OBJECTIVES: The objective of this study is to measuring the morphology and position of bilateral temporomandibular joints in patients with unilateral and bilateral molar scissor bite and simulating the deformation of the mandible during occlusion, in order to provide thesis for the diagnosis of temporomandibular joint disease in patients with unilateral and bilateral molar scissor bite. METHODS: This study was a retrospective study. A total of 10 patients with unilateral molar scissor bite (the unilateral molar scissor bite group) and 10 patients with bilateral molar scissor bite (the bilateral molar scissor bite group) were selected as the experimental group, and 20 adult patients with classⅠ of angle classification of similar ages were selected as the control group. All patients underwent cone beam computed tomography scans, by measuring the width of the fossa, height of the fossa, articular eminence inclination, long axis of the condyle, minor axis of the condyle, horizontal angle of the condyle and the space of the temporomandibular joint, compare temporomandibular joint morphology and position. The three-dimensional finite element analysis of the mandible morphology was carried out to evaluate the force and deformation of the mandible by using software to simulate the occlusion of the patients. It was further explored the relationship between the force of the mandible morphology and the possible temporomandibular joint disorder symptoms of the patients. RESULTS: Intergroup comparisons for the unilateral molar scissor bite group and left sides of the other groups revealed that the superior articular space in the group with unilateral molar scissor bite was shorter than that in the control group (P<0.05); the long axis of the condyle in the unilateral and bilateral molar scissor bite group were both shorter than that of the control group (P<0.05); among which the unilateral group was larger than the bilateral group, and the minor axis of the condyle in bilateral molar scissor bite group was smaller than in the control group (P<0.05), and the unilateral and bilateral condylar groups were larger than the control group (P<0.05); and the condylar horizontal angle in the unilateral and bilateral groups were larger than that in the control group (P<0.05). The normal sides of the unilateral molar scissor bite group and right sides of the other groups had smaller superior articular space than the control group (P<0.05); and the condylar long-axis in bilateral group was smaller than the control group (P<0.05); and the normal side of the condylar short-axis unilateral group was larger than that of the bilateral condylar group. Three-dimensional finite element analysis: the condyle of patients with molar scissor bite was a concentrated area of deformation during the bite of the mandible, when the first molar occlusion of the scissors bite side was simulated, the maximum deformation was located in the condyle in the X-axis and Z-axis directions. The amount of deformation was greater than that of the scissor bite side in the X-axis direction, while in the Z-axis direction, the normal side was greater than the scissor bite side. The maximum sites of local deformation in the X-axis direction were located in anterior and posterior the transverse crest of scissor bite side, and the minimum sites of local deformation was at 1/3 of the anterior slope of the inner pole of the normal side, the maximum local deformation sites in the Z-axis direction were located in the outer pole and below the outer pole of the normal side. The X-axis deformation value was the largest in the molars occlusion on the normal side, the Y-axis deformation value was in the premolars occlusion on the normal side, and the Z-axis deformation value was the largest in the centric occlusion, the deformation value of the condyle was not most significant in molar scissor bite. CONCLUSIONS Unilateral and bilateral molar scissor bite resulting in a short condyle morphology, and the bilateral group had a shorter condylar morphology than the unilateral group. The condyle of the patient with molar scissor bite is a concentrated area of poor occlusal deformation, and the largest sites of deformation are distributed near the transverse ridge of the inner and outer poles of the condyle. Different occlusion conditions have an effect on condylar deformation values, but do not indicate whether there is a clear association between them.
Humans ; Finite Element Analysis ; Retrospective Studies ; Temporomandibular Joint/pathology* ; Cone-Beam Computed Tomography ; Mandible/pathology* ; Imaging, Three-Dimensional ; Adult ; Temporomandibular Joint Disorders/diagnostic imaging* ; Mandibular Condyle/diagnostic imaging* ; Female ; Male ; Molar

