Relationship between appearance of a double contour on the mandibular condyle and the change in articular disc position after splint therapy

MiR-143-3p regulates chondrogenic differentiation of synovium derived mesenchymal stem cells under mechanical stress through the BMPR2-Smad signalling pathway by targeting BMPR2

BACKGROUND

Mesenchymal stem cells (MSCs) derived from the synovium, known as synovium mesenchymal stem cells (SMSCs), exhibit significant potential for articular cartilage regeneration owing to their capacity for chondrogenic differentiation. However, the microRNAs (miRNAs) governing this process and the associated mechanisms remain unclear. While mechanical stress positively influences chondrogenesis in MSCs, the miRNA-mediated response of SMSCs to mechanical stimuli is not well understood.

OBJECTIVE

This study explores the miRNA-driven mechano-transduction in SMSCs chondrogenesis under mechanical stress.

METHODS

The surface phenotype of SMSCs was analysed by flow cytometry. Chondrogenesis capacities of SMSCs were examined by Alcian blue staining. High throughput sequencing was used to screen mechano-sensitive miRNAs of SMSCs. The RNA expression level of COL2A1, ACAN, SOX9, BMPR2 and miR-143-3p of SMSCs were tested by quantitative real-time polymerase chain reaction (qRT-PCR). The interaction between miR-143-3p and TLR4 was confirmed by luciferase reporter assays. The protein expression levels of related genes were assessed by western blot.

RESULTS

High-throughput sequencing revealed a notable reduction in miR-143-3p levels in mechanically stressed SMSCs. Gain- or loss-of-function strategies introduced by lentivirus demonstrated that miR-143-3p overexpression hindered chondrogenic differentiation, whereas its knockdown promoted this process. Bioinformatics scrutiny and luciferase reporter assays pinpointed a potential binding site for miR-143-3p within the 3'-UTR of bone morphogenetic protein receptor type 2 (BMPR2). MiR-143-3p overexpression decreased BMPR2 expression and phosphorylated Smad1, 5 and 8 levels, while its inhibition activated BMPR2-Smad pathway.

CONCLUSION

This study elucidated that miR-143-3p negatively regulates SMSCs chondrogenic differentiation through the BMPR2-Smad pathway under mechanical tensile stress. The direct targeting of BMPR2 by miR-143-3p established a novel dimension to our understanding of mechano-transduction mechanism during SMSC chondrogenesis. This understanding is crucial for advancing strategies in articular cartilage regeneration.

Effect of occlusal stabilisation splint with or without arthroscopic disc repositioning on condylar bone remodelling in adolescent patients

The aim of this study was to investigate the treatment effects of a stabilisation splint (SS) with and without arthroscopic disc repositioning (ADR) on condylar bone remodelling in adolescent patients with anterior disc displacement without reduction (ADDwoR). Cone beam computed tomography and magnetic resonance imaging were used to analyse condylar bone remodelling, condyle position, and disc position. Twenty-two temporomandibular joints of 14 patients who underwent ADR (age range 12-20 years; mean follow-up 12.5 ± 7.8 months) and 21 temporomandibular joints of 14 patients who did not undergo ADR (age range 13-20 years; mean follow-up 11.1 ± 5.1 months) were included. The change in bone volume (P < 0.001), rate of bone volume change (P < 0.001), and change in condyle height (P = 0.031) were significantly greater in patients with ADR than in those without ADR. The changes in posterior joint space (P = 0.013), superior joint space (P = 0.020), and ratio of condyle sagittal position (P = 0.013) were significantly greater in patients with ADR than in those without ADR. All discs in patients who underwent ADR and one disc in those who did not undergo ADR were backward repositioned. In conclusion, in adolescent patients with ADDwoR, ADR with SS therapy achieved better condyle and disc position than SS therapy alone, and also induced bone generation.

Step-back anterior repositioning splint retraction for temporomandibular joint disc displacement with reduction in adult patients

BACKGROUND

Anterior repositioning splint (ARS) is used to treat temporomandibular joint (TMJ) disc displacement with reduction (DDwR). However, high recurrence rate remains a problem especially in patients with unstable occlusions.

OBJECTIVE

This study optimised standard ARS therapy and proposed a step-back ARS retraction (SAR) method in adult patients with DDwR.

