Mandibular Jaw Movement Automated Analysis for Oral Appliance Monitoring in Obstructive Sleep Apnea: A Prospective Cohort Study.

Rationale: Oral appliances are second-line treatments after continuous positive airway pressure for obstructive sleep apnea (OSA) management. However, the need for oral appliance titration limits their use as a result of monitoring challenges to assess the treatment effect on OSA. Objectives: To assess the validity of mandibular jaw movement (MJM) automated analysis compared with polysomnography (PSG) and polygraphy (PG) in evaluating the effect of oral appliance treatment and the effectiveness of MJM monitoring for oral appliance titration at home in patients with OSA. Methods: This observational, prospective study included 135 patients with OSA eligible for oral appliance therapy. The primary outcome was the apnea-hypopnea index (AHI), measured through in-laboratory PSG/PG and MJM-based technology. Additionally, MJM monitoring at home was conducted at regular intervals during the titration process. The agreement between PSG/PG and MJM automated analysis was revaluated using Bland-Altman analysis. Changes in AHI during the home-based oral appliance titration process were evaluated using a generalized linear mixed model and a generalized estimating equation model. Results: The automated MJM analysis demonstrated strong agreement with PG in assessing AHI at the end of titration, with a median bias of 0.24/h (limits of agreement, -11.2 to 12.8/h). The improvement of AHI from baseline in response to oral appliance treatment was consistent across three evaluation conditions: in-laboratory PG (-59.6%; 95% confidence interval, -59.8% to -59.5%), in-laboratory automated MJM analysis (-59.2%; -65.2% to -52.2%), and at-home automated MJM analysis (-59.7%; -67.4% to -50.2%). Conclusions: Incorporating MJM automated analysis into the oral appliance titration process has the potential to optimize oral appliance therapy outcomes for OSA.

Insights on mandibular jaw movements during polysomnography in obstructive sleep apnea.

A strong and specific comprehensive physiological association has been documented between mandibular jaw movements and related periods of normal or disturbed breathing across different sleep stages. The mandibular jaw movement biosignal can be incorporated in the polysomnography, displayed on the screen as a function of time like any standard polysomnography signal (eg, airflow, oxygen saturation, respiratory inductance plethysmography bands) and interpreted in the context of the target period of breathing and its associated respiratory effort level. Overall, the mandibular jaw movement biosignal that depicts the muscular trigeminal respiratory drive is a highly effective tool for differentiating between central and obstructive sleep episodes including hypopneas and for providing clinicians with valuable insights into wake/sleep states, arousals, and sleep stages. These fundamental characteristics of the mandibular jaw movement biosignal contrast with photoplethysmography, airflow, or oxygen saturation signals that provide information more about the consequence of the disturbed breathing episode than about the event itself. CITATION: Malhotra A, Martinot J-B, Pépin J-L. Insights on mandibular jaw movements during polysomnography in obstructive sleep apnea. J Clin Sleep Med. 2024;20(1):151-163.

Determinants of apnea-hypopnea index variability during home sleep testing.

BACKGROUND: A single-night attended in-laboratory polysomnography or home sleep testing are common approaches for obstructive sleep apnea (OSA) diagnosis. However, internight variability in apnea-hypopnea index value is common, and may result in misclassification of OSA severity and inapropriate treatment decisions. OBJECTIVE: To investigate factors determining short-term apnea-hypopnea index variability using multi-night automated home sleep testing, and to determine how this variability impacts clinical decisions. PATIENTS/METHODS: Adults with suspected OSA who successfully performed three home sleep tests using measurements of mandibular jaw movements (Sunrise, Namur, Belgium) combined with automated machine learning analysis were enrolled. Data analysis included principal component analysis, generalized estimating equation regression and qualitative agreement analysis. RESULTS: 160 individuals who performed three sleep tests over a mean of 8.78 ± 8.48 days were included. The apnea-hypopnea index varied by -0.88 events/h (5th-95th percentile range: -14.33 to 9.72 events/h). Based on a single-night recording, rates of overtreatment and undertreatment would have been of 13.5% and 6.0%, respectively. Regression analysis adjusted for age, sex, body mass index, total sleep time, and time between home sleep tests showed that time spent in deep non-rapid eye movement sleep and with head in supine position were independent significant predictors of the apnea-hypopnea index variability. CONCLUSIONS: At the individual level, short-term internight variability in the apnea-hypopnea index was significantly associated with time spent in deep non-rapid eye movement sleep and head in supine position. Clinical decisions based on a single-night testing may lead to errors in OSA severity classification and incorrect therapeutic decisions.

