Clinical effect of digitalized designed and 3D-printed repositioning splints in the treatment of anterior displacement of temporomandibular joint disc.

OBJECTIVE: To compare the treatment effectiveness of digitized and 3D-printed repositioning splints with that of conventional repositioning splints in the treatment of anterior displacement of the temporomandibular joint disc. METHODS: This retrospective study included 96 patients with disc displacement of the anterior temporomandibular joint. They were treated with either digitally designed and 3D-printed repositioning splints or traditional splints and followed up for at least six months. Changes in signs and symptoms such as pain and mouth opening before and after treatment were recorded to evaluate treatment outcomes. RESULTS: During the first month of treatment, both the digitally designed and 3D-printed repositioning splint groups (Group B) and the traditional repositioning splint group (Group A) showed significant increases in mouth opening, with increases of 4.93 ± 3.06 mm and 4.07 ± 4.69 mm, respectively, and there was no significant difference between the two groups. Both groups had a significant reduction in visual analog scale (VAS) pain scores, with Group B showing a greater reduction of 1.946 ± 1.113 compared to 1.488 ± 0.978 in Group A (P < 0.05). By the sixth month, Group B's mouth opening further improved to 38.65 ± 3.22 mm (P < 0.05), while Group A's mouth opening did not significantly improve. Regarding pain, Group A's VAS score decreased by 0.463 ± 0.778 after one month, and Group B's score decreased by 0.455 ± 0.715; both groups showed significant reductions, but there was no significant difference between the two groups. CONCLUSION: Compared with traditional repositioning splints, digitally designed and 3D-printed repositioning splints are more effective at reducing patient pain and improving mouth opening. 3D-printed repositioning splints are an effective treatment method for temporomandibular joint disc displacement and have significant potential for widespread clinical application.

Reliability of magnetic resonance for temporomandibular joint disc perforation: A 12 years retrospective study.

The aim of this study was to evaluate the reliability of magnetic resonance imaging (MRI) in detecting disc perforations in the temporomandibular joint (TMJ), and to establish diagnostic criteria for this purpose. The retrospective analysis included patients who had undergone preoperative MRI and TMJ arthroscopy at the same hospital. Direct and indirect signs of disc abnormalities on MRI were compared with arthroscopic findings of disc perforation. Out of 355 joints evaluated in 185 patients, arthroscopy confirmed disc perforations in 14.7% of cases. Several MRI findings were significantly associated with disc perforation, including anterior disc displacement without reduction (ADDwoR), signal alterations in the mid-disc area, disc deformity (SAMD), retrocondylar disc fragments, osteophytes, condylar bone marrow degeneration (CBMD), and joint effusion in both joint spaces (ESJS-EIJS). Regression analysis revealed that SAMD, osteophytes, and CBDM were strongly associated with disc perforation. The ROC curve showed that MRI had an AUC = 0.791, with a sensitivity of 88.5% and a specificity of 61.5%. Two diagnostic methods, one based on three findings (osteophytes, ADDwoR, and SAMD) and one based on two direct signs (ADDwoR and SAMD), yielded high sensitivity and specificity values of 80.4% and 69.8%, and 84.3% and 62.5%, respectively. In conclusion, MRI demonstrated acceptable accuracy in the detection of TMJ disc perforations, with specific diagnostic criteria offering high sensitivity and specificity. Significant MRI indicators of disc perforation included SAMD, osteophytes, and CBDM. This study provides valuable information on the use of MRI as a diagnostic tool for TMJ disc perforations.

Comparison of the TMJ arthroscopy discopexy techniques: A systematic review and meta-analysis.

