Cone-beam computed tomographic characteristics in degenerative temporomandibular joint disease patients with chewing side preference.

OBJECTIVES: This study is aimed at assessing the Cone-beam computed tomographic (CBCT) characteristics of temporomandibular joints (TMJ) in degenerative temporomandibular joint disease (DJD) patients with chewing side preference (CSP). MATERIALS AND METHODS: CBCT images of 98 patients with DJD (67 with CSP and 31 without CSP) and 22 asymptomatic participants without DJD were measured retrospectively to compare the osteoarthritic changes and the morphology of TMJ. Quantitative analysis of the TMJ radiographic images was performed to present a comparison between the three inter-group groups and between the two sides of the joints. RESULTS: The frequencies of the articular flattening and surface erosion occur more often in the preferred side joints of DJD patients with CSP than the contralateral side. In addition, the horizontal angle of condyle, the depth of glenoid fossa (DGF), and the inclination of articular eminence (IAE) were larger in DJD patients with CSP than that in asymptomatic participants (p<0.05). Also, the condylar anteroposterior dimension of preferred side joints was significantly less than that of non-preferred side (p=0.026), while the width of condyles (p=0.041) and IAE (p=0.045) was greater. CONCLUSIONS: DJD patients with CSP appear to have a higher prevalence of osteoarthritic changes, with the morphological changes such as flat condyle, deep glenoid fossa, and steep articular eminence, which might be considered the characteristic imaging features. CLINICAL RELEVANCE: This study found that CSP is a predisposing factor for the development of DJD, and attention should be paid to the existence of CSP in DJD patients during the clinical practice.

A comparative study of condyle position in temporomandibular disorder patients with chewing side preference using cone-beam computed tomography.

BACKGROUND: Chewing side preference (CSP) could cause structural and morphological changes of temporomandibular joint (TMJ) and has been suggested as one aetiology of temporomandibular disorders (TMDs), but the condylar position in TMD patients with CSP is unknown. OBJECTIVE: To compare the condylar position in the TMD patients with and without CSP. METHODS: Ninety TMD patients with unilateral symptom (69 with CSP and 21 without CSP) and 20 asymptomatic participants received cone-beam computed tomography. The condylar position was determined based on the measurements of sagittal joint spaces. Intergroup and intra-group comparisons of the condylar position were performed. RESULTS: The condyles in asymptomatic participants located nearly randomly in anterior, centric and posterior positions. Patients without CSP had significantly more posterior condyles than asymptomatic participants (57.1% vs 30.0%, p < 0.05). In patients with CSP, 50.7% of the condyles on the preferred chewing side and 42.0% on the unpreferred side located posteriorly, reaching no significant level compared with the asymptomatic participants and patients without CSP (p > 0.05). The symptomatic joints and asymptomatic joints in patients with CSP and without CSP showed no significant differences in condylar position. While patients without CSP had significantly more posterior condyles in symptomatic joints than asymptomatic participants (p < 0.05), patients with CSP showed a trend towards more posterior condyles in symptomatic joints compared with the asymptomatic participants (53.6% vs 30.0%, p = 0.054). CONCLUSION: Condylar position is not a strong indicator to differentiate CSP-related TMDs from non-CSP-related TMDs. Posterior condyle could not be viewed as one indicator of TMD.

Memory impairment of chewing-side preference mice is associated with 5-HT-BDNF signal pathway.

Although tooth loss is a known risk factor of cognitive function, whether and how the chewing-side preference (CSP) affects memory impairment still remains unclear. This study evaluates the behavior changes in mice after the loss of teeth on one side and explores the role of serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) signal pathway within these changes. To this end, CSP mouse models with either the removal of left unilateral molars (CSP-L) or right unilateral molars (CSP-R) were established. Morris water maze test and passive avoidance test were performed to evaluate the mice's learning and memory capacity in the 4th and 8th weeks. The correlation between CSP and brain function changes was validated with changes in 5-HT and BDNF levels. CSP mice's cognitive function was found to be decreased, along with a significant decline in 5-HT1A level, especially in CSP-R mice. BDNF and TrkB levels in CSP-R mice were also significantly lowered. These findings suggest that CSP results in memory impairment, which is associated with the 5-HT-BDNF signaling pathway.