Association between the amount of alcohol intake and masseter muscle activity levels recorded during sleep in healthy young women

PURPOSE: The aim of this study was to determine if the amount of alcohol intake is associated with masseter muscle activity recorded during sleep. MATERIALS AND METHODS: Sixty healthy young female subjects (average age, 23.0 +/- 1.9 years; range, 21 to 32 years) participated in the study. Subjects were asked to perform 6 consecutive nightly masseter electromyography (EMG) recordings by using a portable EMG recording system in their homes. Using a minimum threshold criterion, which was set at 20% of the maximum voluntary contraction level, the total duration of muscle activity per hour of sleep was calculated. EMG data obtained on the first night were excluded from the analysis to avoid the first-night effect, and the data of the remaining 5 nights were averaged. Further, the subjects were asked to fill out questionnaires regarding their daily alcohol intake during the recording period. The total ethanol content of the consumed alcohol was calculated using a standard conversion table for alcoholic beverages. The ethanol concentration of each type of alcohol was multiplied by the reported amount consumed on each day, and the average value for 5 days was calculated. The EMG data were considered as a dependent variable, while the alcohol data were considered as an independent variable. Linear regression analysis was used to assess a possible association between these variables. RESULTS: The subjects who did not consume alcohol during the recording period (n = 28) or who provided incomplete data sets as a result of missing data (n = 9) were excluded. The data of the remaining 23 subjects (n = 23) were exclusively analyzed. The result of this analysis revealed that the total ethanol content of the consumed alcohol was significantly and positively related to the EMG duration variable (coefficient = 0.51, 95% confidence interval: 0.20 to 0.82, adjusted R2 = 0.33, P < .01). CONCLUSION: The results suggest that the amount of alcohol intake is substantially associated with masseter muscle activity levels during sleep in young women.     

Prevalence of signs and symptoms of temporomandibular disorders in young Nigerian adults

The objective of this study was to determine the prevalence of signs and symptoms of TMD in young Nigerian adults and to establish a baseline for comparison with other studies. It consisted of a cross-sectional study at Obafemi Awolowo University, Ile-Ife, Nigeria in 1997. The subjects consisted of 308 medical and dental students (207 males and 101 females) randomly selected from a Nigerian University. Their ages ranged from 17 to 32 years with a mean age of 23 +/- 3.0 years. They were assessed according to the criteria of Helkimo (1974). Whilst 26.3 per cent of the subjects reported mild symptoms (Ai I) of TMD, only 2.9 per cent reported severe symptoms (Ai II). Similarly, 46 per cent showed mild dysfunction signs (Di I), whilst 16.5 and 0.3 per cent exhibited moderate (Di II) and severe (Di III) signs of TMD, respectively. No significant relationships were found between sex, anamnestic index, and the clinical dysfunction index scores. However, there were low but significant correlations between ananmestic index scores (Ai) and the recorded signs (Di), as well as the clinical dysfunction scores (CDS). There is some evidence to show that signs and symptoms of TMD occur amongst Nigerians, although restricted lateral and protrusive mandibular movements contributed significantly to clinical dysfunction scores. This report contrasts with what is found in western societies regarding the low prevalence of TMJ pain. Refereed Scientific Paper     

Association between oral habits and signs/symptoms of temporomandibular disorders in Flemish adolescent girls