This article aims to analyze which of the main arthroscopic discopexy techniques has the best results and if there are differences between the techniques for both pain and maxillary intercuspid opening. A systematic review and meta-analysis was performed according to the PRISMA statement. An electronic search was performed with no publication date restriction in PubMed, Ovid and Embase. The PICO criteria: (P) Patients: With temporomandibular internal disorders with discopexy indication. (I) Intervention: Temporomandibular joint arthroscopic discopexy. (C) Comparison: Arthroscopic discopexy among different techniques classified as non-rigid, semi-rigid and rigid. (O) Outcomes: Impact in clinical conditions such as pain and maximum mouth opening. The inclusion criteria were Patients with temporomandibular internal disorders with discopexy indication performed with different techniques classified as non-rigid, semi-rigid and rigid. The outcomes evaluated were pain and maximum mouth opening. Case series, cohort studies, quasi-experimental studies, and randomized clinical trials with at least 3 months of follow-up were included. The exclusion criteria considered were patients with related concomitant surgeries, patients with associated neoplastic disease or connective tissue disease. A total of 1515 joints where 1400 discopexies were performed including 849 females and 204 males. The most common diagnostic was Wilkes stage III in 257 joints. For pain and oral opening, the semi-rigid technique shows the best results median (MD) 4.84 (CI 2.52-7.16; p = 0.001, I2:100%), MD -2.78 (CI -4.34, -1.21; p = 0.001, I2:99%), respectively. The rigid technique has the greatest probability for complications MD 0.14 CI 95% (0.00, -0.28). Although the semi-rigid technique showed better results, there is no statistically significant difference. However, due to the heterogeneity of the studies, the results should be interpreted with caution.

Contribution of the complex comprising the masticatory fascia, disc, and capsule to temporomandibular joint stabilization: An anatomical study.

BACKGROUND: Anterior displacement of the temporomandibular joint (TMJ) disc is the most typical pathological condition of TMJ disorders. Structures attached to the articular disc may support the disc in various directions and contribute to stabilizing the TMJ. However, the relationship between the articular disc, capsule, and masticatory muscles remains unclear. Therefore, this study aimed to clarify the relationship between the masticatory muscles, related masticatory fascia, articular disc, and capsule. METHODS: We examined 10 halves from adult Japanese cadavers, with five halves macroscopically analyzed and the remaining five histologically analyzed. The TMJ was dissected from the lateral aspect for gross anatomical analysis. For histological analysis, the relationship between the temporal and masseteric fasciae and the articular capsule was observed in the coronal section. Additionally, we evaluated relationships among the disc, capsule, temporal fascia, and masseteric fascia in 10 living and healthy volunteers using magnetic resonance imaging. RESULTS: The articular disc was attached to the capsule without a clear border. The capsule continued into the masseteric and temporal fasciae. Consequently, the articular disc, capsule, masseteric, and temporal fasciae were considered a single complex. CONCLUSIONS: The single complex of the temporalis, masseter, capsule, masticatory fascia, and disc may antagonize the force in the posterolateral direction through the fascia.

Microstructural, Micromechanical Atlas of the Temporomandibular Joint Disc.

The temporomandibular joint (TMJ) disc is mainly composed of collagen, with its arrangement responding to efficient stress distribution. However, microstructural and micromechanical transformations of the TMJ disc under resting, functional, and pathological conditions remain unclear. To address this, our study presents a high-resolution microstructural and mechanical atlas of the porcine TMJ disc. First, the naive microstructure and mechanical properties were investigated in porcine TMJ discs (resting and functional conditions). Subsequently, the perforation and tear models (pathological conditions) were compared. Following this, a rabbit model of anterior disc displacement (abnormal stress) was studied. Results show diverse microstructures and mechanical properties at the nanometer to micrometer scale. In the functional state, gradual unfolding of the crimping cycle in secondary and tertiary structures leads to D-cycle prolongation in the primary structure, causing tissue failure. Pathological conditions lead to stress concentration near the injury site due to collagen interfibrillar traffic patterns, resulting in earlier damage manifestation. Additionally, the abnormal stress model shows collagen damage initiating at the primary structure and extending to the superstructure over time. These findings highlight collagen's various roles in different pathophysiological states. Our study offers valuable insights into TMJ disc function and dysfunction, aiding the development of diagnostic and therapeutic strategies for TMJ disorders, as well as providing guidance for the design of structural biomimetic materials.

Effect of the application of digital technology-assisted optimization in the process of adjusting jaw position.

