Temporomandibular joint disc responses to installation and removal of the experimental malocclusion.

BACKGROUND: Aberrant occlusion and aging are two main risks for temporomandibular joint (TMJ) degeneration. OBJECTIVE: To assess the combined impact of occlusion and age on TMJ disc. METHODS: To avoid the confounding impact of gender, presently, 126 female C57BL/6J mice, 63 youngsters, 6-week old and 63 adults, 28-week old, were used. An experimental bilateral anterior crossbite (BAC) relation was created by installing metal tubes onto the mandibular incisors. Mice were sacrificed at 3, 7 and 11 weeks (n = 9). Additionally, the installed tubes were removed at 7 weeks in removal groups and the TMJs were sampled after another 4 weeks (n = 9). Disc changes were detected by histomorphology, immunohistochemistry, and western blot assays. RESULTS: Disc deformation was obvious in BAC groups. The typical change was hyperplasia at the posterior region of the disc where there was significant infiltration of inflammatory cells. Expressions of the inflammatory markers, including tumour necrosis factor-α and interleukin-1ß, and the catabolic markers, including fibronectin (FN), FN N-terminal fragments, and vascular endothelial growth factor-A, were all increased. The changes were more obvious in adults than in youngsters. Removal of BAC attenuated inflammatory and catabolic changes in the youngsters, but the inflammatory markers recovered little in the adults. CONCLUSION: TMJ disc responds to BAC by degeneration and inflammation, and respond to BAC removal by rehabilitation. Adult discs show severer degeneration responses to BAC and a lower level of anti-inflammatory capability to BAC removal than the youngster's discs. Animals cannot be equated with humans. The human disc response to occlusion changes worth further exploration.

Biomimetic Scaffolds for Regeneration of Temporomandibular Joint Disc: A Narrative Review.

Defects and dysfunctions of temporomandibular joint (TMJ) disc are responsible for the majority of TMJ diseases. Current treatments in this matter are usually short-term and only palliative, thus an alternative treatment that offers long-lasting repair is in great demand. In recent years great attempts have been made to prepare an ideal scaffold, which best resembles the native TMJ disc in characteristics such as mechanical, physical and biological properties. This narrative review focuses on developments of the recent ten years in fabrication of scaffolds using decellularized tissues, natural and synthetic biomaterials for regeneration of TMJ disc and compared their properties. PubMed and Google Scholar databases were searched using the following keywords ("TMJ" OR "temporomandibular joint" OR "TMD" OR "temporomandibular disease") AND ("scaffold" OR "hydrogels"). Randomized controlled trials, randomized clinical trials, case-controls, case reports, and animal studies were included. Comments, systematic reviews, meta-analyses, and non-English papers were excluded. The study concluded that hybrid scaffolds have exhibited favorable cell attachment and proliferation. Synthetic scaffolds have shown promise in providing better control over structural properties; however, additional processes are often required to provide biomimetic cell signaling. While there is still much to learn about the ideal scaffold for TMJ disc regeneration, both natural and synthetic scaffolds have shown promise in achieving the functional, structural, biological, and mechanical properties of a native TMJ disc.

Enhanced multistage deep learning for diagnosing anterior disc displacement in temporomandibular joint using magnetic resonance imaging.

OBJECTIVES: This study aimed to propose a new method for the automatic diagnosis of anterior disc displacement of the temporomandibular joint (TMJ) using magnetic resonance imaging (MRI) and deep learning. By employing a multistage approach, the factors affecting the final result can be easily identified and improved. METHODS: This study introduces a multistage automatic diagnostic technique using deep learning. This process involves segmenting the target from MR images, extracting distance parameters, and classifying the diagnosis into three classes. MRI exams of 368 TMJs from 204 patients were evaluated for anterior disc displacement. In the first stage, five algorithms were used for the semantic segmentation of the disc and condyle. In the second stage, 54 distance parameters were extracted from the segments. In the third stage, a rule-based decision model was developed to link the parameters with the expert diagnosis results. RESULTS: In the first stage, DeepLabV3+ showed the best result (95% Hausdorff distance, Dice coefficient, and sensitivity of 6.47 ± 7.22, 0.84 ± 0.07, and 0.84 ± 0.09, respectively). This study used the original MRI exams as input without preprocessing and showed high segmentation performance compared with that of previous studies. In the third stage, the combination of SegNet and a random forest model yielded an accuracy of 0.89 ± 0.06. CONCLUSIONS: An algorithm was developed to automatically diagnose TMJ-anterior disc displacement using MRI. Through a multistage approach, this algorithm facilitated the improvement of results and demonstrated high accuracy from more complex inputs. Furthermore, existing radiological knowledge was applied and validated.