Creating an Optimal Approach for Diagnosing Sleep Apnea.

Sleep apnea is nowadays recognized as a treatable chronic disease and awareness of it has increased, leading to an upsurge in demand for diagnostic testing. Conventionally, diagnosis depends on overnight polysomnography in a sleep clinic, which is highly human-resource intensive and ignores the night-to-night variability in classical sleep apnea markers, such as the apnea-hypopnea index. In this review, the authors summarize the main improvements that could be made in the sleep apnea diagnosis strategy; how technological innovations and multi-night home testing could be used to simplify, increase access, and reduce costs of diagnostic testing while avoiding misclassification of severity.

Respiratory effort during sleep and the rate of prevalent type 2 diabetes in obstructive sleep apnoea.

AIM: To determine the association between total sleep time (TST) spent in increased respiratory effort (RE) and the prevalence of type 2 diabetes in a large cohort of individuals with suspected obstructive sleep apnoea (OSA) referred for in-laboratory polysomnography (PSG). MATERIALS AND METHODS: We conducted a retrospective cross-sectional study using the clinical data of 1128 patients. Non-invasive measurements of RE were derived from the sleep mandibular jaw movements (MJM) bio-signal. An explainable machine-learning model was built to predict prevalent type 2 diabetes from clinical data, standard PSG indices, and MJM-derived parameters (including the proportion of TST spent with increased respiratory effort [REMOV [%TST]). RESULTS: Original data were randomly assigned to training (n = 853) and validation (n = 275) subsets. The classification model based on 18 input features including REMOV showed good performance for predicting prevalent type 2 diabetes (sensitivity = 0.81, specificity = 0.89). Post hoc interpretation using the Shapley additive explanation method found that a high value of REMOV was the most important risk factor associated with type 2 diabetes after traditional clinical variables (age, sex, body mass index), and ahead of standard PSG metrics including the apnoea-hypopnea and oxygen desaturation indices. CONCLUSIONS: These findings show for the first time that the proportion of sleep time spent in increased RE (assessed through MJM measurements) is an important predictor of the association with type 2 diabetes in individuals with OSA.

Effect of Obesity on Masticatory Muscle Activity and Rhythmic Jaw Movements Evoked by Electrical Stimulation of Different Cortical Masticatory Areas.

This study investigates rhythmic jaw movement (RJM) patterns and masticatory muscle activities during electrical stimulation in two cortical masticatory areas in obese male Zucker rats (OZRs), compared to their counterparts-lean male Zucker rats (LZRs) (seven each). At the age of 10 weeks, electromyographic (EMG) activity of the right anterior digastric muscle (RAD) and masseter muscles, and RJMs were recorded during repetitive intracortical micro-stimulation in the left anterior and posterior parts of the cortical masticatory area (A-area and P-area, respectively). Only P-area-elicited RJMs, which showed a more lateral shift and slower jaw-opening pattern than A-area-elicited RJMs, were affected by obesity. During P-area stimulation, the jaw-opening duration was significantly shorter (p < 0.01) in OZRs (24.3 ms) than LZRs (27.9 ms), the jaw-opening speed was significantly faster (p < 0.05) in OZRs (67.5 mm/s) than LZRs (50.8 mm/s), and the RAD EMG duration was significantly shorter (p < 0.01) in OZRs (5.2 ms) than LZR (6.9 ms). The two groups had no significant difference in the EMG peak-to-peak amplitude and EMG frequency parameters. This study shows that obesity affects the coordinated movement of masticatory components during cortical stimulation. While other factors may be involved, functional change in digastric muscle is partly involved in the mechanism.

An Evaluation of Jaw Tracking Movements in Patients with Total Joint Replacements versus a Control Group.