OBJECTIVES: The aim of this study was to demonstrate a novel jaw position adjustment technique derived from digital twins and evaluate the application effect of digital technology-assisted optimization in the process of adjusting jaw position on patients with temporomandibular disorders (TMD). METHODS: A total of 74 patients with TMD who attended the Department of Temporomandibular Joint, West China Hospital of Stomatology, Si-chuan University, between June 2022 and May 2023 were selected. The patient's initial computed tomography (CT) and bilateral temporomandibular joint data obtained by magnetic resonance imaging (MRI) were collected. The 148 joints were divided into the normal disc-condyle relationship (N) group, disc displacement with reduction (DDWR) group, and disc displacement without reduction (DDWoR) group. Assisted by digital technology, the patient's CT data were reconstructed, and a personalized reference plane was established to adjust the jaw position. A three-point bite guiding splint was designed by the adjusted occlusal space and then fabricated by 3D printing technology. It was worn by the patients and then reviewed by MRI. Before and after the adjustment of jaw position, the amount and direction of condyle and disc displacement and the angle between condyle and disc were measured as the evaluation indexes of the effect of the adjustment. The correlation with condylar displacement was evaluated. RESULTS: In the N group, the disc moved backward and downward along the X and Z axes by (-0.60±0.62) and (0.51±0.71) mm, respectively. In the DDWR group, the disc moved backward and upward along the X and Z axes by (-1.33±1.38) and (-0.09±1.31) mm, respectively. In the DDWoR group, the disc moved forward and downward along the X and Z axes by (0.49±1.76) and (1.35±1.76) mm, respectively. The angle between the condyle and the disc decreased after adjustment of the jaw position in all three groups. All patients showed improvement in symptoms after adjustment. CONCLUSIONS: Digital technology-assisted jaw position adjustment can simplify the process, reduce the sensitivity of the technique, and improve patients' disc-condyle structure and symptoms. Therefore, its application in the treatment of patients with TMD is of great clinical significance.

A Three-branch Jointed Feature and Topology Decoder guided by game-theoretic interactions for temporomandibular joint segmentation.

Segmentation of the temporomandibular joint (TMJ) disc and condyle from magnetic resonance imaging (MRI) is a crucial task in TMJ internal derangement research. The automatic segmentation of the disc structure presents challenges due to its intricate and variable shapes, low contrast, and unclear boundaries. Existing TMJ segmentation methods often overlook spatial and channel information in features and neglect overall topological considerations, with few studies exploring the interaction between segmentation and topology preservation. To address these challenges, we propose a Three-Branch Jointed Feature and Topology Decoder (TFTD) for the segmentation of TMJ disc and condyle in MRI. This structure effectively preserves the topological information of the disc structure and enhances features. We introduce a cross-dimensional spatial and channel attention mechanism (SCIA) to enhance features. This mechanism captures spatial, channel, and cross-dimensional information of the decoded features, leading to improved segmentation performance. Moreover, we explore the interaction between topology preservation and segmentation from the perspective of game theory. Based on this interaction, we design the Joint Loss Function (JLF) to fully leverage the features of segmentation, topology preservation, and joint interaction branches. Results on the TMJ MRI dataset demonstrate the superior performance of our TFTD compared to existing methods.

Evaluating changes in the condylar head after orthognathic surgery with or without articular disc repositioning: a systematic review.

Failures in orthognathic surgery are associated with different factors, including those related to untreated or undiagnosed preoperative temporomandibular joint (TMJ) disorders. This systematic review aimed to assess potential alterations in the condylar head following orthognathic surgery. A systematic search for randomised controlled trials and retrospective studies was performed. For inclusion in the review, studies had to meet the following eligibility criteria according to the PICO framework: Patients: patients with orthognathic deformity and temporomandibular dysfunction (or temporomandibular osteoarthritis); Intervention: patients submitted to orthognathic surgery concomitantly with TMJ disjunction; Control: patients undergoing only orthognathic surgery with or without presurgical data; and Outcome: changes in temporomandibular joint position and volume. Nine studies met all the inclusion criteria and were selected for qualitative analysis. The results of this review show that simultaneous articular disc repositioning and orthognathic surgery provide better results in patients with preoperatively diagnosed condylar osteoarthritic changes. In conclusion, condylar remodelling (resorption/deposition) and its extent are determined by the direction of condylar displacement during surgery. Other factors such as age are also associated with the development of condylar resorption.

Comparative study of clinical and MRI features of TMD patients with or without joint effusion: a retrospective study.