OBJECTIVES: Magnetic resonance imaging (MRI) was used to study the efficacy of modified anterior splint (MAS) combined with anterior repositioning splint (ARS) in maintaining the normal disk-condyle relationship. METHODS: We obtained clinical and imaging data of 10 patients with acute anterior disk displacement without reduction (ADDwoR) of the temporomandibular joint undergoing successful mandibular manipulation in the Affiliated Stomatological Hospital, Nanchang University from January to June 2024. The MAS and ARS were used for subsequent treatment. Maximum active mouth opening (MMO) and visual analogue score (VAS) were recorded before treatment and 2 weeks, 1 month, and 3 months after treatment. The changes in the disk-condyle relationship, disk-condyle angle, joint effusion, and double contour sign before and after treatment were analyzed through MRI. RESULTS: Three months after treatment, the MMO increased from 28.90 mm to 46.85 mm, VAS decreased from 4.68 to 0.61, and the disk-condyle angle decreased from 58.84° to 25.99°. MRI analysis found that 6 patients showed normal disk-condyle relationship, 2 patients exhibited displacement with reduction, and 2 patients exhibited ADDwoR. The disk-condyle angle was 58.84° before treatment and 25.99° after treatment. CONCLUSIONS The MAS combined with ARS could further stabilize the coordinated disk-condyle relationship and reduce the recurrence rate.
Humans ; Male ; Magnetic Resonance Imaging ; Female ; Adult ; Temporomandibular Joint Disorders/diagnostic imaging* ; Splints ; Middle Aged ; Mandible ; Temporomandibular Joint Disc ; Occlusal Splints ; Temporomandibular Joint ; Young Adult ; Joint Dislocations/therapy*

OBJECTIVES: This study aims to analyze the clinical symptoms and imaging manifestations in patients with temporomandibular disorder syndrome (TMD), who are sensitive to sudden temperature drop. METHODS: One hundred and nineteen patients with TMD who attended the Department of Stomatology of the First Medical Center of Chinese People's Liberation Army General Hospital from December 2022 to December 2023 were included, including 44 males and 75 females, with a mean age of 32.4±13.7 years.The questionnaire was used to determine whether they were sensitive to temperature drop, and the TMD patients were divided into a temperature plunge-sensitive group and a temperature drop insensitive group. The clinical symptoms and imaging manifestations of patients in the two groups were observed. SPSS 25.0 was used for statistical analysis. RESULTS: There was no statistically significant difference between the gender and age of patients in the temperature plunge-sensitive group (50 patients) and the insensitivity group (69 patients) (P>0.05). The percentage of patients with pain was slightly higher in the temperature plunge-sensitive group [86.0% (43/50)] than in the insensitive group [68.1% (47/69)], and the difference was statistically significant (χ²=5.031, P=0.025), while the differences in joint murmur and mouth opening limitation between the two groups were not statistically significant. A total of 238 lateral joints were detected in both groups, the percentage of osteoarthropathic imaging changes was significantly higher in the temperature plunge-sensitive group [82.0% (82/100)] than in the insensitive group [53.6% (74/138)] (χ²=20.675, P<0.001). Magnetic imaging showed that the percentage of joint effusion was higher in patients in the temperature plunge-sensitive group [66.0% (33/50)] than in the insensitive group [42.0% (29/69)], and the difference was statistically significant (χ²=5.602, P=0.018). CONCLUSIONS TMD patients with maxillofacial pain symptoms, joint effusions, and abnormal imaging of osteoarticular structures are more likely to be sensitive to sudden temperature drops.
Humans ; Male ; Female ; Adult ; Temporomandibular Joint Disorders/diagnosis* ; Surveys and Questionnaires ; Middle Aged ; Young Adult ; Temperature ; Adolescent

OBJECTIVES: This study aimed to investigate the association between temporomandibular disorder (TMD) and insomnia using a two-sample Mendelian randomization (MR) approach. METHODS: Bidirectional MR analyses of two samples, TMD (n=377 277) and insomnia (n=375 359), were performed using genome-wide association study statistics published in the FinnGen database. Instrumental variables were first screened, and then inverse variance weighting (IVW) and MR-Egger were used as the main-effect assessment methods. Weighted median, weighted mode, and simple mode served as supplementary methods. We used IVW and MR-Egger to test for heterogeneity, as well as MR-Egger intercepts to assess the single nucleotide polymorphism (SNP) potential level of multiplicity effects. Sensitivity analyses were conducted based on leave-one-out to identify potentially influential SNPs. All analyses were conducted by using the two-sample MR R package and were considered statistically significant when P<0.05. RESULTS: MR analysis showed the presence of TMD on insomnia (OR=1.089, 95%CI: 1.017-1.166, P=0.014). Meanwhile, no effect of insomnia on TMD (OR=0.996, 95%CI: 0.964-1.029, P=0.816) was found. The sensitivity-analysis showed that no heterogeneity existed (P>0.05), and the presence of horizontal pleiotropy was not detected (P>0.05). Leave-one-out sensitivity analysis showed no single SNP, which may affect the causal relation. All findings indicated that the causal relationship between TMD and insomnia was not significantly affected by any individual SNP and that IV did not bias the results. CONCLUSIONS Results of MR analyses showed that TMD is a risk factor for insomnia, whereas insomnia is not a risk factor for TMD.
Humans ; Sleep Initiation and Maintenance Disorders/genetics* ; Mendelian Randomization Analysis ; Polymorphism, Single Nucleotide ; Temporomandibular Joint Disorders/complications* ; Genome-Wide Association Study

