Comparison of occlusal discomfort in patients with temporomandibular disorders between myofascial pain and disc displacement.

We compared occlusal discomfort in patients with temporomandibular disorders (TMD) between myofascial pain (MFP) and disc displacement (DD) using a database created from Sep, 2003 to Aug, 2005. We selected 71 patients with MFP and 170 patients with DD to construct a null model of structural equation modeling (SEM) in which anxiety influenced depressive mood, depressive mood aggravated occlusal discomfort and sleep complaints, and sleep complaints or an onset event caused by another person aggravated occlusal discomfort. We performed a simultaneous analysis of patients with MFP and DD. The estimated parameter of the path from depressive mood to occlusal discomfort was significant for patients with MFP, but not for patients with DD. The path from an onset event caused by another person, such as dental treatment to occlusal discomfort was significant in patients with MFP and those with DD. The Goodness of Fit Index (=0.909), The Adjusted Goodness of Fit Index (=0.867), and The Root Mean Square Error of Approximation (=0.039) indicated good acceptability. These results suggested that an increase in depressive mood may aggravate occlusal discomfort in patients with MFP, and an onset event caused by another person, such as dental treatment, also may aggravate occlusal discomfort in patients with MFP and those with DD.

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.

Teeth contacting habit as a contributing factor to chronic pain in patients with temporomandibular disorders.

Many different factors are known to cause and perpetuate the symptoms of temporomandibular disorders (TMD). However, the roles of parafunctional factors have not been clearly elucidated. We found one of these habits in the clinical setting. This parafunctional habit involves daily light touching of the upper and lower teeth, when the mouth is closed. We named this habit Teeth Contacting Habit (TCH). [OBJECTIVES] To investigate the following hypotheses: 1) TCH is associated with perpetuation of chronic pain of TMD patients; 2) TCH is associated with other behavioral factors. [METHODS] Two hundred and twenty-nine TMD outpatients with chronic pain were analyzed with multivariate logistic regression models. [RESULTS] TCH was found in 52.4% of patients. Patients with TCH and pain lasting for more than four months were less likely to experience improvements in pain at the first visit (OR = 1.944, p = 0.043). Other factors associated with TCH were as follows: unilateral chewing (OR = 2.802) and involvement in a precision job (OR = 2.195). [CONCLUSION] TCH can prolong TMD pain and is associated with other behavioral factors.

Difficulty of food intake in patients with temporomandibular disorders.

PURPOSE: Although patients with temporomandibular disorders (TMD) often report impaired eating, the features of food intake difficulty have rarely been estimated. This study compared subjective difficulty in 4 categories of food intake situations among 3 subgroups of TMD patients. MATERIALS AND METHODS: A total of 511 TMD patients (402 women, 109 men, mean age 36.4 +/- 15.4, range 12 to 82) participated in this study. Subjects were divided into 3 TMD subgroups: myofascial pain (MFP), disc displacement with/without reduction (DD), and arthralgia or osteoarthritis (Arth). Patients' level of food intake difficulty was assessed using a visual analogue scale (VAS) for 4 categories of food intake situations: difficulty in putting food into mouth (PUT), difficulty in biting off foods (BIT), difficulty in grinding down foods (GRD), and overall difficulty in consuming a meal (OAL). RESULTS: Nearly all patients (98.6%) exhibited food intake difficulty in at least 1 category. In the category of PUT, the DD group exhibited significantly more difficulty than the MFP and Arth groups (P < .048), and the Arth group had a higher VAS score than the MFP group (P = .030). With regard to BIT and GRD, there was no significant difference among the TMD subgroups. In OAL, the DD group showed more difficulty than the MFP group (P = .046). CONCLUSION: TMD patients experienced impaired food intake ability. In particular, the DD group experienced more difficulty than the MFP group. Concerns about types of food and food intake behavior for each TMD subtype should be taken into account in the management of TMD patients.

Development of a new questionnaire to assess pain-related limitations of daily functions in Japanese patients with temporomandibular disorders.