METHODS

Dental examinations and magnetic resonance imaging of TMJ were obtained before treatment (T0), 1 to 3 months (T1), 3 to 6 months (T2) and 6 to 12 months (T3) during treatment in 48 adults (average age 27.1 ± 5.7 years). After 3 months of basic ARS wearing, personalised treatment for patients with normal disc-condyle relationship was prescribed depending on bilaminar zone adaptations and severity of molar openbite. SAR which required sequential ARS wearing was designed for patients with deep overbite/overjet until retrodiscal tissue adaptations and stable occlusions were achieved.

RESULTS

The maximum interincisal opening was increased from 44.3 ± 6.9 to 45.3 ± 6.3 mm (p < .01), and joint pain was alleviated after ARS treatment. The overall success rate of ARS wearing was 92.1% (58/63) featured by a recaptured disc. Fifteen patients who underwent SAR therapy all showed bilaminar zone adaptations in the end, and one patient had positive condylar bone remodelling.

CONCLUSIONS

ARS treatment could improve mouth opening and joint symptoms in adult DDwR patients. SAR method was suitable for treating DDwR patients with deep overbite and overjet and improved retrodiscal tissue adaptations and condylar bone remodelling.

Assessing the Efficacy of Anterior Repositioning Splints in the Management of Temporomandibular Disc Displacement: A Systematic Review and Meta-Analysis

Disc displacement (DD) occurs when the cushioning disc of the temporomandibular joint (TMJ), situated between the jawbone and the skull, is out of position. The condition can be of two kinds: disc displacement with reduction (ddwr) and disc displacement without reduction (ddwor). The present systematic review was undertaken to assess the efficacy of anterior repositioning splints (ARS) for ddwr and ddwor. Three online databases were searched for relevant studies using MeSH keywords and Boolean operators. Initial searches of the databases extracted 552 records. Twelve studies equally representing ARS with ddwr and ddwor were selected. No clear difference could be assessed regarding ARS usage in both conditions. The outcome assessed was the improvement in TMJ symptoms. The results suggested that both ddwr and ddwor were effective in improving temporomandibular joint (TMJ) symptoms in patients who received ARS therapy. Efficacy levels ranged from 71-83% and 50-95% for ARS in ddwr and ddwor, respectively; odds ratio (OR) values ranging from 0.30 and 0.36 were obtained for ARS in both therapies, respectively, indicating similar performance levels. Both ddwr and ddwor respond well to the use of ARS; however, more clinical trials are needed to ascertain and validate the role of ARS as a treatment modality in this regard.

Arthroscopic Disk Repositioning After Failed Open Disk Repositioning

PURPOSE

Open disk repositioning has been long achieving excellent functional and stability outcomes. However, still remains some relapses for whom a second open surgery is often challenging. This study aimed to evaluate the effectiveness of arthroscopic disk reposition as an alternative surgery for unsuccessful cases of anterior disk displacement (ADD) after an initial open disk repositioning.

MATERIALS AND METHODS

This retrospective study included all patients who underwent secondary arthroscopy for disk repositioning of the relapsed ADD after an initial open surgery between January 2012 to June 2017. The redo arthroscopic disk repositioning and suturing procedure was the primary predictor input variable in this study. Outcome evaluation was based on both clinical (visual analog scale and maximal interincisal opening) and magnetic resonance imaging data.

RESULTS

Twenty-seven joints fulfilling the inclusion criteria were included. A significant improvement was detected at 24-month postoperatively compared with the baseline visual analog scale. The maximal interincisal opening showed a statistical improvement from 25.07 mm preoperatively to 38.44 mm at 24-month postoperatively. Twenty-six joints maintained a stable disk position with only 1 joint relapsed to ADD without reduction.

CONCLUSION

Arthroscopic disk reposition and suturing technique is a reliable and effective repeat surgery after failed initial open disk repositioning for management of ADD.

