Effects of orofacial myofunctional therapy on temporomandibular disorders

The objectives of the current study were to analyze the effects of orofacial myofunctional therapy (OMT) on the treatment of subjects with associated articular and muscular temporomandibular disorders (TMD). Thirty subjects with associated articular and muscular TMD, according to the Research Diagnostic Criteria (RDC/TMD), were randomly divided into groups: 10 were treated with OMT (T group), 10 with an occlusal splint (OS group), and 10 untreated control group with TMD (SC). Ten subjects without TMD represented the asymptomatic group (AC). All subjects had a clinical examination and were interviewed to determine Helkimo's Indexes (Di and Ai), the frequency and severity of signs and symptoms, and orofacial myofunctional evaluation. During the diagnostic phase, there were significant differences between groups T and AC. There were no significant differences between group T and OC and SC groups. During the final phase, groups T and OS presented significant improvement, however, the group T presented better results and differed significantly from group OS regarding the number of subjects classified as Aill; the severity of muscular pain and TMJ pain; the frequency of headache and the muscles and stomatognathic functions. The group T differed significantly from the SC group but no longer differed significantly from the AC group. OMT favored a significant reduction of pain sensitivity to palpation of all muscles studied but not for the TMJs; an increased measure of mandibular range of motion; reduced Helkimo's Di and Ai scores; reduced frequency and severity of signs and symptoms; and increased scores for orofacial myofunctional conditions.     

Temporomandibular disorders in Saudi females seeking orthodontic treatment

The aim of this study was to describe the prevalence of signs and symptoms of temporomandibular disorders (TMD) in a group of patients seeking orthodontic treatment. One hundred and ninety one consecutive prospective orthodontic female patients, divided into three age groups of 8, 14 and 18 years, were examined for TMD signs and symptoms and orthodontic treatment need (IOTN). The percentages of signs and symptoms found were 41 and 30%, respectively. No significant association was found between IOTN and TMD signs and symptoms. The youngest age group reported significantly less headache and temporomandibular joint (TMJ) noise. Headache was significantly associated with all TMD symptoms and with tenderness to palpation. In conclusion, the results indicate that malocclusion could not be considered as a primary aetiologic factor for TMD within the age range studied.     

Anamnestic index severity and signs and symptoms of TMD

The aim of this study was to determine the frequency and to characterize the symptoms and clinical signs of temporomandibular disorders (TMD) related to each severity category of Fonseca's anamnestic index in a sample of Brazilian young adults (mean age 21.61+/-1.91 years, 87% females and 13% males), by the application of an anamnestic index proposed by Fonseca (1992) and by clinical examination considering mandibular range of motion and tenderness to palpation of stomatognathic system structures. A significant number of participants were classified with mild TMD (43.2%) and moderate TMD (34.8%). Pain frequency during mastication, temporomandibular joint (TMJ) pain, and TMJ sounds were shown to be good predictors of TMD severity. Neck pain, headache, difficulty during mouth opening and lateral deviation, and tenderness to palpation of masticatory sites and during protrusion accompanied the TMD severity but failed to demonstrate differences between moderate and severe groups, showing a poor ability to determine TMD severity progression. This study suggests that not only the frequency of signs and symptoms of TMD should be determined, but also symptom severity and its relationship to the presence of clinical signs in order to discriminate patients with real treatment needs in nonpatient samples.     

Temporomandibular disorders in 19-year-old Korean men.