BACKGROUND: The relationship between joint effusion and temporomandibular disorders (TMD) remains unclear. The purpose of this study was to investigate the correlation among joint effusion, clinical features and MRI imaging features of TMD. METHODS: A total of 1532 temporomandibular joints (TMJs) from 766 patients (605 females and 161 males) with the mean age of 31.68 ± 13.71 years from January 2022 to June 2023 were included in the study. Clinical and MRI features were collected and analyzed. Chi-Square test, Spearman correlation coefficient and binary logistic regression analysis were performed. RESULTS: Patients with joint effusion were significantly older and had smaller value of MIO (p < 0.001). There were significant differences in the distribution of joint sounds (with or without), joint pain (with or without), disc morphology (biconcave, contracture, irregular and lengthened) and disc position between joint effusion group (JE) and non-joint effusion group (NA) (P < 0.05).The odds of having joint effusion were 1.726 higher in patients with joint sounds when compared to those without joint sounds. The odds of having joint effusion were 8.463 higher in patients with joint pain when compared to those without joint pain. The odds of having joint effusion were 2.277 higher in patients with contracture when compared to those with biconcave. The odds of having joint effusion were 1.740 higher in patients with anterior disc displacement with reduction (ADDWR) when compared to those with normal disc position. The prediction accuracy of this model is 74.9%, and the area under curve (AUC) is 79.5%, indicating that it can be used for the prediction and the judgment effect is average. CONCLUSIONS: The results demonstrated that joint sounds, joint pain, contracture, and ADDWR are high risk factors for joint effusion, especially joint pain. TRIAL REGISTRATION: This study was retrospectively registered on 28/03/2022 and endorsed by the Ethics Committee of Affiliated Stomatology Hospital of Guangzhou Medical University (LCYJ2022014).

The utilization of decision trees on orthopantomographic and lateral panoramic graphs for the diagnosis of unilateral anterior disc displacement of the temporomandibular joint.

BACKGROUND: Investigation is to utilize decision trees in conjunction with orthopantomography (OPT) and lateral panoramic graphy (LPG) to diagnose unilateral anterior disc displacement (ADD) of the temporomandibular joint. METHODS: In this study, 161 patients with images obtained through all three imaging methods, MRI, OPT, and LPG, were selected from the archives. The participants were categorized into two groups: the study group, comprising 89 patients with unilateral anterior disc displacement, and the control group, consisting of 72 healthy individuals. Measurements, including 2 angles (antero-posterior angle and superior-inferior angle) and 3 distance parameters (anterior joint space distance, superior joint space distance, and posterior joint space distance), were conducted on each imaging modality dataset. To assess the obtained measurement data within each patient, the differences from each measurement were calculated. Statistical analysis of the measurement differences between the control and study groups was carried out with independent t test, and decision trees were generated using the SPSS 25 decision tree module 5.0. RESULTS: In ADD patients, it was statistically significantly found that the APA increased while the SIA decreased for angle measurements. But for linear measurements, AS increased while the SS and PS decreased in MRI, OPT, and LPG. CONCLUSION: ADD can be diagnosed in OPT and LPG. The identification of the specific type of ADD that occurs in the temporomandibular joint is not feasible.

Analysis of clinical changes and magnetic resonance imaging features of 37 patients with temporomandibular joint disc condylar complex with anterior disc displacement without reduction.

OBJECTIVES: This study aims to investigate clinical outcomes, imaging changes, and age differences with regard to temporomandibular joint disc condylar complex with anterior disc displacement without reduction (ADDWoR). METHODS: A total of 37 patients (45 lateral joints) with ADDWoR who were admitted to The First Affiliated Hospital of Zheng Zhou University from January 2016 to June 2023 were selected. The patients were composed of 4 males and 33 females and had an average age of 23.5 years. The average course of the disease was 14.4 months. Clinical and magnetic resonance imaging (MRI) data were collected at the end of initial diagnosis and follow-up, and the length and thickness of the articular disc, the angle of the disc condyle, and the height of the condyle were measured. The statistical significance of the changes was assessed using SPSS 25.0 software package. RESULTS: At the end of follow-up, disc displacement in three patients (three lateral joints) was healed. Approximately 48.4% of the patients felt that limitation of mandibular movement was not alleviated; 58.3% of patients reported that pain during mouth opening was not reduced; 54.5% reported pain while chewing; 33.3% of the patients showed facial deviation, and only one showed remission. The mean disk-condyle angle increased from 61.63° to 67.81°. The average length of articular disc shortened from 8.20 mm to 7.27 mm, and the height of the condyle significantly decreased from 23.17 mm to 22.76 mm (P<0.05). The absorption ratio of the condyle increased, and no significant differences in the changes of joint soft and hard tissues between the adolescent and adult groups (P>0.05). CONCLUSIONS: In different age groups of patients with ADDWoR, clinical symptoms cannot be completely relieved. The disc is anteriorly displaced and shortens, condylar height decreases, and secondary facial asymmetry and mandibular retraction occur.