Background and Objectives: One form of treatment for degenerative temporomandibular joint diseases such as osteoarthritis, rheumatic arthritis, TMJ ankylosis, and condylar resorption is total joint replacement. The aim of this study was to examine the function of the temporomandibular joint after prosthetic joint replacement. Materials and methods: Fifteen patients with unilateral or bilateral TMJ total joint replacements and 15 healthy controls were evaluated via a SICAT JMT+ device. This non-invasive system measures 3D position and linear movements in all degrees of freedom and allows undisturbed functional mandibular movements to provide a quantitative evaluation. In addition, a TMJ questionnaire consisting of the subjective symptoms was also obtained. To date, no similar studies have been cited in the literature. Results: Mandibular movements after prosthetic joint replacement were recorded during opening, closing, protrusion, and lateral excursive movements and were all significantly decreased compared to those of controls. In the treatment group, the maximum incisal opening was 33.46 ± 5.47 mm, left lateral movement was 1.91 ± 2.7 mm, right lateral movement was 1.74 ± 1.74 mm, and protrusive movement was 2.83 ± 2.05 mm. The p-value comparison study and control group indicated significant difference (p < 0.0001) between the two groups. The study group stated a high level of satisfaction with the total joint replacement. Conclusion: Within the limitations of the study, the following conclusions can be drawn: (1) TMJ replacement patients showed significantly limited jaw movements compared to the control group; (2) a small percentage of TMJ replacement patients still present low levels of pain but improved chewing ability and quality of life.

Range of motion (ROM) in the lips and jaw during vowels assessed with 3D motion analysis in Swedish children with typical speech development and children with speech sound disorders.

PURPOSE: The aim was to compare movement patterns of lips and jaw in lateral, vertical and anteroposterior directions during vowel production in children with typical speech development (TSD) and in children with speech sound disorders (SSD) persisting after the age of six. METHODS: A total of 93 children were included, 42 children with TSD (6:0-12:2 years, mean age 8:9 ± 1:5, 19 girls and 23 boys) and 51 children with SSD (6:0-16:7 years, mean age 8:5 ± 3:0, 14 girls and 37 boys). Range of motion (ROM) in lips and jaw in the vowels [a, ʊ, ɪ] produced in a syllable repetition task and median values in resting position were measured with a system for 3D motion analysis. The analysis was based on the coordinates for the mouth corners and the chin centre. RESULTS: There were significant differences between the groups on movements in lateral direction in both lips and jaw. Children with TSD had generally smaller and more, symmetrical movements in the lips and jaw, in all three dimensions compared to children with SSD. There were no significant differences between the groups in resting position. CONCLUSION: Children with SSD persisting after the age of six years show more asymmetrical and more variable movement patterns in lips and jaw during vowel production compared with children with TSD in a simple syllable repetition task. Differences were more pronounced in lateral direction in both lips and jaw.

Blockade of adenosine A2A receptors inhibits Tremulous Jaw Movements as well as expression of zif-268 and GAD65 mRNAs in brain motor structures.

Tremor is one of the motor symptoms of Parkinson's disease (PD), present also in neuroleptic-induced parkinsonism. Tremulous Jaw Movements (TJMs) are suggested to be a well-validated rodent model of PD resting tremor. TJMs can be induced by typical antipsychotics and are known to be reduced by different drugs, including adenosine A2A receptor antagonists. The aim of the present study was to search for brain structures involved in the tremorolytic action of SCH58261, a selective A2A receptor antagonist, in TJMs induced by subchronic pimozide. Besides TJMs, we evaluated in the same animals the expression of zif-268 mRNA (neuronal responsiveness marker), and mRNA levels for glutamic acid decarboxylase 65-kDa isoform (GAD65) and vesicular glutamate transporters 1 and 2 (vGluT1/2) in selected brain structures, as markers of GABAergic and glutamatergic neurons, respectively. We found that SCH58261 reduced the pimozide-induced TJMs. Pimozide increased the zif-268 mRNA level in the striatum, nucleus accumbens (NAc) core, and substantia nigra pars reticulata (SNr). Additionally, it increased GAD65 mRNA in the striatum and SNr, and vGluT2 mRNA levels in the subthalamic nucleus (STN). A positive correlation between zif-268, GAD65 and vGluT2 mRNAs and TJMs was found. SCH58261 reversed the pimozide-increased zif-268 mRNA in the striatum and NAc core and GAD65 mRNA in the striatum and SNr. In contrast, SCH58261 did not influence vGluT2 mRNA in STN. The present study suggests an importance of the striato-subthalamo-nigro-thalamic circuit in neuroleptic-induced TJMs. The tremorolytic effect of A2A receptor blockade seems to involve this circuit bypassing, however, STN.

Visualization of mandibular movement relative to the maxilla during mastication in mice: integration of kinematic analysis and reconstruction of a three-dimensional model of the maxillofacial structure.