PURPOSE: The purpose of this study was to determine the prevalence and the nature of the relationships between 3 temporomandibular joint disease (TMD) symptoms and symptoms of associated structures. MATERIALS AND METHODS: This study was designed to rule out the effect from the uneven composition of the samples on TMD symptoms. The samples were collected from subjects who were of the same age, gender, district, and race. Nineteen-year old men (n = 27,978) were selected and investigated by means of questionnaires and clinical examinations. The prevalence of each symptom was studied and tried to determine the effects of the TMD-associated signs on the TMD signs. The indices allocated to reflect the TMD signs and symptoms and the others were dichotomized for bivariate analysis. The predictor variables were headache, neck pain, referred pain, stress, past trauma history in the TMJ, past TMJ dislocation, bruxism, and clenching. The outcome variables were mouth opening limitation, TMJ pain on rest, and TMJ pain during function. RESULTS: The incidence of masticatory muscle stiffness was 17.8%; TMJ sounds, 14.3%; headache, 7.2%; neck pain, 13.5%; bruxism, 8.4%; and clenching, 9.9%. Stress occurred in 12.8%, past trauma history in 11%, and previous joint dislocation in 2.5%. The experience of dislocation in the TMJ was found to be the most important risk factor in terms of mouth opening limitation (odds ratio, 4.08, P <.0001), joint pain during function (odds ratio, 5.50, P <.0001), and joint pain in the rest state (odds ratio, 4.63, P <.0001). Referred pain and the experience of trauma in TMJ were the secondary risk factors in terms of joint pain and referred pain and the stress in terms of mouth opening limitation. Considering referred pain can be induced by TMD, stress may be more related to mouth opening limitation (odds ratio, 2.18, P <.0001), and the experience of trauma in TMJ may be more related to pain in the rest state (odds ratio, 2.56, P <.0001) and during function (odds ratio, 2.47, P <.0001). CONCLUSIONS: The prevalence of TMD signs and symptoms as determined by this examination was in accord with the findings in women or mixed samples of other workers. Prior experience of a dislocated disc was found to be the most risky factor in TMD. Stress was related to limitations of mouth opening, and the experience of trauma in the TMJ was found to be related to pain in the joint region. Bruxism may not be a direct risk factor in TMD, and the clenching habit found to be more harmful than bruxism.     

Anamnestic Index Severity and Signs and Symptoms of TMD

Abstract

The aim of this study was to determine the frequency and to characterize the symptoms and clinical signs of temporomandibular disorders (TMD) related to each severity category of Fonseca’s anamnestic index in a sample of Brazilian young adults (mean age 21.61±1.91 years, 87% females and 13% males), by the application of an anamnestic index proposed by Fonseca (1992) and by clinical examination considering mandibular range of motion and tenderness to palpation of stomatognathic system structures. A significant number of participants were classified with mild TMD (43.2%) and moderate TMD (34.8%). Pain frequency during mastication, temporomandibular joint (TMJ) pain, and TMJ sounds were shown to be good predictors of TMD severity. Neck pain, headache, difficulty during mouth opening and lateral deviation, and tenderness to palpation of masticatory sites and during protrusion accompanied the TMD severity but failed to demonstrate differences between moderate and severe groups, showing a poor ability to determine TMD severity progression. This study suggests that not only the frequency of signs and symptoms of TMD should be determined, but also symptom severity and its relationship to the presence of clinical signs in order to discriminate patients with real treatment needs in nonpatient samples.     

Prevalence of signs and symptoms of temporomandibular disorders in an urban and rural German population: results of a population-based Study of Health in Pomerania.

OBJECTIVE: Based on a randomized, population study (Study of Health in Pomerania [SHIP]), the objective of the present study was to determine incidence of signs and symptoms of temporomandibular disorders (TMD) in adults 20 years or older and to compare the data with TMD prevalence of other exclusively random sample studies that fulfilled criteria similar to those of this study (age > or = 20 years, age range > or = 40 years, sample size > or = 500 subjects, equal gender distribution). METHOD AND MATERIALS: Men and women (n = 7,008) 20 to 79 years of age from mid- and small-sized towns in a rural region in northeast Germany were randomly sampled from resident registry office files. The response rate was 68.8%. Adults between the ages of 20 and 81 years (n = 4,289) were clinically and anamnestically examined. RESULTS: Half of the subjects (49.9%) had one or more clinical signs of TMD, but only 2.7% were subjectively aware of temporomandibular joint (TMJ) pain symptoms. Women showed higher frequency for all signs and symptoms of TMD than men. However, these differences were not significant for all signs and symptoms in all age groups. The influence of age on TMD signs and symptoms was less pronounced. The prevalence for the following variables found in the present study compared to those of other comparable, random sample studies was: clinical examination; (TMJ) tenderness to palpation (5% versus 2% to 6%); masticatory muscle tenderness (15% versus 19% to 21%); joint sounds (25% versus 15% to 25%); limited maximum mouth opening < 40 mm (9% versus 5% to 8%); pain upon movement of the mandible (1% versus 1% to 3%); irregular jaw movements (deviation, deflection) (28% versus 28%); interview: subjective joint sounds (9% versus 11% to 13%); and subjective TMJ pain (3% versus 4% to 7%). CONCLUSION: The TMD incidence in the current study agreed quite well with the other studies based on random samples with similar subjects and design. The large range of prevalence for signs and symptoms of TMD documented in reviews and meta-analyses could therefore not be confirmed.     