Evidence for minimally invasive treatment-A systematic review on surgical management of disc displacement.

BACKGROUND: Surgical treatment of temporomandibular joint (TMJ) disc displacement (DD) has been established in different forms since over a century. Ther is a consensus to perform minimal invasive interventions as first-line surgical treatment since there are no evidence on best surgical practice yet. OBJECTIVE: The aim was to perform a complex systematic review (SR) on the topic-is there evidence for surgical treatment of TMJ DD? METHODS: The PICO was defined as DD patients (population), treated with different surgical interventions including arthrocentesis (intervention), compared with other or no treatment (control) regarding the outcome variables mandibular function, mouth opening capacity, TMJ pain, etcetera (outcome). For identification of prospective controlled trials and SRs, a search strategy was developed for application in three databases. RESULTS: The search yielded 4931 studies of which 56 fulfilled the stipulated PICO. Studies with low or moderate risk of bias were possible to include in meta-analyses. There were evidence suggesting arthrocentesis being more effective compared to conservative management (maximum interincisal opening (MIO): p < .0001, I2 = 22%; TMJ pain: p = .0003, I2 = 84%) and arthrocentesis being slightly more effective than arthrocentesis with an adjunctive hyaluronic acid injection (MIO: p = .04, I2 = 0%; TMJ pain: p = .28, I2 = 0%). Other treatment comparisons showed nonsignificant differences. The performed meta-analyses only included 2-4 studies each, which might indicate a low grade of evidence. CONCLUSION: Although arthrocentesis performed better than conservative management the findings should be interpreted cautiously, and non-invasive management considered as primary measure. Still, several knowledge gaps concerning surgical methods of choice remains.

Arthroscopic reduction and rigid fixation of the anteriorly displaced temporomandibular joint disc without reduction using titanium screw: a case series.

OBJECTIVES: To evaluate the effectiveness of arthroscopic reduction and rigid fixation (ARRF) using a suture-free titanium screw as a treatment approach to temporomandibular joint's (TMJ) anterior disc displacement without reduction (ADDwoR) and assess its impact on clinical outcomes, including improvements in symptoms related to TMJ disorders. MATERIALS AND METHODS: A series of twenty patients presented to the Department of Orthognathic and Temporomandibular Surgery at West China Hospital of Stomatology between September 2022 and January 2023, complaining of symptoms such as pain, clicking, and limited mouth opening. Standard magnetic resonance image (MRI) imaging T1 and T2 sequences in both sagittal and coronal views study with closed and maximal open mouth positions were taken preoperatively to assess the disc's position, integrity, and shape. Also, cone-beam computed tomography (CBCT) scans images to find any degenerative changes and evaluate the condylar bone's features and volume. Additionally, the clinical examination assesses limited oral opening, mechanical pain, and the presence of any noises such as clicking and crepitus. All cases were treated under general anesthesia using the arthroscopic release, reduction, and rigid fixation of the TMJ's ADDwoR to establish a normal disc-condyle relationship and to restore the functional position. RESULTS: Patients' symptoms, such as pain and mouth opening, improved significantly following the arthroscopic treatment. Postoperative MRI and CBCT imaging follow-up conducted at 6 months demonstrated the stable position of the reduced TMJ disc and the fixation screw. Notably, none of the patients exhibited signs of relapse during this follow-up period. CONCLUSION: Overall, the ARRF of TMJ's ADDwoR using a suture-free titanium screw proved to be safe and provides satisfactory results, in addition to the several advantages of using suture-free titanium screws, such as biocompatibility, strong fixation, and durability. However, it is a technically demanding procedure requiring extensive, long-term training. CLINICAL RELEVANCE: ARRF using a cost-effective fixation titanium screw to treat ADDwoR emerges as a clinically effective minimally invasive approach.

A New Technique for Arthroscopic Discectomy of the Temporomandibular Joint Disc Perforation: A Technical Note.

Disc perforation represents the result of the degenerative process in joint structures that may lead to pain, joint noise, restricted mouth opening, osteoarthritis, and even dentofacial anomalies. Even though discectomy has proven benefits, with promising outcomes reported, it is mainly described using an open approach. While some arthroscopic techniques have been published, they are limited to managing perforation, edge widening, and inflammation treatment and do not describe complete disc removal. We describe a novel step-by-step arthroscopic discectomy technique utilizing two operative cannulas that completely remove nonfunctional cartilaginous tissue.