OBJECTIVES: This study aimed to evaluate the effect of disc morphology and disc-condyle angle on the treatment of anterior repositioning splint (ARS) for anterior disc displacement with reduction (ADDwR). METHODS: On the basis of the inclusion and exclusion criteria, a total of 11 patients diagnosed with ADDwR were included. The effects of changes in disc length, thickness, and morphology classifications on the clinical symptoms, disc morphology parameters, and disc-condyle angles after ARS treatment were evaluated using magnetic resonance imaging and the Helkimo index. RESULTS: After ARS treatment, the Ai and Di of all patients with ADDwR decreased, the disc length increased, and the thickness decreased. The Ai of patients with slight ADDwR and those with type 1 joint discs was reduced to 0, with the most significant decrease observed in Di. The disc length of mild ADDwR (increased to 8.65 mm±1.79 mm) and type 5 disc (increased to 10.71 mm±2.62 mm) significantly increased the most. The disc thickness of slight ADDwR decreased to 3.08 mm±0.51 mm significantly. CONCLUSIONS The therapeutic effect of ARS is correlated with the displacement degree and morphological features of the disc, providing evidence for clinical treatment decisions.
Humans ; Magnetic Resonance Imaging ; Conservative Treatment ; Temporomandibular Joint Disc/diagnostic imaging* ; Male ; Adult ; Female ; Intervertebral Disc Displacement/pathology* ; Middle Aged

OBJECTIVES: This study aimed to investigate the correlation between clinical symptoms and unilateral chewing habits in patients with temporomandibular disorder (TMD) accompanied by tinnitus. METHODS: A total of 285 patients diagnosed with TMD at the Department of Stomatology of the First Medical Center of Chinese People's Liberation Army General Hospital between December 2020 and May 2024 were included and divided into two groups: tinnitus group and non-tinnitus group. Analysis was conducted on the proportion of patients with unilateral chewing habits in both groups, the correlation between the side of tinnitus and the side of unilateral chewing, and the correlation of tinnitus with TMD clinical symptoms (joint clicking, joint pain, and limited mouth opening) and unilateral chewing habits. The correlation of the type of disc displacement with unilateral chewing and tinnitus was also examined. RESULTS: In the tinnitus group, the proportions of patients with and without unilateral chewing habits were 90.70% (39/43) and 9.30% (4/43), respectively. In the non-tinnitus group, the proportions of patients with and without unilateral chewing habits were 76.03% (184/242) and 23.97% (58/242), respectively. The proportion of patients with unilateral chewing habits in the tinnitus group was significantly higher than in the non-tinnitus group (χ²=4.613, P<0.05). Correlation analysis showed a positive correlation between tinnitus and unilateral chewing habits (P<0.05). In the left-sided tinnitus group, the proportion of left-sided unilateral chewers [54.55% (12/22)] was higher than that of right-sided unilateral chewers [45.45% (10/22)]. In the right-sided tinnitus group, the proportion of right-sided unilateral chewers [81.82% (9/11)] was higher than that of left-sided unilateral chewers [18.18% (2/11)]. The difference was statistically significant (χ²=7.282, P<0.05). A positive correlation was also found between the side of tinnitus and the side of unilateral chewing habits (P<0.05). The proportion of patients with pain was significantly higher in the tinnitus group than in the non-tinnitus group (P<0.05). No significant difference in the proportion of joint clicking or limited mouth opening and disc displacement (no disc displacement, unilateral disc displacement, bilateral disc displacement, reducible disc displacement, or irreducible disc displacement) was found between the tinnitus and non-tinnitus groups (P>0.05). CONCLUSIONS TMD with unilateral chewing habits may be a contributing factor to unexplained tinnitus. Unexplained tinnitus is correlated with joint pain in patients with TMD.
Humans ; Tinnitus/physiopathology* ; Temporomandibular Joint Disorders/physiopathology* ; Mastication ; Male ; Adult ; Female ; Middle Aged ; Habits

