Abnormal static and dynamic brain function in patients with temporomandibular disorders: a resting-state functional magnetic resonance imaging study.

OBJECTIVES: This study was conducted to investigate the brain function of patients with temporomandibular disorders (TMD) by combining the static and dynamic amplitudes of low-frequency fluctuation (ALFF). METHODS: Thirty patients with TMD and 20 healthy controls were enrolled. All the participants completed their questionnaires, received clinical examinations, and underwent resting-state functional magnetic resonance imaging scanning. We compared the static and dynamic ALFF between the patients and healthy controls by conducting a two-sample t-test with AlphaSim correction for multiple comparisons. The correlation between the static and dynamic ALFF of the brain regions with significant group differences and clinical measurements was analyzed. RESULTS: The patients with TMD showed increased static and dynamic ALFF in the posterior cingulate cortex compared with that of the controls (whole-brain level, uncorrected P=0.005; region of interest level with AlphaSim correction, voxel level P<0.005, cluster level P<0.05). The dynamic ALFF of the posterior cingulate cortex was negatively correlated with bilateral condylar vertical discrepancies. The dynamic ALFF in the medial orbitofrontal cortex of the patients with TMD was greater than that of the controls (whole-brain level AlphaSim correction, voxel level P<0.005, cluster level P<0.05). CONCLUSIONS: Our findings revealed that the resting-state brain function of the posterior cingulate cortex and the medial orbitofrontal cortex of patient with TMD increased. These changes probably indicated the potential central mechanisms underlying the increased self-relevant thoughts, negative emotion, and abnormal emotion regulation in TMD.

The impact of media converge on complex networks on disease transmission.

In this paper, we propose an epidemic disease model about the effect of media coverage on complex networks, where the contacts between nodes are treated as a social network. We calculate the basic reproduction number R0 and get that the disease-free equilibrium is locally and globally asymptotically stable if R0< 1, otherwise disease-free equilibrium is unstable and there exists a unique endemic equilibrium, and the disease is permanent. And two immunization strategies are considered: proportional and target immunization. By comparing two immunization strategies, it is found that the target immunization is better than the proportional immunization. Finally, numerical simulations verify our results and some discussions of vaccination strategies are done in the control of infectious dseases.

[The centric relation-maximum intercuspation discrepancy in adult angle's class II pretreatment patients].

OBJECTIVE: This study investigates the differences in condylar position between centric relation (CR) and maximum intercuspation (MI) in Angle's Class II orthodontic patients before treatment. METHODS: 80 cases, who were Angle's Class II pretreatment patients, and 50 cases, who were normal(ideal) occlusion were accepted. Dental casts were mounted on Panadent articulator with CR bite record, taken by bilateral manipulation and load testing. The differences in condylar position between CR and MI in all three spatial planes were measured using the Panadent condylar position indication (CPI). RESULTS: (1) The positive rate of CR-MI discrepancy was 92.50%(74 cases) in the group of Angle's Class II malocclusion and 10.00% (5 cases) in the group of normal occlusion(P< 0.001). 2)74.32% (55 cases) CR-MI discrepancy in 74 cases in the group of Angle's Class II pretreatment patients were coincidence discrepancy. (3)91.25% patients in the group of Angle's Class 11 malocclusion and 66.00% in the group of normal occlusion present occlusion interferences which located at the posterior teeth. CONCLUSION: The results suggested that orthodontists should be aware of a high incidence of condylar displacement in Angle's Class ii pretreatment patients, and measure condylar displacement before the start of comprehensive orthodontic treatment to unmask real jaw relationships and avoid possible misdiagnoses.

Correlation between centric relation–maximum intercuspation discrepancy and temporomandibular joint dysfunction.

OBJECTIVE: To investigate the relationship between centric relation-maximum intercuspation (CR-MI) discrepancy and temporomandibular joint dysfunction (TMD) in pre-treated orthodontic patients. MATERIAL AND METHODS: The study involved an experimental group of 107 pre-treated orthodontic patients with signs and symptoms of TMD aged 18-32 years, and a control group of 70 students with no signs and symptoms of TMD aged 20-30 years. The psychological condition of subjects was evaluated using two standard questionnaires, and a clinical examination performed to assess masticatory musculature and temporomandibular joint (TMJ) function, and to establish the presence or absence of TMD. Helkimo indices, the anamnestic dysfunction index (Ai) and the clinical dysfunction index (Di), were determined. Dental casts were mounted on a semi-adjustable articulator in CR using a CR bite record taken by bilateral manipulation and verified by load testing and face bow records. Differences in condylar position between CR and MI in the three planes of space were determined using the condyle position indicator. RESULTS: A positive CR-MI discrepancy, defined as a discrepancy exceeding 1 mm in the vertical or horizontal planes or 0.5 mm in the transverse plane, was found in 72.9% of the experimental and 11.4% of the control group. Comparison of the groups showed a significant difference (χ² = 22.67, P < 0.001). CR-MI discrepancy was significantly correlated with Di and Ai in all subjects (P < 0.01). CONCLUSIONS: There was CR-MI discrepancy in most of the pre-treated patients with signs and symptoms of TMD. This discrepancy may be a contributory factor to the development of TMD in these patients.

[The measurement of utility value for skeletal malocclusion].

OBJECTIVE: To measure the utility value of different skeletal malocclusion for patients receiving orthodontic treatment. METHODS: Utility value of different skeletal malocclusion for patients was measured by rating scale and time trade-off. RESULTS: The youth group had higher utility values than adult group for skeletal malocclusion Class II (protruding facial type) with median mandibular angle. The utility value of skeletal malocclusion Class III (concave facial type) with low mandibular angle was the lowest, and the utility value of skeletal malocclusion Class II (protruding facial type) with median mandibular angle was the highest. There was no difference in the utility values by rating scale and by time trade-off. CONCLUSION: For some skeletal malocclusion, the youth had different utility values with the adult.