Purpose: To investigate the construct validity of perceived tooth grinding for sleep bruxism using the known groups method in patients with temporomandibular disorders (TMD).
Methods: The subjects comprised 148 consecutive outpatients who were diagnosed as having TMD. The subjects underwent multiple patient questionnaires including Symptom Checklist-90-Revised (SCL-90-R) and reported the intensity of their subjective orofacial pain using a visual analogue scale (VAS). Clinical examinations, including muscle palpation, were conducted by two clinicians whose diagnostic reliability had already been verified.
Results: The subjects were classified into bruxer (n=74) and non-bruxer (n=74) groups according to the levels of their perceived tooth grinding during past six months. No significant differences were found between the two groups in age, sex, TMD subgroup distribution, pain intensity (spontaneous pain, pain during jaw movements and headache), intensity and number of locations of muscle tenderness, and intraoral findings (the intensity of attrition, scalloping tongue and cheek biting). A logistic regression analysis using five subscales of SCL-90-R along with sex and age revealed that females (odds ratio=3.15, P=.028) and anxiety (odds ratio=1.06, P=.003) were statistically significant variables for perceived tooth grinding.
Conclusions: The study results suggest that the construct validity of perceived tooth grinding is low as clinical criteria for sleep-related bruxism.

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Objective: We evaluated the morphological change of the condylar head and disc position in teenage patients with temporomandibular disorders who could be followed up.
Materials and Methods: We selected 37 cases (74 joints) in teenagers for whom it was possible to examine the MR image at the initial and follow-up examinations. The follow-up examination was performed one year after the initial examination. We evaluated the MR image findings of the disc position and bone change of the condylar head.
Results: At the initial examination, diagnoses based on MR image were as follows: 8 joints had no displacement of the disc (NDD), 8 joints had sideways disc displacement (SDD), 26 joints had anterior disc displacement with reduction (ADDwR) and 32 joints had anterior disc displacement without reduction (ADDwoR). Fifteen joints (20.7%) showed bone changes, which were as follows: eleven joints had erosion, 1 joint had osteophyte, 2 joint had irregular surface and 1 joint had concavity.
At the follow-up examination, the bone change had disappeared in 2 joints, but there was new bone change of the condylar head in 15 joints. The bone changes were as follows: 12 joints had erosion, 4 joints had osteophyte, 6 joints had flattening and 6 joints had deformity. In total, bone changes were observed in 28 joints (37.8%).
Conclusions: In teenage patients, morphological change of the TMJ may be observed in the short term, so long-term follow-up is necessary.

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Purpose: There has been no report on the chair time for temporomandibular disorders (TMD). The purpose of this study was to survey chair times for splint therapy at university TMD clinics and private dental offices.
Method: A survey on the clinical practice for TMD was conducted for 14 university TMD clinics and 33 private dental offices for two months. At both types of clinic, we investigated the chair time for each TMD patient who was selected for splint therapy, and compared the two groups in terms of the type of splint, the details of the chair time of each practical session (i.e. first visit, examination, insertion of splint, adjustment of splint, observation, consultation and so forth) and each chair time.
Result: There was a significant difference between the mean chair time between the university TMD clinics (hereafter "university group") and the private dental offices (hereafter "dental office group") (p=0.0005). The time for the first visit for the university group was longer than that for the dental office group (p=0.000029). There was no significant difference in the chair time for insertion of splint (p=0.137) and adjustment of it (p=0.482) between both groups.
Conclusion: This study revealed that it took a long time to perform the physical examination for both groups. In addition, 44% of the university group and 22% of the dental office group required over 30 minutes to insert splints. Furthermore, 48% of the university group and 33% of the dental office group required over 20 minutes to adjust splints.

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