OBJECTIVES: This retrospective study aimed to investigate factors influencing positional changes of the condyle and temporomandibular joint (TMJ) following mandibular defect reconstruction with bone flaps, and to evaluate the biomechanical impacts of flap reconstruction on condylar positioning, thereby providing evidence for optimizing surgical protocols and TMJ functional rehabilitation. METHODS: A retrospective study was conducted on 90 patients undergoing mandibular segmental resection with immediate bone flap reconstruction at Guizhou Medical University Affiliated Stomatological Hospital (June 2019 to May 2024). After strict screening, 50 cases with complete data were analyzed. Clinical parameters (defect size, location, reconstruction method) and craniofacial CT scans at four timepoints [preoperative (T0), 7-10 days (T1), 3 months (T2), and 6 months (T3) postoperatively] were collected. Mimics 20 software facilitated 3D reconstruction for measuring TMJ anterior/posterior/superior joint spaces (Kamelchuk method) and calculating condylar position via the Pullinger index [Ln (posterior/anterior space)]. Vitral and Krisjane methods quantified mandibular linear parameters (ramus length, condylar pole distances to the sagittal plane, angulation) and glenoid fossa morphology. Statistical analyses were performed using SPSS 21.0. RESULTS: Mandibular defect size and location were significant factors influencing postoperative condylar position changes (P<0.05). Compared to preoperative measurements, postoperative condylar anterior, posterior, and superior joint spaces were significantly increased (P<0.001). The most pronounced anterior condylar displacement occurred within 7-10 days postoperatively (P<0.05). In patients with condyle resection, postoperative joint space and angle changes were significant; in patients with condyle preservation, only superior and anterior joint space changes were statistically significant (P<0.05). Additionally, from T1 to T2, the changes in condylar medial-lateral distance, superior joint space, and anterior joint space were negatively correlated with the preoperative condylar position. Compared with preoperative,in the T0-T1 period, condylar medial-lateral distance, posterior joint space, and articular tubercle angle changes were significantly negatively correlated with time (P<0.05). Notably, the angle between the condylar long axis and the coronal axis showed a sustained negative trend from T1 to T3 (P<0.05). CONCLUSIONS Condylar position changes after mandibular defect repair with bone flap reconstruction are associated with the size and location of the defect. Additionally, adaptive remodeling of the temporomandibular joint (TMJ) joint space occurs postoperatively. The phenomenon of anterior displacement of the condyle in the early postoperative period (7-10 days) shows a trend of reduction with prolonged follow-up time, and further sample size research is needed.
Humans ; Retrospective Studies ; Temporomandibular Joint/surgery* ; Mandibular Condyle/surgery* ; Male ; Female ; Adult ; Middle Aged ; Mandibular Reconstruction/methods* ; Mandible/surgery* ; Surgical Flaps ; Tomography, X-Ray Computed ; Young Adult ; Biomechanical Phenomena ; Aged ; Adolescent ; Imaging, Three-Dimensional

OBJECTIVE: To explore the efficacy differences among different acupuncture frequencies for pain of temporomandibular disorders (TMD). METHODS: A total of 42 patients with TMD pain were randomly divided into a low-frequency group, a medium-frequency group, and a high-frequency group, with 14 patients in each group. All groups received acupuncture treatment at bilateral Hegu (LI4) and Yanglingquan (GB34), as well as ipsilateral Tinggong (SI19), Jiache (ST6), and Xiaguan (ST7), with each session lasting 30 minutes. The low-frequency group received acupuncture once per week, the medium-frequency group received acupuncture twice per week, and the high-frequency group received acupuncture three times per week, for a total duration of four weeks. The graded chronic pain scale (GCPS) score, visual analogue scale (VAS) score, jaw functional limitation scale-20 (JFLS-20) score, and pressure pain threshold (PPT) were assessed in the three groups before and after treatment, as well as at the four-week follow-up after treatment completion. RESULTS: Compared before treatment, GCPS and JFLS-20 scores were significantly decreased in all the groups after treatment (P<0.05), and VAS scores were significantly decreased in the high-frequency and medium-frequency groups (P<0.05), PPT values at different measurement sites were increased significantly in the high-frequency group (P<0.05). After treatment, GCPS, JFLS-20, and VAS scores in the high-frequency group were lower than those in the medium-frequency and low-frequency groups (P<0.05), while some PPT values were higher than the other two groups (P<0.05). At follow-up, GCPS, JFLS-20, and VAS scores remained significantly lower in all the groups compared to baseline (P<0.05), PPT values were increased significantly in the high-frequency and medium-frequency groups (P<0.05), with the high-frequency group showing lower GCPS, JFLS-20, and VAS scores and higher PPT values compared to the other two groups (P<0.05). CONCLUSION Acupuncture three times per week is more effective in reducing TMD pain intensity compared to once or twice per week, and can also alleviate some mandibular functional impairments. The therapeutic effects persist for at least four weeks after treatment completion.
Humans ; Male ; Female ; Adult ; Acupuncture Therapy/methods* ; Temporomandibular Joint Disorders/physiopathology* ; Middle Aged ; Young Adult ; Treatment Outcome ; Acupuncture Points ; Pain Management ; Adolescent ; Pain Measurement