Symptoms and signs of temporomandibular disorders and oral parafunctions among Saudi children

This study aimed to record the prevalence of signs and symptoms of temporomandibular disorders (TMD) and oral parafunctions among Saudi children. A questionnaire and a clinical examination of signs and symptoms of TMD were performed on 1940 stratified randomly selected schoolchildren. The sample was divided into three groups, 505 with primary, 737 with mixed and 734 with permanent dentition. The prevalence of TMD signs was found to be 20.7% and the most common sign of TMD was joint sounds (11.8%). The second most common sign was restricted mouth opening (5.3%). Muscle and temporomandibular joint (TMJ) pain as well as deviation upon jaw opening appeared infrequently. TMJ sounds were significantly increasing with age (P < 0.05). TMD symptoms as reported by the parents were evident in 24.2% of the returned questionnaires (1113). The most common symptoms were headache (13.6%) and pain on chewing (11.1%). The incidence of headache was found to be significantly increasing from primary to permanent dentition (P < 0.01). No sex difference in the prevalence of any symptom was reported. Nail biting was the most common oral parafunction (27.7%) while bruxism was the least common (8.4%). All parafunctions except bruxism were significantly related to age. Cheek biting and thumb sucking were reported more in females than in males. The importance of a screening examination for symptoms and signs of TMD should not be overlooked in the clinical assessment of the pediatric patient.     

The relationship between headache and symptoms of temporomandibular disorder in the general population

OBJECTIVES: To describe the relationship between headache and symptoms of temporomandibular disorder (TMD) in a general population, and to assess whether there are specific symptoms associated with headache. METHODS: A personal interview survey conducted in 1995 on 483 adult subjects from the metropolitan community of Segrate, northern Italy. RESULTS: The overall prevalence of headache in the past year was 21.2%. The prevalence of temporomandibular symptoms was 54.3%. Headache occurred significantly more in females than males (26.5 vs 15.4%), and in subjects with, rather than without, symptoms of TMD (27.4 vs 15.2%). Among symptoms, temporomandibular pain, temporomandibular joint sounds, and pain on movements of the jaw were associated with headache using a univariate analysis. After adjustment for confounding variables, a multiple logistic regression confirmed a significant relationship of headache with temporomandibular pain (OR 1.83, 95% CI, 1.07-3.15). CONCLUSIONS: In the general adult population there is an association between headache and symptoms of TMD. A functional evaluation of the stomatognathic system should be therefore considered in subjects with unexplained headache, even if chronic conditions and mechanical symptoms of temporomandibular disorder are absent.     

Mood spectrum in patients with different painful temporomandibular disorders

The purpose of this study was to investigate for difference in the prevalence of mood disorders between patients with different painful temporomandibular disorders (TMD). After a sample size necessary for the study was calculated, 60 patients with a painful TMD were selected and divided into the following groups: myofascial pain (n=20), temporomandibular joint (TMJ) pain (n=18), combined myofascial and TMJ pain (n=22). Two distinct comparison groups were selected: subjects with a nonpainful TMD (n=25) and TMD-free subjects (n=29). All participants filled out a self-report validated instrument (MOODS-SR) to evaluate psychopathological symptoms related to mood disturbances. A one-way analysis of variance (ANOVA) with Bonferroni's post hoc test for multiple comparisons was performed to investigate for significant differences among the groups. The three groups of patients with painful TMD scored significantly higher than comparison groups in all MOODS-SR domains investigating depression, but no difference was shown between subjects with myofascial pain and those with TMJ pain. No significant differences among the groups emerged for the presence of manic symptoms, indicating that depressive disorders associated with TMD are not an expression of a more complex manic depressive illness. The study concluded that the presence of depressive symptoms in TMD patients seems to be related to the presence of a painful condition and seems to be unrelated to the location of pain. Furthermore, depressive disturbances in painful TMD patients affect the whole spectrum of depressive psychopathology.     