An Overview of Anterior Repositioning Splint Therapy for Disc Displacement-related Temporomandibular Disorders

Anterior repositioning splint (ARS) therapy is considered one of the most effective therapies for treating disc displacement-related temporomandibular disorders (TMDs), which account for a large proportion of TMD cases. Owing to the wide application of this therapy, the exact mechanism of remission has increasingly drawn attention. Given that practitioners have different views on ARS therapy, its indications are broadened, and operating methods diverged. This review attempts to provide an overview of ARS therapy and helps practitioners establish indications and suitable operating methods. Representative views in the past 10 years were summarised, and conclusions were drawn as follows: The mechanism of ARS therapy is mainly attributed to internal derangement correction, improvement of stress distribution and recently reported joint remodeling. It has an evident effect in the short term, and the most prevalent operating methods are protruding the mandible to the edge-to-edge position and wearing the ARS for 24 hours daily for 3-6 months. However, long-term stability is not optimal, and thus indications should be selected carefully. Notably, most of the clinical studies in this field are case analyses with low-quality evidence. Well-designed RCTs are required to further validate relevant theories.

Condylar repair and regeneration in adolescents/young adults with early-stage degenerative temporomandibular joint disease: A randomised controlled study

BACKGROUND

Anterior repositioning splint (ARS) can facilitate regenerative condylar remodelling.

OBJECTIVE

To determine the effect of ARS on osseous condylar changes in adolescents/young adults with early-stage degenerative joint disease (DJD).

METHODS

Sixty-nine patients with early-stage temporomandibular joint (TMJ) DJD based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and cone beam computed tomography (CBCT) imaging were recruited and randomly allocated to two treatment groups: (a) conservative therapy with ARS and (b) conservative therapy without ARS. Subjects with acute TMJ closed-lock had their displaced discs physically reduced by mandibular manipulation prior to ARS therapy. Clinical and CBCT data of 59 patients (86.4% females, mean age 17.95 ± 4.53 years, 67 joints) were attained pre- and at 6 or 12 months post-treatment. Osseous changes after treatment were categorised into (a) progressed, (b) unchanged, (c) repaired (remodelled without new bone formation) and (d) regenerated (remodelled with new bone formation). Statistical analysis including chi-square test, independent samples t test or Mann-Whitney U test was conducted.

RESULTS

About 85.5% of patients (59/69) completed the study, with 28 subjects (32 joints) in the splint group and 31 (35 joints) in the control group. The occurrence of condylar repair and regeneration was significantly higher with ARS (78.1%/[25/32] of joints) when compared to control group (48.6%/[17/35]) (P < 0.05). Moreover, condylar regeneration was exclusively observed in 50%/(16/32) of joints with ARS. For the 14 joints in splint group that received physical TMJ closed-lock reduction, 85.7%/(12/14) exhibited condylar regeneration. The splint group (3.1%/[1/32]) also had significantly lower incidence of progressive TMJ degeneration than the control (37.1%/[13/35]) (P < 0.001).

CONCLUSION

Condylar repair and regeneration in early-stage TMJ DJD are possible, and ideal spatial disc-condyle relationship appears important. The possibility of restoring TMJ form/structure by ARS therapy presents an attractive area of new basic science and clinical research (Bone defect repair in early osteoarthrosis of temporomandibular joint by joint distraction therapy: A randomized controlled trial/ChiCTR-TRC-14005172).

A controversy with respect to occlusion

There are very little controversies on occlusion in healthy individuals, where centric relation is regarded as the criterion for assessing the present occlusion and also for establishing a new occlusal relationship between the upper and the lower jaws. On the other hand, the occlusal position in patients with deformed condyles still remains to be clarified. In this review, the effectiveness and limits of centric relation in these patients are discussed. In addition, the muscle induced occlusal positions, such as the muscular position and the terminal positions of habitual closing movements, are suggested as a substitution for centric relation. Finally, the importance of a stable intercuspal position, where the habitual closing movements terminate without any premature tooth contact, is emphasized.

Bayesian belief network analysis applied to determine the progression of temporomandibular disorders using MRI

OBJECTIVES

This study investigated the applicability of a Bayesian belief network (BBN) to MR images to diagnose temporomandibular disorders (TMDs). Our aim was to determine the progression of TMDs, focusing on how each finding affects the other.

METHODS

We selected 1.5-T MRI findings (33 variables) and diagnoses (bone changes and disc displacement) of patients with TMD from 2007 to 2008. There were a total of 295 cases with 590 sides of temporomandibular joints (TMJs). The data were modified according to the research diagnostic criteria of TMD. We compared the accuracy of the BBN using 11 algorithms (necessary path condition, path condition, greedy search-and-score with Bayesian information criterion, Chow-Liu tree, Rebane-Pearl poly tree, tree augmented naïve Bayes model, maximum log likelihood, Akaike information criterion, minimum description length, K2 and C4.5), a multiple regression analysis and an artificial neural network using resubstitution validation and 10-fold cross-validation.

