and moderate-high frequency (≥ 4 episodes/h and ≥ 25 bursts/h)., Results: Overall, no first night effects were found for most sleep variables. However, total sleep time, sleep efficiency, and stage transitions showed significant time and group interactions (repeated measures ANOVAs, p ≤ 0.05). The RMMA episode index did not differ between the 2 nights, whereas the second night showed significantly higher burst index, bruxism time index, and mean burst duration (repeated measure ANOVAs, p ≤ 0.05). Five patients of 8 in the low frequency group were classified into the moderate-high frequency group on the second night, whereas only one patient in the moderate-high frequency group moved to the low frequency group., Conclusions: The results showed no overall first night effect on severity of RMMA frequency in young and healthy patients with SB. In clinical practice, one-night sleep recording may be sufficient for moderate-high frequency SB patients. However, low RMMA frequency in the first night could be confirmed by a second night based on the patient's medical and dental history.

Background: Tasks can be instruments of stress and may affect the health of children. Sleep bruxism is a multifactorial sleep-related movement disorder that affects children and adults. The aim of the present study was to analyze the association between children's tasks, personality traits and sleep bruxism., Methods and Findings: A cross-sectional, population-based study of 652 randomly selected Brazilian schoolchildren (52% of whom were female), aged from 7 to 10 years was conducted in the city of Belo Horizonte, Brazil. A questionnaire based on criteria proposed by the American Academy of Sleep Medicine (AASM) was completed by parents. In addition, the Neuroticism and Responsibility sub-scales of the Big Five Questionnaire for Children (BFQ-C) were administered to the children. Psychological tests were administered and evaluated by psychologists. The Social Vulnerability Index from the city council database was used to determine the social classification of the families. Chi-square and Poisson regression statistical tests were used with a 95% confidence interval. The majority of families were classified as having low social vulnerability (61.3%), whereas, 38.7% were classified as having high social vulnerability. Regarding extracurricular activities, the majority of girls performed household work (56.4%) and some artistic activity (51.3%) while sporting activities were most common among boys (61%). The results of the Poisson regression model indicated that sleep bruxism was most prevalent in children who scored highly in the Neuroticism sub-scale, and who frequently performed household tasks., Conclusion: Children whose personality domain has a high level of Neuroticism and who perform household chores imposed by the family are more vulnerable to sleep bruxism.

Aim: This study evaluates the relationship between occlusal interferences and premature contacts and bruxism by determining the relationship between unassisted and assisted nonworking interferences., Materials and Methods: In this study, 60 subjects (14 males and 46 females) that consisted of 30 bruxers (7 males, 23 females) and 30 nonbruxers (7 males, 23 females) were selected after completion of a questionnaire based on the exclusion criteria. Occlusal interferences in the centric relation and eccentric movements in the two groups were evaluated and recorded. Data were analyzed by SPSS software (version 16) using the Chi-square and paired t-tests., Results: The results showed a statistically significant relationship between bruxism and nonworking interferences (p < 0.05). There was no statistically significant relationship in the centric relation and other eccentric movements (p > 0.05). The number of assisted nonworking occlusal contacts was more than unassisted nonworking occlusal contacts., Conclusion: According to the results of this study, there is a relationship between certain types of occlusal interferences (nonworking interferences) and bruxism. Hence, it would be useful to examine occlusal contacts in bruxing patients to eliminate probable causative or contributing occlusal factors. Both assisted and unassisted nonworking occlusal contacts should be evaluated., Clinical Implication: Bruxism is an oral habit that consists of involuntary rhythmic or spasmodic nonfunctional gnashing, grinding or teeth clenching, other than chewing movements by the mandible. Bruxism may lead to occlusal trauma, tooth wear, fracture of the teeth and fillings, and hypertrophy of the masticatory muscles. Treatment of bruxism needs a correct diagnosis. Therefore, it is useful to determine the relationship between occlusal interferences and bruxism in order to prevent its development by adjusting for these interferences.