BACKGROUND: Mastication is one of the most fundamental functions for the conservation of human life. To clarify the pathogenetic mechanism of various oral dysfunctions, the demand for devices for evaluating stomatognathic function has been increasing. The aim of the present study was to develop a system to reconstruct and visualize 3-dimensional (3D) mandibular movements relative to the maxilla, including dynamic transition of occlusal contacts between the upper and lower dentitions during mastication in mice. METHODS: First, mandibular movements with six degrees of freedom were measured using a motion capture system comprising two high-speed cameras and four reflective markers. Second, 3D models of maxillofacial structure were reconstructed from micro-computed tomography images. Movement trajectories of anatomical landmark points on the mandible were then reproduced by integrating the kinematic data of mandibular movements with the anatomical data of maxillofacial structures. Lastly, 3D surface images of the upper dentition with the surrounding maxillofacial structures were transferred to each of the motion capture images to reproduce mandibular movements relative to the maxilla. We also performed electromyography (EMG) of masticatory muscles associated with mandibular movements. RESULTS: The developed system could reproduce the 3D movement trajectories of arbitrary points on the mandible, such as incisor, molars and condylar points with high accuracy and could visualize dynamic transitions of occlusal contacts between upper and lower teeth associated with mandibular movements. CONCLUSIONS: The proposed system has potential to elucidate the mechanisms underlying motor coordination of masticatory muscles and to clarify their roles during mastication by taking advantage of the capability to record EMG data synchronously with mandibular movements. Such insights will enhance our understanding of the pathogenesis and diagnosis of oral motor disorders by allowing comparisons between normal mice and genetically modified mice with oral behavioral dysfunctions.

Effects of preventing intercuspation on the precision of jaw movements.

BACKGROUND: Closing movements are among the jaw's basic physiological motor actions. During functional movements, the jaw changes position continually, which requires appropriate proprioception. However, the significance of the various proprioceptive receptors involved and how they interact is not yet fully clear. OBJECTIVES: This study's main objective was to test whether preventing intercuspation (IC) for 1 week would affect the precision of jaw-closing movements into IC and the functional space of habitual chewing movements (HCM). A secondary objective was to compare precision of jaw-closing movements into IC with the precision of movements into a target position (TP) far from IC. METHODS: Fourteen participants' HCM and jaw-closing movements into IC were recorded on two sessions (T1 and T2) 1 week apart. Between sessions, participants wore posterior bite plates to prevent IC. They also received a 10-minute training session at T1 to guide their jaw-closing movements into TP. The precision of the closing movements into IC and TP was analysed. For HCM, the vertical amplitude, lateral width and area of chewing cycles were evaluated. RESULTS: The precision of jaw movements into IC increased as the jaw gap decreased, but precision did not differ significantly between T1 and T2. For HCM, the vertical amplitude and area of chewing cycles increased significantly between T1 and T2. The precision of the closing trajectory into TP increased significantly during the training session. CONCLUSION: Our results confirm the excellent adaptability of the craniomandibular system, controlled by stringent motor programmes that are supported by continuous peripheral sensory input.

Heart rate changes associated with rhythmic masticatory muscle activities and limb movements in sleep bruxers: Preliminary findings.

Objective: To investigate the relationship of rhythmic masticatory muscle activities (RMMAs) and limb movements (LMs) with heart rate (HR) acceleration. Methods: The amplitude and duration of HR increases, the time to reach peak HR associated with RMMAs/LMs during sleep, duration of movement events, and their relationships with cortical arousal levels were determined in 9 sleep bruxers and 10 normal controls. Results: A total of 48.15% and 49.44% HR increased before the onset of RMMAs/LMs in the sleep bruxers and controls, respectively. All of the parameters of HR increases were significantly different between the sleep bruxers and the controls (p < 0.05-0.001) and between different cortical arousal levels (p < 0.01), and the duration of RMMAs/LMs was positively correlated with the parameters (Sleep bruxers: r2 = 0.18-0.88, p < 0.0001; Controls: r2 = 0.16-0.78, p < 0.0001). Discussion: These data suggest the HR increases are associated with the movement events and changes in cortical arousal levels in the sleep bruxers and controls. Abbreviations: LMs: Limb movements; HR: Heart rate; RMMAs: Rhythmic masticatory muscle activities; SB: Sleep bruxism; PSG: Polysomnographic; EEG: Electroencephalographic; PLMS: Periodic leg movements; SSRIs: Selective serotonin reuptake inhibitors; ECG: Electrocardiographic; EOG: Electrooculographic; EMG: Electromyographic; SD: Standard deviation; Fig: Figure; SEM: Standard error of mean; N1: Non-rapid eye movement sleep stage 1; N2: Non-rapid eye movement sleep stage 2; N3: Non-rapid eye movement sleep stage 3; REM: Rapid eye movement ; NA: No arousal; mAR: Microarousal; AW: Awakening.