BACKGROUND: Various measures/scales have been used to assess oral health-related quality of life in patients with temporomandibular disorders (TMDs). However, there have been few reports on the validity of questionnaires, and even fewer assessments of their use in Japanese sociocultural conditions. OBJECTIVES: The objectives of the study were: (i) to develop and refine the number of questions concerning pain-related limitations of daily function in the TMD questionnaire (LDF-TMDQ, 13 items) in Japanese patients with TMD, (ii) to assess factor validity, and (iii) to determine convergent and discriminant validity of the LDF-TMDQ with the observed items within a multidimensional questionnaire. METHODS: Four hundred and fifty-six (85.9%) outpatients with TMD were enrolled. The subjects were allocated into two roughly equal groups--E-group (233) for exploratory factor analysis and C-group (223) for confirmatory factor analysis [structural equation modeling (SEM)]. RESULTS: The exploratory factor analysis extracted 10 items and three factors. SEM showed the revised model to accurately describe the relationships between the measured items. As to convergent validity, the factor 'limitation in executing a certain task' and 'limitation of mouth opening' showed significant correlations with the observed items within the multi-dimensional questionnaire. However, the factor 'limitation of sleeping', show no correlation with any item. As to discriminant validity, all three factors had correlation coefficients below 0.4 with the psychological scale, the personality scale, and the visual analog scale for pain intensity. CONCLUSION: The LDF-TMDQ was reduced from 13 items to 10. The factor validity of the LDF-TMDQ, and the construct validity of 'limitation in executing a certain task' and 'limitation of mouth opening' were confirmed, while that of 'limitation of sleeping' remains to be determined.

[Sensory perceptive and discriminative abilities of patients with occlusal dysesthesia].

PURPOSE: It is not rare for dentists to come across patients who complain of several uncomfortable feelings of occlusion despite the absence of any observable occlusal anomaly or discrepancy. These kinds of symptoms are well defined by the term "occlusal dysesthesia" (OD). This study evaluated the occlusal perceptive and discriminative abilities in OD patients. METHODS: The sensory perceptive and discriminative abilities were tested in 8 OD patients and 31 healthy subjects as controls. All of these subjects went through three types of tests: 1) thickness discrimination test by using occlusal registration foils, 2) thickness discrimination test by using bite block, and 3) mouth opening reproducibility test. RESULTS: The median of the foil thickness discrimination ability of the control group was 14 microm and that of the patient group was 8 microm. In the bite block thickness discrimination test, both groups showed less than +/- 1mm thickness discrimination ability on average and were able to reproduce pre-indicated mouth opening with less than 10% error. There was no significant difference in these study results between the two groups. CONCLUSIONS: Sensory perceptive and discriminative abilities of OD patients were not significantly different from those of the healthy subjects in this study sample.

Association between masseter muscle activity levels recorded during sleep and signs and symptoms of temporomandibular disorders in healthy young adults.

AIMS: To examine whether any signs and symptoms of temporomandibular disorders were significantly associated with masseter muscle activity levels during sleep. METHODS: One hundred three healthy adult subjects (age range, 22 to 32 years) participated in the study. They were asked to fill out questionnaires, undergo a calibrated clinical examination of their jaws and teeth, and perform 6 consecutive nightly masseter electromyographic (EMG) recordings with a portable EMG recording system in their home. The EMG data were considered dependent variables, while the questionnaire and examination data were considered independent variables. Multiple stepwise linear regression analysis was utilized to assess possible associations between these variables. RESULTS: Both gender and joint sound scores were significantly related to the duration of EMG activity. None of the other independent variables were found to be related to any of the muscle activity variables. CONCLUSION: The results suggest that both gender and clicking are significantly related to duration of masseter EMG activity during sleep.

Accuracy and precision of a system for assessing severity of tooth wear.