RESULTS

There were 191 TMJs (32.4%) with bone changes and 340 (57.6%) with articular disc displacement. The BBN path condition algorithm using resubstitution validation and 10-fold cross-validation was >99% accurate. However, the main advantage of a BBN is that it can represent the causal relationships between different findings and assign conditional probabilities, which can then be used to interpret the progression of TMD.

CONCLUSIONS

Osteoarthritic bone changes progressed from condyle to articular fossa and finally to mandibular bone contours. Disc displacement was directly related to severe bone changes. Early bone changes were not directly related to disc displacement. TMJ functional factors (condylar translation, bony space and disc form) and age mediated between bone changes and disc displacement.

[Condylar hyperplasia: qualitative and quantitative study of temporomandibular joints remodeling before and after condylectomy]

PURPOSE

This retrospective study aimed to evaluate bone remodeling of temporo-mandibular joints (TMJ) using computed tomography (CT) before and after condylectomy for condylar hyperplasia.

MATERIAL AND METHOD

TMJ bone remodeling was studied by comparing the pre and postoperative CT scan of ten patients. Qualitative evaluation was performed by two-dimensional analysis. Three-dimensional analysis superimpositions were done after digital condylar units isolation. Condylar volume modifications were measured and compared on both sides. Lastly, before and after surgery, we studied the radio-clinic correlations.

RESULTS

After surgery, all the operated condyles developed a new cortical bone. We noticed also a thickening of the glenoid fossa. Surgical condylectomy leaded to a 43.5% volume reduction on the operated side and 2.14% on the controlateral side. On the controlateral side, most of abnormalities seen preoperatively disappeared after surgery. For two patients, the condylar resection took away over 80% of the initial volume. For these patients, we observed major radiologic modifications on the controlateral TMJ associated with symptoms of dysfunction. These problems did not worsen their quality of life.

CONCLUSION

Both TMJ presented with bone remodelling after condylectomy. In condylar hyperplasia, condylectomy provides orthopaedic results on dysmorphia and removal of the pathological prechondroblastic zone. In the future, an earlier detection of this pathology may help the surgeon to treat in childhood. This would limit surgical excision and would avoid important dysmorphia.

Alterations of the Temporomandibular Joint on Magnetic Resonance Imaging according to Growth and Development in Schoolchildren

The paper explains the alterations of the temporomandibular joint (TMJ) visualized by magnetic resonance imaging (MRI) according to the growth and development of schoolchildren. Appearance and disappearance of a "double contour-like structure" (DCLS) of the mandibular condyle on MRI according to the growth and development of schoolchildren were demonstrated. In addition, possible constituents of DCLS and the significance of detection of DCLS on MRI were also speculated. The relationship between red marrow and yellow marrow in the articular eminence of temporal bone, the disappearance of DCLS, and alterations of the mandibular condyle have been elucidated.

Relation between disk/condyle incoordination and joint morphological changes: a retrospective study on 268 TMJs

OBJECTIVE

The relation between disk/condyle incoordination and temporomandibular joint (TMJ) morphological changes is incompletely known. To address the research purpose, the investigators designed a cohort study of 268 TMJs. MRIs were evaluated.

STUDY DESIGN

A series of morphological parameters were investigated regarding disk, condyle, tuber, interarticular space, and muscles. Pearson chi square was the statistical method used.

RESULTS

Disk incoordination is statistically associated with morphological changes of condyle and tuber. No association was detected regarding morphological changes of disk, interarticular space, muscles, and pain. Reported data have shown that disk and condyle incoordination are related to morphological changes of TMJ surfaces (i.e., both condyle and tuber). The functional changes (i.e., pain, interarticular space reduction or enlargement, presence of fat in muscles, and disk derangements) are not associated with disk and condyle incoordination.

CONCLUSION

The reported data do not allow determination of which is the first cause (i.e., the disk/condyle incoordination or morphological changes of TMJ surfaces). Additional studies are needed to address this last question.