The influence of oral habits on the development of signs and symptoms of temporomandibular disorders (TMD) and pain is unclear. The prevalence and nature of such oral habits may also vary geographically. The aim of the present study was to assess the prevalence of parafunctions in Flemish adolescent girls and to study the interrelationship with TMD. A group of 261 school girls (15–16 years of age) participated. A questionnaire used in a similar study ( Gavish et al., 2000 ) was translated and inquired for oral habits (chewing of gum, nails or foreign objects, eating of seeds, crushing of ice or food, continuous leaning on the arm, daytime or night‐time grinding or clenching, jaw play, unilateral chewing) and TMD symptoms (joint noises, catching or locking, joint or muscle pain, tension or fatigue in the muscles). A brief clinical examination was performed by a single examiner: active and passive maximal mouth opening, presence of joint sounds, palpation tenderness of the lateral poles of the joints and of the masseter and anterior temporalis muscles, extent of abrasion of the canines, tongue or cheek imprints. Statistical evaluation used Spearman correlation, chi‐squared analysis and multiple regression analysis. The intra‐examiner reproducibility was moderate to high (κ 0·6–0·8 – Spearman Correlation 0·99 for maximal mouth opening). The frequency of reported oral habits was high: leaning on the arm (98%), gum chewing (89%, mean duration 3 h day^?1), lip‐ (62·1%) and cheek‐biting (41%), ice‐crushing (30%). There was a significant (P < 0·0001) but weak (0·30) positive correlation between the number of oral habits and the number of symptoms. Internal derangements were significantly (P < 0·0001) but weakly (0·25) correlated with jaw play and other oral habits. There was no relation between tooth clenching and myogenous pain (χ², P=0·31, but only 27% power). Multiple regression analysis showed that the number of symptoms increased by 52% if the subject reported ‘jaw play’, by 24% if chewing gum more than 2 h day^?1, by 28% while cheek biting and by 25% if chewing unilaterally.     

Prevalence of signs and symptoms of temporomandibular disorders in a young male Saudi population

SUMMARY The aim of the present study was to investigate the prevalence of temporomandibular disorders (TMD) in a selected young male Saudi population. The material comprised 105 dental students having a mean age of 23 years within the range of 20–29 years. A functional evaluation of the stomatognathic system was performed using the Helkimo anamnestic and clinical dysfunction index. Almost two-thirds of the individuals had no sings and symptoms of TMD. Thirty per cent of the individuals reported mild dysfunction (A_i I) and 6% had severe symptoms (A_i II). Thirty—three per cent showed mild clinical signs of dysfunction (D_i I) and 3% had signs of moderate dysfunction (D_i II). Only 1% exhibited severe clinical signs (D_i III). While the individuals represented a non-Western population, the prevalence of signs and symptoms of temporomandibular disorders compared favourably to that found in Western countries, at least as regards to reported symptoms.     

Association between generalized joint hypermobility and signs and diagnoses of temporomandibular disorders

The aim of this study was to analyze whether generalized joint hypermobility (GJH) is a risk factor for temporomandibular disorders (TMD). We examined 895 subjects (20–60 yr of age) in a population‐based cross‐sectional sample in Germany for GJH according to the Beighton classification and for TMD according to the Research Diagnostic Criteria for TMD (RDC/TMD). After controlling for the effects of age, gender, and general joint diseases using multiple logistic regression analyses, hypermobile subjects (with four or more hypermobile joints on the 0–9 scale) had a higher risk for reproducible reciprocal clicking as an indicator for disk displacement with reduction (Odds Ratio (OR) = 1.68) compared with those subjects without hypermobile joints. Concurrently, subjects with four or more hypermobile joints had a lower risk for limited mouth opening (< 35 mm; OR = 0.26). The associations between GJH and reproducible reciprocal clicking or limited mouth opening were statistically significant in a trend test. No association was observed between hypermobility and myalgia/arthralgia (RDC/TMD Group I/IIIa). In conclusion, GJH was found to be associated with non‐painful subtypes of TMD.     