Comparison of T2 values of the displaced unilateral disc and retrodiscal tissue of temporomandibular joints and their implications.

Unilateral anterior disc displacement (uADD) has been shown to affect the contralateral joints qualitatively. This study aims to assess the quantitative T2 values of the articular disc and retrodiscal tissue of patients with uADD at 1.5 Tesla (T). The study included 65 uADD patients and 17 volunteers. The regions of interest on T2 maps were evaluated. The affected joints demonstrated significantly higher articular disc T2 values (31.5 ± 3.8 ms) than those of the unaffected joints (28.9 ± 4.5 ms) (P < 0.001). For retrodiscal tissue, T2 values of the unaffected (37.8 ± 5.8 ms) and affected joints (41.6 ± 7.1 ms) were significantly longer than those of normal volunteers (34.4 ± 3.2 ms) (P < 0.001). Furthermore, uADD without reduction (WOR) joints (43.3 ± 6.8 ms) showed statistically higher T2 values than the unaffected joints of both uADD with reduction (WR) (33.9 ± 3.8 ms) and uADDWOR (38.9 ± 5.8 ms), and the affected joints of uADDWR (35.8 ± 4.4 ms). The mean T2 value of the unaffected joints of uADDWOR was significantly longer than that of healthy volunteers (P < 0.001). These results provided quantitative evidence for the influence of the affected joints on the contralateral joints.

Effectiveness of anterior repositioning splint versus other occlusal splints in the management of temporomandibular joint disc displacement with reduction: A meta-analysis.

BACKGROUND: Disc displacement with reduction (DDwR) is among the common disc disorders of temporomandibular joint (TMJ), which can be managed conservatively by splint therapy. Anterior repositioning splint (ARS) is the most commonly prescribed splint by dental practitioners, but not getting a normal disc-condyle relationship always and other side effects lead to need of comparing with other occlusal splints. This review will help in informed decision-making by clinicians in choosing an appropriate splint type for patients. AIM: The aim is to compare the effectiveness of ARS in the management of DDwR with other occlusal splints for TMJ and muscle pain, TMJ noise, any adverse effects, regaining normal disc-condyle relationship. MATERIALS AND METHODS: We followed published protocol in the International prospective register of systematic reviews. Databases were searched till May 2023 using different search strategies as per the database. Title and abstract screening, followed by full-text screening and data extraction with risk of bias, was done by two independent reviewers in Covidence. Outcomes were reported as risk ratio (RR) or mean difference (MD) for dichotomous or continuous outcomes, respectively, using RevMan 5.4 (Review Manager 5.4) software. We used a random effect model for statistical analysis. Certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation Guideline Development Tool (GRADEpro GDT) software. RESULTS: A total of 1145 reports were found from a database search. After screening, four studies were included for systematic reviews. Other occlusal splints reported were sagittal vertical extrusion device and mandibular ARS, full hard stabilization splint of canine or centric stabilization type. Data of only two studies could be used for meta-analysis having 30 participants received ARS and 40 received other occlusal splints. We did not find evidence of any difference between ARS and other occlusal splints for TMJ clicking in short term (RR 1.25, 95% confidence interval [CI] 0.91-1.72) but a small difference in favor of other occlusal splint in long term (RR 2.40, 95% CI 1.04-5.55). No evidence of any difference was found between both treatments for TMJ pain in short term (MD-5.68, 95% CI-17.31-5.95) and long term (MD 0.00, 95% CI-2.86-2.86) and muscle pain in short term. The certainty of evidence for comparison of two treatments for different outcomes was of low or very low level. CONCLUSION: Evidence is uncertain that other occlusal splints reduced TMJ clicking slightly in comparison to ARS. For the remaining outcomes, no evidence of any difference was found between the two splints and it may be biased due to selection bias, inadequate blinding of participants, and outcome assessor.

Correlation between temporomandibular joints and craniocervical posture in patients with bilateral anterial disc displacement.