The purpose of the study was to clarify the effect of a stabilization splint (SS) on the distribution of occlusal force around the dental arch during voluntary submaximal tooth clenching. Ten healthy volunteers participated in this study. For each subject, the maxillary SS was made of heat-cured hard acrylic resin with approximately one mm thickness at the molar regions. The subjects were asked to perform static clenching at either 40% or 80% maximum voluntary contraction (MVC) levels, with and without the SS in place, using visual feedback. The occlusal contact area and occlusal force were analyzed. When the SS was inserted, the mean tooth contact area and occlusal force significantly decreased at both 40% and 80% MVC levels (p < 0.01). The location of the occlusal balancing point changed towards the anterior after insertion of the SS. The results suggest that the SS has potential to reduce individual tooth-loading forces by evenly distributing the forces generated during sleep bruxism.

This study was conducted to verify the results of a preceding retrospective pilot study by means of a prospective controlled investigation including a larger sample size. Therefore, the aim of this clinical investigation was to analyze the relationship between sleep bruxism and several functional and occlusal parameters. The null hypothesis of this study was that there would be no differences among sleep bruxism subjects and non-sleep bruxism controls regarding several functional and occlusal parameters. Fifty-eight sleep bruxism subjects and 31 controls participated in this study. The diagnosis sleep bruxism was based on clinical criteria of the American Academy of Sleep Medicine. Sixteen functional and occlusal parameters were recorded clinically or from dental study casts. Similar to the recently published retrospective pilot study, with a mean slide of 0.77 mm (s.d., 0.69 mm) in the sleep bruxism group and a mean slide of 0.4 mm (s.d., 0.57 mm) in the control group, the evaluation of the mean comparison between the two groups demonstrated a larger slide from centric occlusion to maximum intercuspation in sleep bruxism subjects (Mann-Whitney U-test; P=0.008). However, following Bonferroni adjustment, none of the 16 occlusal and functional variables differed significantly between the sleep bruxism subjects and the non-sleep bruxism controls. The present study shows that the occlusal and functional parameters evaluated do not differ between sleep bruxism subjects and non-sleep bruxism subjects. However, as the literature reveals a possible association between bruxism and certain subgroups of temporomandibular disorders, it appears advisable to incorporate the individual adaptive capacity of the stomatognathic system into future investigations.

Sleep bruxism, an intensified manifestation of rhythmic masticatory muscle activity, characterized by tooth grinding or clenching during sleep, lacks a definitive physiological purpose. This paper posits that physiologically, sleep bruxism is an autonomic self-regulatory response to nighttime occurrences of tachycardia stemming from the brain experiencing microarousals during sleep. Sleep bruxism by triggering the trigeminal cardiac reflex leads to bradycardia. Rhythmic masticatory muscle activity-sleep bruxism, thereby, serves to slow the heart rate when brain microarousals cause tachycardia.

Conditions that affect sleep can impact overall health. More than 70 million Americans suffer from problems with sleep. The purpose of this article is to provide the basic science of sleep physiology and how it relates to disorders that are pertinent to dentistry. Concepts are presented that explain airway dynamics and how the jaw and tongue influence airway obstruction. Additionally, explanation is given on an association between temporomandibularj aw dysfunction and bruxism during sleep.

The biomechanical load during strong bruxism activity reportedly causes many dental/oral problems. However, it is unknown whether the magnitude of muscle activity during sleep is controllable. In this study, the relationship between the magnitude of muscle activity during sleep and types of tooth contacts was examined, including anterior and posterior guidance, in order to clarify how occlusion factors contribute to sleep bruxism (SB). An EMG-2-axis accelerometer system was used for monitoring patterns and activities of SB. Bruxchecker was used to evaluate tooth contacts during SB, and a condylograph was used to measure posterior guidance (sagittal condylar inclination). Results show that grinding rather than clenching or tapping was observed in the high SB group, and there was Incisor-Canine-Premolar-Molar (ICPM) tooth contact during SB grinding movement. The canine occlusal guidance (COG) was flatter in the low SB group than in the moderate SB group. Relative canine occlusal guidance (rCOG), which is the difference between the sagittal condylar inclination (SCI) and COG, was larger in the low SB group than that in the high SB group. These findings suggest that the grinding pattern must be controlled to prevent strong bruxism, and that the muscle activity during bruxism can be reduced by controlling the tooth contact pattern during SB grinding.