Relationship between mandibular position and the coordination of masseter muscle activity during sleep in humans

Although bruxism has been regarded as having a possibly important role in the aetiology of craniomandibular disorders, the activity of masticatory muscles relative to mandibular position during sleep grinding as recorded by electromyography (EMG) has not yet been clarified. Surface EMGs of the bilateral superficial masseter muscles were recorded simultaneously with mandibular position during sleep from 12 volunteers for three consecutive nights. The incidence of two mandibular positions were recorded with magnetic sensors for both left- and right-sided mandibular grinding. One of the mandibular positions was the canine edge-to-edge position, and the other was the midpoint between the intercuspal position and the canine edge-to-edge position. The mode of the working/balancing activity ratio ranged from 1/10 to 2/10, showing the marked predominance of balancing side masseter muscle activity during sleep grinding. During sleep grinding, EMG bursts of masseter muscle were observed mainly with mediotrusive mandibular movement from the canine edge-to-edge position. From the results of the present study, it is suggested that muscular dynamics during sleep are unique compared to that during voluntary clenching, and exert a greater mechanical load to the balancing side temporomandibular joint.     

The relationship between signs and symptoms of temporomandibular disorders and bilateral occlusal contact patterns during lateral excursions

The relationship between signs and symptoms of temporomandibular disorders (TMD) and bilateral occlusal contact patterns was investigated in 143 TMD patients (mean age: 34·0 ± 15·9 years; 38 male and 105 female). In addition to an interview regarding chief complaints and accompanying symptoms various muscles and the temporomandibular joints were palpated bilaterally and occlusal analyses were made. Only 5 out of 108 paired variables were found to be significantly associated by using the chi‐squared test. Medial pterygoid muscle pain on palpation showed significant associations with the occlusal contact pattern ( P < 0·005), especially working side contacts (interocclusal tooth contacts on the working side) ( P < 0·005), during contralateral excursions; sternocleidomastoid muscle pain on palpation showed a significant association with balancing side contacts (interocclusal tooth contacts on the balancing side) during ipsilateral excursions P < 0·05); shoulder stiffness and pain in the eye showed significant associations with balancing side contacts during contralateral excursions ( P < 0·05). The results show only a weak relationship between some TMD symptomatology and bilateral occlusal contact patterns during lateral excursions. The findings suggesting the specific laterality of a few TMD signs and symptoms associated with particular occlusal contacts may deserve closer case–control study.     

Blood oxygenation of masseter muscle during sustained elevated muscle activity in healthy participants

Myofascial pain associated with temporomandibular disorders has often been linked to pathological muscle hyperactivity. As a result, localised disturbances of intramuscular blood flow could lead to a lower level of oxygen distribution, hypoxia and microcirculatory changes. To assess haemodynamic changes in the masseter muscle during sustained elevated muscle activity (SEMA). Sixteen healthy participants performed thirty 1‐min bouts of SEMA with intervals of 1‐min ‘rest’ periods between the bouts on a bite force transducer device. The participants completed three sessions with different percentage of their maximal voluntary occlusal bite force (MVOBF): 0% (no task), 10% or 40% MVOBF tasks. The order of the sessions was randomised with 1‐ to 2‐week intervals. Haemodynamic characteristics of the masseter muscle were estimated with use of a laser blood oxygenation monitor. Tissue blood oxygen saturation (StO₂) during SEMA was lower than during rest (P < 0·001). The relative changes in total haemoglobin (Total‐Hb) and StO₂ were influenced by condition (SEMA and rest) and with interactions between condition and session (0%, 10% and 40% MVOBF tasks). These results suggest that SEMA may lead to hypoxia in the masseter muscle and that the haemodynamic characteristics and muscle symptoms depend on the magnitude of muscle contractions. Overall, the present findings may help to provide better insights into relationships between jaw muscle activity, haemodynamic changes and symptom developments with implications for clinical conditions such as bruxism characterised by different levels of tooth‐grinding and tooth‐clenching muscle activity.     