OBJECTIVE: To study the changes of temporomandibular joints and craniocervical posture in adult patients with bilateral anterior disc displacement, and to explore their correlation, which may provide some clinical value for clinical diagnosis and treatment planning. METHODS: Ninety-eight adult patients were divided into 3 groups: 29 patients in bilateral disc normal position group (BN), 33 patients in bilateral Anterior Disc Displacement With Reduction group (ADDWR) and 36 patients in bilateral Anterior Disc Displacement Without Reduction group (ADDWoR). Dolphin and Uceph software were used to measure 14 items of temporomandibular joint and 11 items of craniocervical posture for comparison and correlation analysis between groups. RESULTS: There were significant differences in bilateral joint space between three groups. Compared with the BN, the anteroposterior diameter of the condyle was significantly reduced, the condyle was significantly displaced posteriorly and superiorly in the ADDWR and ADDWoR, but the joint fossa width and joint fossa depth did not change significantly. Cervical curvature and inclination were greater in patients with anterior disc displacement than BN, indicating that the craniocervical posture of adult patients with anterior disc displacement was extended and protrusive. CONCLUSION: Anterior disc displacement of the temporomandibular joint can displace the condyle upwards and posteriorly and reduce the anteroposterior diameter of condyle, and then make the condyle closer to the wall of articular fossa to induce joint symptoms. Additionally, craniocervical postural position is significantly affected, which may be related to compensate for the effects of airway space.

[A three-dimensional imaging study of the effect of anterior disc displacement on the bony structural relationship of the temporomandibular joint].

Objective: To investigate the correlation between the osseous structure of temporomandibular joint (TMJ) and three different status of anterior disc location, so that it could guide the clinical diagnosis further. Methods: Fifty-two patients [46 females and 6 males, with an age of (27.8±8.3) years] who treated with MRI and cone beam CT, were recruited from the Temporomandibular Joint Specialist Clinic, The First Affiliated Hospital of Xinjiang Medical University, between March 2018 to December 2021. According to the radiographic findings of the level of anterior disc displacement (ADD) in TMJ, patients were divided into three groups: normal articular disc position (NADP, n=28 TMJs), anterior disc displacement with reduction (ADDWR, n=28 TMJs), and anterior disc displacement without reduction (ADDWoR, n=28 TMJs). In the light of the reconstructed three-dimensional model, ten representative morphological parameters including condylar volume (CV), condylar superficial area (CSA), fossa volume (FV), fossa superficial area (FSA), the proportion of the condylar volume in the articular fossa (CV%), the proportion of the condylar superficial area in the articular fossa (CSA%), superior joint space (SJS), anterior joint space (AJS), posterior joint space (PJS), and medial joint space (MJS), were measured respectively under one-way analysis of variance (ANOVA), Kruskal-Wallis Htest and receiver operator characteristic curve(ROC curve) analyses. Results: CV and CSA values varied significantly in the pathological progression from normal location to irreversible anterior displacement in TMJ. For CV value, NADP group [(1 834.90±667.67) mm3]>ADDWR group [(1 747.34±369.42) mm3]>ADDWoR group [(1 256.29±418.27) mm3] [t=4.31, P(NADP-ADDWoR)<0.001; t=3.66, P(ADDWR-ADDWoR)<0.001], for CSA value, NADP group [(859.27±216.01) mm2]>ADDWR group [(838.23±118.82) mm2]>ADDWoR group [(669.14±150.26) mm2] [t=4.27, P(NADP-ADDWoR)<0.001; t=3.80, P(ADDWR-ADDWoR)<0.001]. The difference of SJS value in NADP group [(2.22±0.88) mm], ADDWR group [(1.94±0.64) mm] and ADDWoR group [(1.45±0.57) mm], was statistically significant [t=4.11, P(NADP-ADDWoR)<0.001; t=2.63, P(ADDWR-ADDWoR)=0.010]. The results of MJS in NADP group [(5.03±1.41) mm], ADDWR group [(3.86±1.32) mm], and ADDWoR group [(4.91±1.65) mm] were significantly different [t=3.00, P(NADP-ADDWR)=0.004; t=2.63, P(ADDWR-ADDWoR)=0.009]. As calculated by the ROC curve analysis, CV, CSA and SJS showed that (AUCCV=0.77, AUCCSA=0.76; AUCSJS=0.76) for the NADP and ADDWoR groups, and (AUCCV=0.80; AUCCSA=0.80; AUCSJS=0.72) for the ADDWR and ADDWoR groups. While the diagnostic accuracy of MJS for the comparison in NADP versus ADDWR and ADDWR versus ADDWoR was respectively AUC(NADP-ADDWR)=0.73, and AUC(ADDWR-ADDWoR)=0.69. Conclusions: CV, CSA, SJS, and MJS were significantly associated with the different disc displacement status, and the condyle in TMJ ADD exhibited three-dimensionally altered dimensions. They could be considered as promising biometric markers to diagnose the ADD status.