The craniocervical connection: a retrospective analysis of 300 whiplash patients with cervical and temporomandibular disorders

Because the concept of whiplash as a causative factor for temporomandibular disorders (TMD) is highly controversial, we decided to do a retrospective analysis of patients treated in our office who had sustained whiplash injuries and were treated for cervical and temporomandibular disorders. The records of 300 patients with TMD preceded by a motor vehicle accident were examined retrospectively. The most common presenting symptoms, in order, were: jaw pain, neck pain, post-traumatic headache, jaw fatigue, and severe temporomandibular joint (TMJ) clicking. The most common TMD diagnoses were: masseter trigger points, closing jaw muscle hyperactivity, TMJ synovitis, opening jaw muscle hyperactivity, and advanced TMJ disk derangement. Based primarily on the physical examination, we concluded that the TMJ and surrounding musculature should be examined similarly to other joints, with no preconceived notion that TMD pathology after whiplash is unlikely.     

Generalized joint hypermobility and temporomandibular disorders: inherited connective tissue disease as a model with maximum expression

AIMS: To study the relationship between generalized joint hypermobility (GJH) and temporomandibular disorders (TMD) by assessing prevalence and patient characteristics of TMD in a population of patients with maximum expression of GJH as a symptom of inherited connective tissue disease. In addition, diagnostic reliability of a series of clinical signs indicative of temporomandibular joint (TMJ) hypermobility was tested. METHODS: The study sample consisted of 42 subjects with GJH, 24 with Marfan syndrome and 18 with Ehlers-Danlos syndrome. A subgroup of 27 individuals was selected by age (> or = 18 yrs) and was compared to 40 controls with TMD and normal peripheral joint mobility. TMD diagnoses were assigned to each subject according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). RESULTS: In the GJH sample (n = 42), 71.4% of the subjects were symptomatic for TMD. Of those, 13.3% had sought treatment. A myofascial pain diagnosis was made in 69%, disc dislocation with reduction was diagnosed in 85.7%, and TMJ arthralgia in 61.9%. Multiple TMD diagnoses were assigned in 69% of the subjects; of these, 57% had 3 or more subgroup diagnoses. Joint noises (P < .01) and recurrent TMJ dislocations (P < .01) were a frequent finding in adult GJH subjects (n = 27) compared to controls, with symptomatic GJH subjects presenting more and more prolonged dislocation events than asymptomatic subjects (P < .001). TMJ hypermobility signs were expressed significantly more often in GJH compared to controls with TMD and normal joint mobility. CONCLUSION: This study indicates a positive relationship between GJH and TMD.     

Risk factors for headache, including TMD signs and symptoms, and their impact on quality of life. Results of the Study of Health in Pomerania (SHIP).

OBJECTIVE: The aim of this investigation was to evaluate the role of various signs and symptoms of temporomandibular disorders (TMD), among other potential risk factors, in developing frequent headache in a population-based sample of the cross-sectional epidemiologic Study of Health in Pomerania (SHIP). The impact of headache and of myogenous and arthrogenous signs of TMD on the quality of life of this sample was evaluated. METHOD AND MATERIALS: Medical history and dental and sociodemographic parameters of 4,255 subjects were checked for correlations with frequent headache using a multivariate logistic regression model. The quality of life of the headache sufferers was evaluated with a questionnaire on mental and physical health. RESULTS: Of the sample, 9% reported suffering from frequent headache. Significant values for the odds ratios for the whole sample were found for pain on palpation of the masticatory muscles; the anamnestic question on masticatory muscle pain; ear noises; lateral palpation pain of the temporomandibular joints (TMJ); several sleep disorders; psychosomatic complaints; and risk for women. Palpation pain of the muscles showed a dose/response effect. Subjects with a higher education level had a significantly reduced risk for developing frequent headache. Anamnestic questions for pain in the TMJ area, TMJ clicking, smoking, alcohol abuse, contraceptives, income, and chronic diseases did not correlate significantly with frequent headache. Subjects who reported frequent headache exhibited a significant reduction of physical and mental health scores. Pain upon muscle palpation showed significantly reduced scores on both scales for both genders. CONCLUSION: Within the limitations of this study, in addition to sensitive TMJs, mainly palpation-sensitive masticatory muscles showed a significant relation to the occurrence of frequent headache. Because of the number of tested covariates originally included in the model, this relation seems essential.     