Relationship between the frequency of sleep bruxism and the prevalence of signs and symptoms of temporomandibular disorders in an adolescent population

PURPOSE: The relationship between sleep bruxism (SB) and temporomandibular disorders (TMD) is unclear. This study aimed to estimate SB prevalence in an adolescent population and to investigate the relationship between SB frequency and prevalence of TMD signs/symptoms. MATERIALS AND METHODS: First-year students at a high school in Okayama, Japan, were recruited in 2005, with 195 subjects responding. The SB detection device was a miniature disposable device (BiteStrip, SLP) that indicated the total SB events per night on a 4-grade score. The subjects were divided into severe and nonsevere SB groups with SB frequency cutoffs. The subjects were examined for temporomandibular joint (TMJ) noise during mouth opening/closing, tenderness of the masticatory/cervical muscles, and range of TMJ condylar movement. The presence/absence of headache and shoulder stiffness was also determined by the interview. The odds ratio (OR) and confidence interval (CI) were calculated to test the relationship between SB frequency, gender difference, and presence of the TMD signs/symptoms by multiple regression analysis. RESULTS: Severe SB (more than 125 events per night) was significantly related to the presence of TMJ clicking (OR: 3.74, CI: 1.22-11.49, P = .02), while gender (male) was not related to the presence of TMJ clicking. Severe SB was not related to headache, though gender (male) was significantly related to headache (OR: 2.52, Cl: 1.04-6.11, P= .04) in these subjects. CONCLUSION: These results suggest that the presence of TMJ clicking was closely related to severe SB in an adolescent population.     

The prevalence and treatment needs of symptoms and signs of temporomandibular disorders among young adult males

A temporomandibular disorder (TMD) screening history and screening examination was performed on 523 young adult males. The screening forms were similar to those TMD forms developed and formulated under the auspices of the American College of Prosthodontists. In turn, the substance of the latter forms was initially derived from the recommendations of the President's TMD Conference of the American Dental Association, with 62 eminent researchers, educators and clinicians as participants. Each subject was given a TMD self-administered screening history form to complete, formatted in a check - the block format. It included all items considered to be classic TMD symptoms. The screening examination was performed extraorally and included (i) range of jaw movement, (ii) digital palpation of selected masticatory muscles and palpation over the pre-auricular temporomandibula joint (TMJ) area and (iii) digital palpation for TMJ sounds during jaw movement. The subjects were categorized into the following four categories: 0 = no symptoms/signs, 1 = insignificant moderate symptoms and/or signs, 2 = significant moderate symptoms and/or signs, and 3 = severe symptoms and/or signs. The overall results showed that 75% of the subjects had TMD symptoms and/or signs. There were 6.9% in category 1, 51.4% in category 2, and 16.7% in category 3. It was recommended that subjects in category 2 and 3 should have a comprehensive TMD evaluation, in order to further identify the recommended need for TMD Therapy.     

Effect of experimental stress on masseter and temporalis muscle activity in human subjects with temporomandibular disorders

Temporomandibular (TM) disorders have an uncertain aetiology. The purpose of this study was to replicate and extend the work of Yemm (1969) (Archs oral Biol. 14, 873-878, 1437-1439; Br. dent. J. 127, 508-510), who reported a lack of habituation to experimentally induced stress in subjects with TM disorders. In this study, 20 TM disorder patients and 20 controls, matched for age and sex, performed a timed psychomotor task while bilateral masseter and anterior temporalis electromyographic (EMG) activity, finger temperature and skin admittance were monitored. These data were sampled, stored every 4s and averaged by an Apple II Plus/ISAAC interface. A significant trials effect for finger temperature (F[4/152] = 34.99, p less than 0.001) and skin admittance (F[4/152] = 41.90, p less than 0.001) was found, suggesting that the independent variable (stress) had been successfully manipulated. A significant trials by groups effect was found for right temporalis EMG activity (F[3/144] = 3.94, p less than 0.05); the left temporalis showed a similar, but not significant, trend. The masseter muscles did not show differences or trends between groups. No significant differences were found in resting EMG levels or in the initial magnitude of EMG responses during baseline. These results provide support for the hypothesis that TM disorder and control groups respond differently to stress in terms of habituation to stressful stimuli.     