Suppression of the Swallowing Reflex during Rhythmic Jaw Movements Induced by Repetitive Electrical Stimulation of the Dorsomedial Part of the Central Amygdaloid Nucleus in Rats.

A previous study indicated that the swallowing reflex is inhibited during rhythmic jaw movements induced by electrical stimulation of the anterior cortical masticatory area. Rhythmic jaw movements were induced by electrical stimulation of the central amygdaloid nucleus (CeA). The swallowing central pattern generator is the nucleus of the solitary tract (NTS) and the lateral reticular formation in the medulla. Morphological studies have reported that the CeA projects to the NTS and the lateral reticular formation. It is therefore likely that the CeA is related to the control of the swallowing reflex. The purpose of this study was to determine if rhythmic jaw movements driven by CeA had inhibitory roles in the swallowing reflex induced by electrical stimulation of the superior laryngeal nerve (SLN). Rats were anesthetised with urethane. The SLN was solely stimulated for 10 s, and the swallowing reflex was recorded (SLN stimulation before SLN + CeA stimulation). Next, the SLN and the CeA were electrically stimulated at the same time for 10 s, and the swallowing reflex was recorded during rhythmic jaw movements (SLN + CeA stimulation). Finally, the SLN was solely stimulated (SLN stimulation following SLN + CeA stimulation). The number of swallows was reduced during rhythmic jaw movements. The onset latency of the first swallow was significantly longer in the SLN + CeA stimulation than in the SLN stimulation before SLN + CeA stimulation and SLN stimulation following SLN + CeA stimulation. These results support the idea that the coordination of swallowing reflex with rhythmic jaw movements could be regulated by the CeA.

Functional Analysis of Rhythmic Jaw Movements Evoked by Electrical Stimulation of the Cortical Masticatory Area During Low Occlusal Loading in Growing Rats.

The maturation of rhythmic jaw movements (RJMs) and related neuromuscular control has rarely been studied in animals, though this process is essential for regulating the development of stomatognathic functions. Previous studies have shown that occlusal hypofunction during growth alters masticatory performance. However, little is known about patterns of cortically-induced RJMs under conditions of soft-diet feeding during development. The aim of this study is to clarify the effect of low occlusal loading on the pattern of cortically induced RJMs and related neuromuscular responses in growing rats. Sixty-four 2-week-old male albino Wistar rats were randomly divided into two groups and fed on either a normal diet (control) or soft diet (experimental) soon after weaning. At 5, 7, 9, and 11 weeks of age, electromyographic (EMG) activity was recorded from the right masseter and anterior digastric muscles along with corresponding kinematic images in RJMs during repetitive intracortical microstimulation of the left cortical masticatory area (CMA). Rats in both groups showed an increase in gape size and lateral excursion until 9 weeks of age. The vertical jaw movement speed in both groups showed no significant difference between 5 and 7 weeks of age but increased with age from 9 to 11 weeks. Compared to the control group, the average gape size and vertical speed were significantly lower in the experimental group, and the pattern and rhythm of the jaw movement cycle were similar between both groups at each recording age. EMG recordings showed no age-related significant differences in onset latency, duration, and peak-to-peak amplitude. Moreover, we found significantly longer onset latency, smaller peak-to-peak amplitude, and greater drop-off mean and median frequencies in the experimental group than in the control group, while there was no significant difference in the duration between groups. These findings indicate that a lack of enough occlusal function in infancy impedes the development of patterns of RJMs and delays the neuromuscular response from specific stimulation of the CMA.

Eye movements in relation to rhythmic masticatory muscle activities in patients with sleep bruxism.

OBJECTIVES: To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB). METHODS: Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed. RESULTS: During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls. CONCLUSIONS: Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls.

Multimodal Sensory Stimulation of the Masseter Muscle Reduced Precision but Not Accuracy of Jaw-Opening Movements.