PURPOSE: The purpose of this study was to introduce a computer-assisted quantitative tooth wear-analyzing system and test its accuracy and precision. MATERIALS AND METHODS: An image of a horizontally projected dental arch was captured, and the facet area of each tooth was calculated using a digital image analyzer. For normalization, the facet area of the individual tooth was divided by the total area of the corresponding tooth; this result was the tooth wear score. The accuracy and precision of this method were determined through the intraclass correlation coefficient using 10 dental casts. Tooth wear on the dental casts of 50 subjects was actually measured. RESULTS: The accuracy of the tooth wear score determined by a newly trained examiner was greater than 0.85 of the intraclass correlation coefficient; this was tested against the score determined by consensus of three experienced examiners. The reproducibility within a 1-week interval was also greater than 0.85. With regard to the tooth wear score from 50 sets of dental casts, the distribution of tooth wear was generally consistent with data reported in the literature. CONCLUSION: The results suggest that the newly trained examiner can exhibit adequate accuracy and precision after appropriate training in identifying tooth wear facets. Recorded data from 50 subjects added face validity to this new system.

Does tooth wear status predict ongoing sleep bruxism in 30-year-old Japanese subjects?

PURPOSE: This study investigated whether tooth wear status can predict bruxism level. MATERIALS AND METHODS: Sixteen Japanese subjects (eight bruxers and eight age- and gender-matched controls; mean age 30 years) participated in this study. From dental casts of these subjects, the tooth wear was scored by Murphy's method. Bruxism level in these subjects was also recorded for 5 consecutive nights in the subject's home environment using a force-based bruxism detecting system. The relationship between the tooth wear score and bruxism data was evaluated statistically. RESULTS: Correlation analysis between the Murphy's scores of maxillary and mandibular dental arch and bruxism event duration score revealed no significant relationship between tooth wear and current bruxism. CONCLUSION: Tooth wear status is not predictive of ongoing bruxism level as measured by the force-based bruxism detection system in 30-year-old Japanese subjects.

[Postoperative evaluation of surgically treated cases with temporary silicone implant in temporomandibular joint].

We have carried out temporary silicone implants after diskectomies or arthroplasties in temporomandibular joint surgeries to avoid postoperative adhesion and to maintain articular space. We evaluated 19 joints in 15 patients who had received dacron-reinforced silicone implant after silicone sheet removal through follow-up for at least 6 months. The cases included temporomandibular joint disorder (10 joints in 9 patients), psoriatic arthritis (2 joints in 1 patient), ankylosis (4 joints in 3 patients) and synovial chondromatosis (2 joints in 2 patients). On the basis of the criteria of temporomandibular dysfunction for the results, they were classified as bad (4 patients). It is thought that factors other than the implant are related to the bad results in the postoperative evaluation. In this study, lymphadenopathy induced by exfoliated silicone debris could not be confirmed. The temporary silicone implant in the temporomandibular joint was thought to be useful.

Utility and validity of a new EMG-based bruxism detection system.

PURPOSE: The aim of this study was to test the utility and validity of a newly developed EMG-based bruxism recording system, which allowed high-resolution digital recordings of the masseter EMG in the patient's home environment and systematic discrimination of artifact signals with the aid of semiautomated software. MATERIALS AND METHODS: First, simulated bruxism and nonbruxism signals were recorded in two subjects; a total of 72 signals were obtained. Two independent scorers were shown these signals and asked to differentiate bruxism from nonbruxism signals. Second, EMG recordings were actually performed in 56 subjects for six consecutive nights. Using 10 randomly selected recordings, data cleaning was performed by the two scorers to remove any EMG artifact signals, and five bruxism event outcome variables (duration per event, hour, and night, and number per hour and night) were obtained twice with a 7-day interval. RESULTS: The signal differentiation test using signals recorded during simulated tasks revealed that 97% of simulated bruxism and 87% of nonbruxism signals were recognized accurately by the scorers. A total of 317 night recordings, 94% of the scheduled recording nights, were successfully completed by 56 subjects without any substantial difficulty. The results of analysis of intraclass correlation coefficient of outcome variables scored by the two scorers revealed that intrascorer reproducibility varied between .70 and .97. The intraclass correlation coefficients for interscorer reliability were > or = .84. CONCLUSION: This EMG-based bruxism recording system has high utility and reasonable accuracy and precision.