Effect of interocclusal appliance on bite force,sleep quality,salivary cortisol levels and signs and symptoms of temporomandibular dysfunction in adults with sleep bruxism

ObjectiveThe purpose was to evaluate the effect interocclusal appliance therapy on bite force (BF), sleep quality and salivary cortisol levels in adults with SB diagnosed by polysomnography. As a secondary aim, signs and symptoms of temporomandibular dysfunction (TMD) were evaluated.DesignForty-three adults (19–30 y/o) were divided into two groups: experimental group (G_SB), composed of 28 subjects with SB, and control group (G_C), without SB and TMD (n = 15). G_SB was treated with stabilization interocclusal splint and evaluated at time intervals: before (baseline), one month (T1) and two months (T2) after therapy began, to collect data related to BF, sleep quality (Pittsburgh Sleep Quality Index), salivary cortisol levels and TMD. G_C was also examined three times and received no therapy. Data were analysed by means of normality tests, t-test/Mann-Whitney and One-way ANOVA repeated measures (Tukey post-test). Two-way ANOVA test for repeated measures was applied to verify the effect time*group interaction on the variance of each dependent variable (α = 0.05).ResultsG_SB showed an increase in BF and a positive effect on muscular symptomatology, range of mandibular movements and sleep quality; in G_C these parameters did not differ. Cortisol concentration decreased between baseline and T1 in G_SB (F_(1,31) = 4.46; test power = 62%; p = 0.017). The variance observed for BF, TMD and sleep quality among time points was dependent on the group (moderate effect size: partial Eta square >0.16; test power >80%).ConclusionsThe results suggested that short-term interocclusal appliance therapy had a positive effect on BF, temporomandibular symptomatology, sleep quality and salivary cortisol levels in adults with SB.     

Perceived malocclusion and other teeth-associated signs and symptoms in temporomandibular disorders

This article reports the results of a clinical study that evaluated adjunctive teeth-associated signs and symptoms before and after nonsurgical temporomandibular disorder therapy. Eighty-nine patients were referred to a private prosthodontic practice in the Washington, DC metropolitan area. Of the 89 patients, 75 were selected for the clinical study after completing the interview, history, and clinical examination. The major signs and symptoms were recorded, along with adjunctive teeth-associated signs and symptoms. The treatment included an anterior programming device, a centric relation occlusal device, and, when indicated, a selective occlusal equilibration. The results were recorded after five treatment visits. Of 75 patients, 67 made good-to-excellent improvement in the signs and symptoms of their major temporomandibular disorder. Patients with adjunctive teeth-associated signs and symptoms demonstrated a marked reduction in these signs and symptoms as assessed by their mental perception and verbal feedback. The symptoms of perceived awareness of malocclusion were not resolved with centric relation occlusal device therapy in 22 of the 24 patients with this symptom. However, excellent improvement was noted in this symptom when occlusal device therapy was followed by a selective occlusal equilibration. Thirty-eight patients in this study had difficulty in making lateral gliding articulation movements with the occlusal device out of the mouth. This problem was resolved in 36 patients after removal of eccentric occlusal interferences. It is suggested that adjunctive teeth-associated signs and symptoms be initially recorded and addressed in patients, especially if extensive or invasive dental therapy is planned. Although this clinical study in a private practice was carefully performed, it does not meet the criteria of evidence-based research, because a control group was not included.     

Epidemiology of signs and symptoms in temporomandibular disorders: clinical signs in cases and controls

An epidemiologic study of clinical signs and symptoms of temporomandibular disorders (TMD) was conducted with a probability sample of adults enrolled in a major health maintenance organization (HMO). This report presents data from a first wave field examination and interview conducted by trained, calibrated dental hygienist field examiners. Significant gender differences for vertical jaw opening measures were observed but no significant age differences were found for the distribution of clinically relevant findings. Clinic cases showed smaller amounts of vertical range of jaw motion but did not differ from community cases or controls on extent of lateral, protrusive, or retrusive mandibular movements; on classification of occlusion; or on dentally related variables. Clinic cases had more pain during all jaw excursions as well as during muscle and joint palpation. Joint clicking sounds were also observed more frequently in clinic cases.     