A functional integration between the trigeminal and craniocervical sensorimotor systems has been demonstrated, with simultaneous jaw and head-neck movements during jaw opening-closing. We previously showed that pain induction in the masseter muscle increased the relative contribution of the neck component of integrated jaw-neck movements. Induced pain or manipulation of proprioception by vibration did not affect accuracy during a jaw-opening task in men. It is not known how multimodal sensory stimulation, with a combination of pain induction and vibration, affects jaw-opening accuracy and precision. The aim was to investigate how jaw-neck movements, and specifically accuracy and precision of jaw-opening, are affected during concomitant nociceptive and proprioceptive stimulation of the masseter muscle. Twenty-one healthy men performed jaw-opening to a target position, defined as 75% of individual maximum jaw opening, during control (Ctr), vibration of masseter muscles (Vib), pain induction in the masseter (Pain), and concomitant vibration and pain induction in the masseter muscle (VibPain). Simultaneous jaw and head movements were recorded with an optoelectronic system and amplitudes calculated for each jaw opening-closing cycle. Accuracy of jaw movements was defined as the achievement of the target position. Precision of jaw movements was defined as the cycle-to-cycle variability from the mean of cycles 2-10 (coefficient of variation, CV). Differences between the trials were analyzed with Friedman's test, Dunn's test, and Benjamini-Hochberg correction. There were no significant differences between the trials for jaw movement amplitudes. For head movements, amplitudes for cycles 2-10 were larger during Pain compared to Ctr and Vib (both p = 0.034), and larger during VibPain compared to Ctr (p = 0.034) and Vib (p = 0.035). There were no differences in accuracy of jaw movements between the trials. For precision of jaw movements, the cycle-to-cycle variability was larger during VibPain compared to Ctr (p = 0.027) and Vib (p = 0.018). For integrated jaw-neck motor strategy, there was a difference between pain and non-pain trials, but no differences between unimodal and multimodal stimulation trials. For achievement of jaw-opening to a target position, the results show no effect on accuracy, but a reduced precision of jaw movements during combined proprioceptive and nociceptive multimodal stimulation.

Development and evaluation of a jaw-tracking system for mice: reconstruction of three-dimensional movement trajectories on an arbitrary point on the mandible.

BACKGROUND: Mastication is one of the most fundamental functions for the conservation of life. The demand for devices for evaluating stomatognathic function, for instance, recording mandibular movements or masticatory muscle activities using animal models, has been increasing in recent years to elucidate neuromuscular control mechanisms of mastication and to investigate the etiology of oral motor disorders. To identify the fundamental characteristics of the jaw movements of mice, we developed a new device that reconstructs the three-dimensional (3D) movement trajectories on an arbitrary point on the mandible during mastication. METHODS: First, jaw movements with six degrees of freedom were measured using a motion capture system comprising two high-speed cameras and four reflective markers. Second, a 3D model of the mandible including the markers was created from micro-computed tomography images. Then, the jaw movement trajectory on the certain anatomical point was reproduced by integrating the kinematic data of the jaw movements with the geometric data of the mandible. RESULTS: The 3D movements at any points on the mandible, such as the condyle, molar, and incisor during mastication, could be calculated and visualized with an accuracy > 0.041 mm in 3D space. The masticatory cycle was found to be clearly divided into three phases, namely, the opening, closing, and occlusal phases in mice. CONCLUSIONS: The proposed system can reproduce and visualize the movements of internal anatomical points such as condylar points precisely by combining kinematic data with geometric data. The findings obtained from this system could facilitate our understanding of the pathogenesis of eating disorders or other oral motor disorders when we could compare the parameters of stomatognathic function of normal mice and those of genetically modified mice with oral behavioral dysfunctions.

Characterisation of the relationships between rhythmic masticatory muscle activities and limb movements in patients with sleep bruxism.

