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.

Association between chewing side preference and MRI characteristics in patients with anterior disc displacement of the temporomandibular joint.

OBJECTIVE: To compare the magnetic resonance imaging (MRI) characteristics in the anterior disc displacement (ADD) patients with and without chewing side preference (CSP). METHODS: The MRI characteristics of the bilateral temporomandibular joint (TMJ) in 111 patients with ADD were retrospectively analysed. Based on the presence of CSP, all subjects were divided into the non-CSP group (NC group, N = 40) and CSP group (C group, N = 71). Based on the preferred chewing side in the C group, the patients were divided into ipsilateral and contralateral sides. The morphology, length, disc-condyle angle, and coordinate position of the disc and condyle of the bilateral TMJ were compared. RESULTS: MRI examination showed a significant difference between ipsilateral and contralateral joint displacement in patients with CSP (P<0.05). In CSP patients, the disc length of the same side in the ipsilateral side was significantly shorter than the contralateral side (P<0.05). A significant difference in the Y-axis coordinates of the ipsilateral and contralateral discs was also found in patients with CSP (P<0.05). The disc displacement grade, morphology of the articular disc, ipsilateral disc length, and ipsilateral disc-condyle Y-axis distance were positively correlated with CSP (P<0.05). CONCLUSION: CSP is related to the shape of the articular disc and disc-condyle position in patients with ADD. CSP may aggravate the development of ADD.

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.

Occlusal analysis of patients with chewing side preference and symptoms of temporomandibular disorders.

OBJECTIVES: In this study, TeeTester digital occlusal analysis system was used to analyse the occlusal characteristics of chewing side preference (CSP) and non-CSP patients with TMD symptoms. METHODS: According to the questionnaire and oral examination, 80 subjects were screened and divided into four groups: 20 CSP patients with TMD symptoms, 20 CSP patients without TMD symptoms, 20 non-CSP patients with TMD symptoms, 20 non-CSP patients without TMD symptoms. TeeTester digital occlusal system was applied to measure the occlusal characteristics in all four groups, including total contect area (TCA), total occlution force (TOF), distribution of occlusal force (DOF), asymmetric index of occlusal force (AOF), occlusal time (OT), disclusion time (DT) and center of occlusal force(COF). SPSS 25.0 was used to analyze the statistical data. RESULTS: At intercuspal position, the data reveals significant differences in the maximum TOF and TCA among the four groups (P<0.05). There was significant difference in the distribution of occlusal force between the preferred side and the other side of CSP patients with or without TMD symptoms (P<0.05). Among the four groups, there were statistically significant difference in the position of the center point of occlusal force, the direction of the center point of occlusal force, and the vertical distance between the center point of occlusal force and the center line (P<0.05). The COF, maximum TOF and TCA of the preferred side of dentition were significantly positive correla⁃ted with CSP (P<0.05), according to Spearman correlation analysis. However, the maximum TOF and TCA of the both side of dentition were significantly negative correlated with TMD symptoms (P<0.05). CONCLUSIONS: 1) The occlusal characteristics of CSP patients and non-CSP patients with TMD symptoms are different. TeeTester digital occlusal analysis system provides objective parameters for the dynamic evaluation of occlusion. 2) Among all the occlusal cha⁃racteristics, maximum TOF, TCA and COF of the preferred side of dentition were positively correlated with CSP. The abnormal occlusal characteristics (maximum TOF and TCA of the whole dentition) caused by CSP are related to TMD symptoms.

Cone-beam computed tomographic assessment of the inclination of the articular eminence in patients with temporomandibular disorders and chewing side preference.

BACKGROUND: Chewing side preference (CSP) has been proposed as one etiology of temporomandibular disorders (TMDs) as it can induce the structural changes of the temporomandibular joint. But its association with the inclination of the articular eminence (IAE) is unknown. This study aimed to compare IAE between patients with CSP and without CSP. METHODS: Cone-beam computed tomography images of 90 patients with TMD (mean age of 45.6 years, 69 with CSP, 21 without CSP) and 20 participants without TMD and CSP (mean age of 41.3 years) were measured to compare IAE and depth of the glenoid fossa (DGF) RESULTS: IAE and DGF showed a positive correlation among all the participants. Compared with the participants without TMD and CSP, the TMD patients without CSP presented a similar IAE but with a significantly higher value of DGF (p < 0.05); in contrast, the TMD patients with CSP presented a significantly greater IAE and DGF (p < 0.05). No bilateral differences in IAE and DGF were observed in all the participants. Except the male patients with CSP had a deeper fossa than did the female, no differences in IAE and DGF according to gender were observed. CONCLUSIONS: TMD patients with CSP seem to have a deep glenoid fossa with steep eminence which might be considered one characteristic imaging feature.

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.