Symptoms and signs of temporomandibular disorders before, during and after orthodontic treatment

The relationship between orthodontic treatment and symptoms and signs of temporomandibular disorders (TMD) was studied prospectively and longitudinally in 65 adolescent girls with Class II malocclusion. The subjects received orthodontic fixed appliance treatment with the straight-wire technique combined with or without extractions and were examined for symptoms and signs of TMD before, during, after, and finally one year post-treatment. Both symptoms and signs of TMD showed considerable fluctuations over the three-year period within the individuals. The general tendency was a decreased prevalence of symptoms of TMD over the three years. The prevalence of pain on mandibular movement and tenderness to palpation of the masticatory muscles was significantly less common during and after orthodontic treatment than before. Clinically registered TMJ clicking increased slightly over the three year period. One orthodontic treatment effect when normalizing Class II malocclusions with fixed appliances was a decreased prevalence of functional occlusal interferences. We concluded that the orthodontic treatment either with or without tooth extractions did not increase the risk for TMD or worsen pre-treatment signs of TMD. Subjects with Class II malocclusion and pre-treatment signs of TMD of muscular origin seemed rather to benefit functionally from orthodontic treatment in a three-year perspective.     

Temporomandibular disorders and headache

Headache is a common symptom, but when severe, it may be extremely disabling. It is assumed that patients who present to dentists with headache often are diagnosed with a temporomandibular disorder (TMD), although many may have migraine. TMD as a collective term may include several clinical entities, including myogenous and arthrogenous components. Because headache and TMD are so common they may be integrated or separate entities. Nevertheless, the temporomandibular joint (TMJ) and associated orofacial structures should be considered as triggering or perpetuating factors for migraine. This article discusses the relationship between the TMJ, muscles, or other orofacial structures and headache.     

Temporomandibular disorders in the active phase of orthodontic treatment

summary Subjective symptoms and clinical signs of temporomandibular disorders (TMD) as well as presence of headache, bruxism and occlusal interferences were examined in 50 patients (mean age 12.9 years) before, during and immediately after orthodontic treatment. The prevalences of signs and symptoms of TMD were high before the treatment in comparison with subjects in an epidemiological study. Except for TMJ sounds, signs and symptoms of TMD as well as presence of headache decreased during the treatment. The major factor for decrease of the dysfunction index during the treatment compared with before the treatment, was tenderness to palpation of the masticatory muscles. Although there was a high prevalence of occlusal interferences during treatment, they seemed to have little importance for development of TMD. One explanation may be that the orthodontically moved teeth are sensitive to contact resulting in a decrease of oral parafunctions. Such a decrease was also reported by the patients.     

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.     

Evaluation of minimum interdental threshold ability in dentate female temporomandibular disorder patients

Summary Minimum interdental threshold is the smallest thickness that can be detected between teeth during an occlusion and has an influence on the occlusal force and on the control of mandibular movements. The aim of this study was to assess the possible association of the signs and symptoms of temporomandibular disorders (TMD) with the ability to detect a minimum interdental threshold. Two hundred women were equally divided into four groups: asymptomatic (control), subjects with masticatory muscle pain, with articular [temporomandibular joint (TMJ)] pain and mixed (muscular and articular pain). Evaluation of the ability to detect a minimum interdental threshold was performed using aluminium foils with 0·010, 0·024, 0·030, 0·050, 0·080 and 0·094 mm of thickness in the premolar region. A total of 20 tests with each thickness for each patient were performed, starting with the thickest foil (0·094 mm) and ending with the thinnest one. The myogenic pain and articular groups presented significantly higher threshold values (0·020 and 0·022 mm, respectively), when compared to the control. Both groups reached the level of certain perceptiveness only at 0·030 mm. No significant correlation was found between minimum interdental threshold and age. These results suggest that discrimination of thicknesses can be disturbed as a consequence of TMD manifestations and not the cause of it. Clinicians should, therefore, be aware that changes on muscles and TMJ can secondarily lead to occlusion changes. The mechanisms involved in this process, however, are not well understood and warrant further investigation.     