The aim of this study was to evaluate the association between various functional and occlusal parameters and sleep bruxism. Thirty-nine (39) sleep bruxism patients and 30 controls participated in this investigation. The assessment of sleep bruxism was performed using the Bruxcore Bruxism-Monitoring Device (BBMD) combined with a new computer-based analyzing method. Sixteen functional and/or occlusal parameters were recorded. With a mean slide of 0.95 mm in the sleep bruxism group and a mean slide of 0.42 mm in the control group (Mann Whitney U test; p<0.003), results solely demonstrated a significant group difference regarding the length of a slide from centric occlusion to maximum intercuspation. The results suggest that the slightly pronounced slide could be of clinical importance in the development of increased wear facets in patients with current sleep bruxism activity. Following further evaluation including polysomnographic recordings, the BBMD combined with this new analyzing technique seems to be a clinically feasible instrument that allows the practitioner to quantify abrasion over a short period.

Exaggerated jaw motor activities during sleep are associated with muscle symptoms in the jaw-closing rather than the jaw-opening muscles. The intrinsic activity of antagonistic jaw muscles during sleep remains unknown. This study aims to assess the balance of muscle activity between masseter (MA) and digastric (DG) muscles during sleep in guinea pigs. Electroencephalogram (EEG), electroocculogram, and electromyograms (EMGs) of dorsal neck, MA, and DG muscles were recorded with video during sleep-wake cycles. These variables were quantified for each 10-s epoch. The magnitude of muscle activity during sleep in relation to mean EMG activity of total wakefulness was up to three times higher for MA muscle than for DG muscle for nonrapid eye movement (NREM) and rapid-eye-movement (REM) sleep. Although the activity level of the two jaw muscles fluctuated during sleep, the ratio of activity level for each epoch was not proportional. Epochs with a high activity level for each muscle were associated with a decrease in deltaEEG power and/or an increase in heart rate in NREM sleep. However, this association with heart rate and activity levels was not observed in REM sleep. These results suggest that in guinea pigs, the magnitude of muscle activity for antagonistic jaw muscles is heterogeneously modulated during sleep, characterized by a high activity level in the jaw-closing muscle. Fluctuations in the activity are influenced by transient arousal levels in NREM sleep but, in REM sleep, the distinct controls may contribute to the fluctuation. The above intrinsic characteristics could underlie the exaggeration of jaw motor activities during sleep (e.g., sleep bruxism).

Objective: To evaluate the influence of gender and bruxism on the ability to discriminate minimum interdental threshold., Material and Methods: One hundred and fifteen individuals, representing both genders, bruxers and non-bruxers, with a mean age of 23.64 years, were selected for this study. For group allocation, every individual was subjected to a specific physical examination to detect bruxism (performed by three different examiners). Evaluation of the ability to discriminate minimum interdental threshold was performed using industrialized 0.010 mm-, 0.024 mm-, 0.030 mm-, 0.050 mm-, 0.080 mm- and 0.094 mm-thick aluminum foils that were placed between upper and lower premolars. Data were analyzed statistically by multiple linear regression analysis at 5% significance level., Results: Neither gender nor bruxism influenced the ability to discriminate minimum interdental threshold (p>0.05)., Conclusions: Gender and the presence of bruxism do not play a role in the minimum interdental threshold.