BACKGROUND: Most rhythmic masticatory muscle activities (RMMAs) have been shown to be accompanied with limb movements (LMs) in sleep bruxism (SB) patients during sleep. OBJECTIVES: To compare the relationships between RMMAs and LMs in SB patients and normal subjects. METHODS: Polysomnographic recordings were performed on eight SB patients and nine normal subjects and the frequencies and durations of RMMAs as well as LMs were determined. Linear regression and correlation analysis were performed to study the relationship between durations of RMMAs and LMs when RMMAs occurred with LMs. RESULTS: Most LMs in SB patients, but not in normal subjects, were accompanied with RMMAs. RMMAs in SB patients were more likely to be isolated, phasic or mixed, while RMMAs in normal subjects were more likely to be tonic. The frequencies of LMs, isolated RMMAs and RMMAs accompanied with LMs in SB patients were significantly higher than those in normal subjects. Furthermore, linear regression and correlation analysis showed that duration of RMMAs was significantly associated with that of LMs when RMMAs occurred with LMs. The duration of RMMAs, when accompanied with LMs, in SB patients was significantly longer than that in normal subjects. CONCLUSIONS: Close relationships between LMs and RMMAs exist in SB patients and normal subjects, and SB episodes may be part of cortical arousal responses and the increased cortical activities associated with SB episodes may not just be localised to the central nervous system (CNS) that controls jaw movements but may also include other parts of CNS that controls LMs.

The effect of unilateral lingual nerve injury on the kinematics of mastication in pigs.

OBJECTIVE: This study evaluates the effect of unilateral lingual sensory loss on the spatial and temporal dynamics of jaw movements during pig chewing. DESIGN: X-ray Reconstruction of Moving Morphology (XROMM) was used to reconstruct the 3-dimensional jaw movements of 6 pigs during chewing before and after complete unilateral lingual nerve transection. The effect of the transection were evaluated at the temporal and spatial level using Multiple Analysis of Variance. Temporal variables include gape cycle and phase durations, and the corresponding relative phase durations. Spatial variables include the amplitude of jaw opening, jaw yaw, and mandibular retraction-protraction. RESULTS: The temporal and spatial dynamics of jaw movements did not differ when chewing ipsilateral versus contralateral to the transection. When compared to pre-transection data, 4 of the 6 animals showed significant changes in temporal characteristics of the gape cycle following the transection, irrespective of chewing side, but the specific response to the lesion was highly dependent on the animal. On the other hand, in affected individuals the amplitude of jaw movements was altered similarly in all 3 dimensions: jaw opening and protraction-retraction increased whereas jaw yaw decreased. CONCLUSION: The variable impact of this injury in this animal model suggests that individuals use different compensatory strategies to adjust or maintain the temporal dynamics of the gape cycle. Because the amplitude of jaw movements are more adversely affected than their timing, results suggest that maintaining the tongue-jaw coordination is critical and this can come at the expense of bolus handling and masticatory performance.

Alteraciones del sueño y bruxismo / Sleep alterations and bruxism

El sueño es un requerimiento biológico para la vida, sus alteraciones o su ausencia pueden disminuir la calidad de vida, el estado anímico y funcional, afectando seriamente la salud. Un sueño placentero y reparador implica cursar por facetas de profundidad diversa y actividad neuronal compleja. En este artículo se intentan explicar las generalidades del proceso del sueño y algunos de sus trastornos que lo relacionan con aumento de la actividad de los músculos masticatorios (bruxismo). Son presentados aspectos clínicos y neuronales que inducen a un incremento de microdespertares como alteración del sueño, estimulando bruxismo nocturno y bruxismo asociado a apnea nocturna. Son discutidas las posibles relaciones bidireccionales entre bruxismo diurno y nocturno secundarias a modifi caciones en la cantidad y calidad del proceso del sueño. De la misma manera, son sugeridas algunas consideraciones semiológicas y nosológicas para el mejor manejo y control del bruxismo asociado a las alteraciones del sueño, bajo el diagnóstico, atención y supervisión de equipos de atención multi- e interdisciplinarios (AU)

Sleep is a biological requirement for life, its alterations or privation thereof may reduce a person's quality of life, his or her state of mind and physical functions, which signifi cantly aff ects their health. Pleasant and repairing sleep implies going through variable deepness sleep stages, and a complex neuronal activity. This article intends to explain the generalities of the sleep process and certain disorders, particularly those in connection with the activity of the mastication muscles (bruxism). Clinical and neuronal aspects are presented inducing an increase in micro-awakenings such as sleep alterations stimulating nocturnal and bruxism associated with sleep apnea. Bidirectional connections between diurnal and nocturnal bruxism are argued as secondary to changes in the amount and quality of the sleep process. In the same manner, certain considerations associated to semiology and nosology of the diverse bruxism manifestations are considered for the better handling and control of the bruxism associated with sleep alterations under the diagnosis attention and supervision of multi- and interdisciplinary teams (AU)