Signs and symptoms of temporomandibular disorders in Nigerian adult patients with and without occlusal tooth wear

OBJECTIVES: The purpose of this study was to investigate the prevalence of signs and symptoms of temporomandibular disorders in Nigerian patients with and without occlusal tooth wear, and to relate the signs and symptoms with the severity of occlusal tooth wear. METHODS: One hundred and fifty patients with occlusal tooth wear, and 100 control subjects participated in this study (mean age 40.8 +/- 12.2 years, range 18-65 years). Exclusion criteria included patients and subjects with more than one missing opposing pair of premolars or molars, restorations covering the entire incisal edge, canine cusps and occlusal surfaces of premolars and molars. The severity of occlusal wear was assessed using the tooth wear index (TWI) designed by Smith and Knight (1984). Chi-square test was used to compare the differences in signs and symptoms of TMD. P < 0.05 was defined as significant. RESULTS: Although more females reported pain than males the difference was not statistically significant (p = 0.05). Except for impaired range of movement, tooth wear patients and controls differ significantly with respect to the variables; pain report, pain on palpation, TMJ sound and deviation on opening (p < 0.001). Patients with mean occlusal TWI score of > or =3 differ significantly from those with TWI score < or =2 with respect to pain on palpation and TMJ sound (p < 0.001). CONCLUSIONS: Posterior occlusal wear (mean TWI scores of 3 or 4) was significantly associated with pain on palpation and TMJ sound. Hence there may be a clinically relevant risk of TMD among Nigerian patients with occlusal tooth wear.     

Signs and symptoms of temporomandibular disorders and the incidence of tinnitus

In a cross-sectional analysis of data from the Study of Health in Pomerania (SHIP 0), temporomandibular disorders (TMD) were the strongest predictors for tinnitus beside headache. The aim of this study was to investigate whether signs and symptoms of TMD can be identified as risk factors for developing tinnitus. The SHIP 1 is a population-based 5-year longitudinal study intended to systematically describe the prevalence of and risk factors for diseases common in the population of Pomerania in northern Germany. A total of 3300 subjects (76% response) were reevaluated after 5 years for tinnitus and signs and symptoms of TMD using the same questionnaires and examination tools as baseline. To estimate the relative risk (RR) appropriately, a modified Poisson regression was used. After exclusion of prevalent cases with diagnosed tinnitus, 3134 subjects were analysed. Among the 191 exposed subjects with palpation pain in the temporomandibular joint (TMJ), 24 subjects (12·6%) received diagnosed tinnitus after 5 years, whereas among the 2643 unexposed subjects 142 subjects (5·8%) received tinnitus yielding a risk difference of 7·7% (95% confidence interval [CI]: 3·0%-12·5%) and a risk ratio of 2·60 (95% CI: 1·7-3·9). The risk ratio was 2·4 (95% CI: 1·6-3·7) after adjustment for gender, age, school education and frequent headache. Pain on palpation of the TMJ, however, did not worsen the prognosis for tinnitus in prevalent tinnitus cases (RR = 0·8, P = 0·288). Signs of TMD are a risk factor for the development of tinnitus.     

Oral parafunctions and association with symptoms of temporomandibular disorders in Japanese university students

We examined whether oral parafunctions are associated with symptoms of temporomandibular disorders (TMD) in 3557 Japanese university students, aged between 18 and 26 years. Participants completed a questionnaire regarding various oral parafunctions and subjective symptoms related to TMD, and underwent a dental examination. The prevalence of temporomandibular joint (TMJ) noise, TMJ pain and impaired mouth opening was 41.7, 16.0 and 16.3%, respectively. The most prevalent parafunction was sleeping on one side (60.2%), followed by supporting the jaw by leaning on the palm of the hand (44.8%). Mean age, decayed, missing and filled teeth, and number of teeth were not significantly different between TMD positive and negative groups according to unpaired t-test. The chi-squared test revealed that the ratio of females was significantly higher among students with TMD than without TMD. Multiple logistic regression models adjusted for age and gender demonstrated that chewing on one side caused an increased risk of TMJ noise [odds ratio (OR) = 1.52, P < 0.001], TMJ pain (OR = 1.54, P < 0.001), and impaired mouth opening (OR = 2.00, P < 0.001). Tooth clenching also increased the risk of TMJ noise (OR = 1.86, P < 0.001), TMJ pain (OR = 1.79, P = 0.001) and impaired mouth opening (OR = 1.88, P < 0.001). Further prospective cohort studies, including other potential risk factors, are required to clarify these relationships.