The effect of bolus properties on muscle activation patterns and TMJ loading during unilateral chewing.

Mastication is a vital human function and uses an intricate coordination of muscle activation to break down food. Collection of detailed muscle activation patterns is complex and commonly only masseter and anterior temporalis muscle activation are recorded. Chewing is the orofacial task with the highest muscle forces, potentially leading to high temporomandibular joint (TMJ) loading. Increased TMJ loading is often associated with the onset and progression of temporomandibular disorders (TMD). Hence, studying TMJ mechanical stress during mastication is a central task. Current TMD self-management guidelines suggest eating small and soft pieces of food, but patient safety concerns inhibit in vivo investigations of TMJ biomechanics and currently no in silico model of muscle recruitment and TMJ biomechanics during chewing exists. For this purpose, we have developed a state-of-the-art in silico model, combining rigid body bones, finite element TMJ discs and line actuator muscles. To solve the problems regarding muscle activation measurement, we used a forward dynamics tracking approach, optimizing muscle activations driven by mandibular motion. We include a total of 256 different combinations of food bolus size, stiffness and position in our study and report kinematics, muscle activation patterns and TMJ disc von Mises stress. Computed mandibular kinematics agree well with previous measurements. The computed muscle activation pattern stayed stable over all simulations, with changes to the magnitude relative to stiffness and size of the bolus. Our biomedical simulation results agree with the clinical guidelines regarding bolus modifications as smaller and softer food boluses lead to less TMJ loading. The computed mechanical stress results help to strengthen the confidence in TMD self-management recommendations of eating soft and small pieces of food to reduce TMJ pain.

Comparison of disc position stability and condylar bone remodelling between two open disc repositioning surgeries: a retrospective single-centre cohort study.

BACKGROUND AND OBJECTIVE: Open suturing (OSu) and mini-screw anchor (MsA) are two commonly used open disc repositioning surgeries for anterior disc displacement (ADD) of the temporomandibular joint (TMJ). This study assesses the differences in disc position stability (DPS) and condylar bone remodelling (CBR) between these two surgical procedures in a single centre. METHODS: A retrospective cohort study using MRI scans (pre-operation, 1 week and 12 months post-operation) of all patients who had open TMJ disc repositioning surgery from January 2016 to June 2021 at one centre through two surgical techniques (OSu and MsA) was performed. The predictor variable was technique (OSu and MsA). Outcome variables were DPS and CBR. During follow-up, DPS was rated as good, acceptable and poor, and CBR was graded as improved, unchanged, and degenerated. Multivariate analysis was used to compare the DPS and CBR at 12 months after adjusting five factors including age, sex, Wilkes stage, preoperative bone status (normal, mild/moderate abnormal) and the degree of disc repositioning (normal, overcorrected, and posteriorly repositioned). Relative risk (RR) for DPS and CBR was calculated by multivariate logistic regression. RESULTS: Three hundred eighty-five patients with 583 joints were included in the study. MRIs at 12 months showed that 514 joints (93.5%) had good DPS, and 344 joints (62.5%) had improved CBR. Multivariate analysis revealed that OSu had higher DPS (RR=2.95; 95% CI, 1.27-6.85) and better CBR (RR=1.58; 95% CI, 1.02-2.46) than MsA. Among the factors affecting DPS, females had better results than males (RR=2.63; 95% CI, 1.11-6.26) and overcorrected or posteriorly repositioned discs were more stable than normally repositioned discs (RR=5.84; 95% CI, 2.58-13.20). The improvement in CBR decreased with age increasing (RR=0.91; 95% CI, 0.89-0.93). Preoperative mild/moderate abnormal bone status had a higher probability of improved CBR compared to normal preoperative bone status (RR=2.60; 95% CI, 1.76-3.83). CONCLUSION: OSu had better DPS and CBR than MsA. Sex and the degree of disc repositioning impacted DPS, while age and preoperative bone status affected CBR.