Background: Sleep bruxism has been described as a combination of different orofacial motor activities that include grinding, clenching and tapping, although accurate distribution of the activities still remains to be clarified., Methods: We developed a new system for analyzing sleep bruxism to examine the muscle activities and mandibular movement patterns during sleep bruxism. The system consisted of a 2-axis accelerometer, electroencephalography and electromyography. Nineteen healthy volunteers were recruited and screened to evaluate sleep bruxism in the sleep laboratory., Results: The new system could easily distinguish the different patterns of bruxism movement of the mandible and the body movement. Results showed that grinding (59.5%) was most common, followed by clenching (35.6%) based on relative activity to maximum voluntary contraction (%MVC), whereas tapping was only (4.9%)., Conclusion: It was concluded that the tapping, clenching, and grinding movement of the mandible could be effectively differentiated by the new system and sleep bruxism was predominantly perceived as clenching and grinding, which varied between individuals.

The purpose of this study was to investigate the effects of sleep bruxism on periodontal sensation and tooth displacement in the molar region. Twenty-eight (28) subjects lacking objective or subjective abnormalities in stomatognathic function were divided into two groups representing bruxers (n=14) and controls (n=14). Sleep bruxism was confirmed based on the nocturnal electromyography activity of the masseter muscle. Periodontal sensation was assessed based on interocclusal tactile threshold (ITT), which refers to the minimal thickness that can be detected between the occlusal surfaces of the teeth. ITT was measured in the first molar region. Displacement of teeth during clenching was measured using a two-dimensional tooth displacement transducer. Statistical analysis of the differences in ITT and tooth displacement between the bruxers and controls was performed by Mann Whitney U-test (p < 0.05). Mean ITT for bruxers was significantly lower than that for controls (p < 0.01). The mean displacement of both the maxillary and mandibular first molar for the bruxers was significantly larger than that for the controls (p < 0.05). The results of this study suggest that sleep bruxism affects both periodontal sensation and tooth displacement.

Introduction: Sleep bruxism as nocturnal parafunction, also known as tooth grinding, is the most common parasomnia (sleep disorder). Most tooth grinding occurs during rapid eye movement - REM sleep. Sleep bruxism is an oral habit characterized by rhythmic activity of the masticatory muscles (m. masseter) that causes forced contact between dental surfaces during sleep. Sleep bruxism has been associated with craniomandibular disorders including temporomandibular joint discomfort, pulpalgia, premature loss of teeth due to excessive attrition and mobility, headache, muscle ache, sleep interruption of an individual and problems with removable and fixed denture. Basically, two groups of etiological factors can be distinguished, viz., peripheral (occlusal) factors and central (pathophysiological and psychological) factors. The role of occlusion (occlusal discrepancies) as the causative factor is not enough mentioned in relation to bruxism., Objective: The main objective of this paper was to evaluate the connection between occlusal factors and nocturnal parafunctional activities (occlusal disharmonies and bruxism)., Method: Two groups were formed- experimental of 15 persons with signs and symptoms of nocturnal parafunctional activity of mandible (mean age 26.6 years) and control of 42 persons with no signs and symptoms of bruxism (mean age 26.3 yrs.). The computerized occlusal analyses were performed using the T-Scan II system (Tekscan, Boston, USA). 2D occlusograms were analyzed showing the occlusal force, the center of the occlusal force with the trajectory and the number of antagonistic tooth contacts., Results: Statistically significant difference of force distribution was found between the left and the right side of the arch (L%-R%) (t=2.773; p<0.02) in the group with bruxism. The difference of the centre of occlusal force - COF trajectory between the experimental and control group was not significant, but the trajectory of COF was longer in the group of bruxists (67.3+24.4mm). In addition, the significant difference of COF position in relation to the center of the elliptic fields was not found in bruxists (chi-squared=1.63; p> 0.05), but obtained results directly revealed uneven distribution of the occlusal forces which caused the excessive attrition and mobility of tooth., Conclusion: Our study failed to find direct correlation between occlusal factors and bruxism, so they are basically contributing factors.