Ultrasonography of masseter muscle size in normal young adults

summary the present study was planned to determine the relationship between linear dimensions of human masseter muscle cross-section and cross-sectional area (CSA), and to assess symmetry between the two sides in normal young adults. Cross-sectional images of the masseter muscle were measured bilaterally by real-time ultrasound imaging in 39 healthy dentate subjects, 19 males and 20 females, aged 21-47. From stored images, CSA and two linear measurements of muscle cross-section were obtained (the shortest and the longest distance through the muscle group). Correlation and regression analyses were performed to examine the relationship between CSA and the linear dimensions (both individually and with the linear dimensions multiplied). Symmetry of CSA between the two sides of the face was examined using the paired t -test. The significance of correlation coefficients (r) and the difference between the slopes of the regression lines were also examined. Masseter CSA was larger in males than in females. All correlation values between CSA and linear measurements were significant but muscle CSA was most accurately predicted when the linear measurements were multiplied ( r = 0.97; P < lt; 0.001). Although the correlation in this regard was high, the linear dimensions consistently overestimated the actual CSA by approximately 25%. Males showed more symmetry of CSA than females. The range of values for symmetry of masseter CSA was too large to assess abnormal asymmetry in patients with unilateral symptoms.     

The craniofacial morphology and maximum bite force in sleep bruxism patients with signs and symptoms of temporomandibular disorders

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.     

Relationship between the number of occlusal contacts and masticatory muscle activity in healthy young adults

The electromyographic (EMG) potentials of left and right masseter and temporalis anterior muscles were recorded in 23 healthy young adults during: 1. a 3-second maximum voluntary clench (MVC) on cotton rolls positioned on the posterior teeth (standardized recording); and 2. a 3-second MVC in intercuspal position. EMG potentials recorded in intercuspal position were standardized as a percentage of the mean potentials of the standardized recording, and the EMG muscle activity was calculated. The number of occlusal contacts in intercuspal position was assessed by using eight microm thick shim stocks. Two groups of subjects with either 1. Less than ten occlusal contacts (11 subjects with "few contacts"); or 2. At least ten occlusal contacts (12 subjects with "many contacts") were selected. The MVC muscle activity in the "few contacts" group was significantly lower than that recorded in the "many contacts" group (p<0.005). In conclusion, the number of occlusal contacts and masticatory muscular function are significantly related, at least in young adults with a sound stomatognathic apparatus.     

Association between painful temporomandibular disorders and sleep quality: A systematic review

This review aimed to systematically evaluate the association between painful temporomandibular disorders (TMD) and sleep quality in adults. Observational case-control studies using either RDC/TMD or DC/TMD for TMD diagnostic and validated questionnaires for sleep quality were selected by two reviewers in a two-phase process. A systematic review was conducted in accordance with the PRISMA statement. The search was performed in PubMed/MEDLINE, LILACS, SCOPUS, PsycINFO, Web of Science and Grey literature (ProQuest, Google Scholar and OpenGrey). To be eligible, studies had to include adults (>18 years old), with no language, gender or time of publication restrictions. The quality of the papers was assessed using the Newcastle-Ottawa Scale (NOS). Eight case-control studies were included, with high (4) and moderate (4) quality assessment. Seven studies reported a significant association between the presence of painful TMD and sleep quality (P < .05), while the other found impaired sleep in participants with higher sensitivity to heat pain (P < .001). When pain levels were concerned, using different pain scales, six studies found differences when compared to control groups. One study showed that in non-painful TMD, the PSQI values were not different when compared to the control group. An association exists between painful TMD and sleep quality. The presence of pain seems to strongly impact the sleep quality in TMD patients.