Temporomandibular joint osteoarthritis (TMJ-OA) is a common disease often accompanied by pain, seriously affecting physical and mental health of patients. Abnormal innervation at the osteochondral junction has been considered as a predominant origin of arthralgia, while the specific mechanism mediating pain remains unclear. To investigate the underlying mechanism of TMJ-OA pain, an abnormal joint loading model was used to induce TMJ-OA pain. We found that during the development of TMJ-OA, the increased innervation of sympathetic nerve of subchondral bone precedes that of sensory nerves. Furthermore, these two types of nerves are spatially closely associated. Additionally, it was discovered that activation of sympathetic neural signals promotes osteoarthritic pain in mice, whereas blocking these signals effectively alleviates pain. In vitro experiments also confirmed that norepinephrine released by sympathetic neurons promotes the activation and axonal growth of sensory neurons. Moreover, we also discovered that through releasing norepinephrine, regional sympathetic nerves of subchondral bone were found to regulate growth and activation of local sensory nerves synergistically with other pain regulators. This study identified the role of regional sympathetic nerves in mediating pain in TMJ-OA. It sheds light on a new mechanism of abnormal innervation at the osteochondral junction and the regional crosstalk between peripheral nerves, providing a potential target for treating TMJ-OA pain.
Animals ; Osteoarthritis/physiopathology* ; Mice ; Sympathetic Nervous System/physiopathology* ; Temporomandibular Joint Disorders/physiopathology* ; Arthralgia ; Sensory Receptor Cells ; Disease Models, Animal ; Norepinephrine ; Male ; Temporomandibular Joint/physiopathology* ; Pain Measurement

The ambiguity of etiology makes temporomandibular joint osteoarthritis (TMJOA) "difficult-to-treat". Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management. Nonetheless, challenges such as low yields and insignificant efficacy of current exosome therapies necessitate significant advances. Addressing lower strontium (Sr) levels in arthritic synovial microenvironment, we studied the effect of Sr element on exosomes and miRNA selectively loading in synovial mesenchymal stem cells (SMSCs). Here, we developed an optimized system that boosts the yield of SMSC-derived exosomes (SMSC-EXOs) and improves their miRNA profiles with an elevated proportion of beneficial miRNAs, while reducing harmful ones by pretreating SMSCs with Sr. Compared to untreated SMSC-EXOs, Sr-pretreated SMSC-derived exosomes (Sr-SMSC-EXOs) demonstrated superior therapeutic efficacy by mitigating chondrocyte ferroptosis and reducing osteoclast-mediated joint pain in TMJOA. Our results illustrate Alix's crucial role in Sr-triggered miRNA loading, identifying miR-143-3p as a key anti-TMJOA exosomal component. Interestingly, this system is specifically oriented towards synovium-derived stem cells. The insight into trace element-driven, site-specific miRNA selectively loading in SMSC-EXOs proposes a promising therapeutic enhancement strategy for TMJOA.
MicroRNAs/metabolism* ; Mesenchymal Stem Cells/drug effects* ; Osteoarthritis/drug therapy* ; Exosomes/drug effects* ; Strontium/pharmacology* ; Synovial Membrane/cytology* ; Humans ; Animals ; Temporomandibular Joint Disorders/therapy* ; Temporomandibular Joint