Sleep bruxism (SB) is reported by 8% of the adult population and is mainly associated with rhythmic masticatory muscle activity (RMMA) characterized by repetitive jaw muscle contractions (3 bursts or more at a frequency of 1 Hz). The consequences of SB may include tooth destruction, jaw pain, headaches, or the limitation of mandibular movement, as well as tooth-grinding sounds that disrupt the sleep of bed partners. SB is probably an extreme manifestation of a masticatory muscle activity occurring during the sleep of most normal subjects, since RMMA is observed in 60% of normal sleepers in the absence of grinding sounds. The pathophysiology of SB is becoming clearer, and there is an abundance of evidence outlining the neurophysiology and neurochemistry of rhythmic jaw movements (RJM) in relation to chewing, swallowing, and breathing. The sleep literature provides much evidence describing the mechanisms involved in the reduction of muscle tone, from sleep onset to the atonia that characterizes rapid eye movement (REM) sleep. Several brainstem structures (e.g., reticular pontis oralis, pontis caudalis, parvocellularis) and neurochemicals (e.g., serotonin, dopamine, gamma aminobutyric acid [GABA], noradrenaline) are involved in both the genesis of RJM and the modulation of muscle tone during sleep. It remains unknown why a high percentage of normal subjects present RMMA during sleep and why this activity is three times more frequent and higher in amplitude in SB patients. It is also unclear why RMMA during sleep is characterized by co-activation of both jaw-opening and jaw-closing muscles instead of the alternating jaw-opening and jaw-closing muscle activity pattern typical of chewing. The final section of this review proposes that RMMA during sleep has a role in lubricating the upper alimentary tract and increasing airway patency. The review concludes with an outline of questions for future research.

Objective: To test the efficacy of dental treatment of bruxism on sleep quality, using slow wave sleep as the primary outcome parameter., Methods: The study design consisted of an open label, unpaired comparison between normals and patients and a paired comparison between pre- and post-treatment patient recordings. Twenty patients suffering from bruxism (13 male, 7 female, mean age 35 years) and 6 normal volunteers (3 male, 3 female, mean age 30 years) participated in the study. Polysomnographic recordings were performed in a sleep laboratory in a general hospital both before and after treatment. The treatment was derived from a model that ascribes bruxism to a dental malocclusion, and consisted solely of dental therapy (Jeanmonood 1988)., Results: The untreated bruxism group had worse sleep than normals when comparing slow wave sleep (21% versus 32% slow wave sleep percentage in sleep period time) during the second polysomnographic recording, after one night adaptation. Therapy did not improve sleep quality; bruxism patients showed only minor, non-significant differences in sleep quality when comparing pre- and post-treatment recordings.

After proposing a common-sense definition of bruxism, this partial review distills its various symptoms and consequences from the literature. That literature suggests that the splint-the most popular treatment modality-falls short in some respects. The research literature is even less sanguine about the efficacy of such other traditional therapies as sound alarms and stress reduction. Given the limited success of traditional approaches, and given, moreover, the high incidence of bruxism and its harmful consequences, clinicians may occasionally be interested in experimenting with non-intrusive, safe, less widely known, treatment modalities. To meet this need, this review-unlike all other reviews of the subject-focuses on such comparatively unpopular or recent approaches.

It is proposed that damage to the masticatory system from intense parafunction can be assessed more accurately by the Weak Link Theory. The theory predicts that the more intense and the more prolonged the forces, the more the tendency of damage to either. 1. the periodontal tissue; 2. the teeth; or 3. the orofacial structures. To test the theory, 22 subjects were selected based on reports of nocturnal bruxism. Each was assessed for masticatory system breakdown on the Russell Periodontal Index, the Helkimo Dysfunction Index, and a Tooth Wear Index. A Bruxcore (Forgione, A. 1974 J Dent Res 53:127) was used to obtain an objective score of bruxism. Five of eleven subjects with mild bruxism scored high on only one index. Significantly more subjects (ten of eleven) with moderate to severe bruxism scored high on one index only.