Influence of examiner calibration on clinical and MRI diagnosis of temporomandibular joint disc displacement: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to verify the accuracy of clinical protocols for the diagnosis of disc displacement (DD) compared with MRI, considering examiners' calibration. METHODS: PubMed, Cochrane (Central), Scopus, Web of Science, LILACS, Embase, Science Direct, Google Scholar, and DANS EASY Archive databases were searched. Two reviewers independently screened and selected the studies. A meta-analysis was conducted using the R Statistical software. Results are shown using sensitivity and specificity, and 95% confidence intervals. RESULTS: Of the 20 studies included in the systematic review, only three were classified as low risk of bias. Seventeen studies were included in the meta-analysis. Compared to MRI, clinical protocols showed overall sensitivity and specificity of 0.75 (0.63-0.83) and 0.73 (0.59-0.84) for DD diagnosis, respectively. For DD with reduction, sensitivity was 0.64 (0.48-0.77) and specificity was 0.72 (0.48-0.87). For DD without reduction, sensitivity was 0.58 (0.39-0.74) and specificity 0.93 (0.83-0.97). Only 8 studies reported examiner calibration when performing clinical and/or MRI evaluation; nevertheless, calibration showed a tendency to improve the diagnosis of DD. CONCLUSION: The sensitivity and specificity of clinical protocols in the diagnosis of DD are slightly below the recommended values, as well as the studies lack calibration of clinical and MRI examiners. Examiner calibration seems to improve the diagnosis of DD.

The mechanics of tissue-engineered temporomandibular joint discs: Current status and prospects for enhancement.

The temporomandibular joint (TMJ) disc is an essential protective but vulnerable fibrocartilage. Their high mechanical strength is vital in absorbing loads, reducing friction, and protecting the condylar surface. Many diseases can lead to the destruction or degeneration of the mechanical function of the TMJ disc. Unfortunately, conservative treatment is ineffective in restoring the defective mechanical properties of the discs. Tissue engineering has been investigated as a promising alternative treatment approach to approximate the properties of native tissue. However, it is difficult for tissue-engineered discs to obtain sufficient mechanical properties. Several approaches have been proposed to improve the mechanical properties of tissue-engineered constructs. In this review, we summarized the mechanical properties of native TMJ discs and discussed the current mechanical testing methods. We then summarized the current advances in improving the mechanical properties of TMJ disc tissue-engineered constructs. Moreover, existing challenges and outbreak directions are discussed. This review assists future research in better understanding the mechanical properties of both native and tissue-engineered TMJ discs. It provides new insights into future mechanical property enhancement for TMJ disc tissue engineering.

Mesenchymal stem cells-derived exosomes alleviate temporomandibular joint disc degeneration in temporomandibular joint disorder.

Temporomandibular joint (TMJ) disorder (TMD) is a chronic progressive disease that is commonly seen in clinical settings. TMJ disc degeneration is an important manifestation of TMD, and further aggravates the progression of TMD. However, treatments on TMJ disc degeneration are very limited till now. In this study, we first observed the effects of bone marrow stem cells (BMSC) conditioned medium on functions of TMJ disc fibroblasts. Then BMSC-derived small extracellular vesicles (BMSC-EVs) were isolated and exposed to TMJ disc fibroblasts. RNA-sequencing was used to further investigate the mechanisms. BMSC-EVs were finally injected into a rat model with TMD. Results showed that in the transwell co-culture system, the medium derived from BMSC reduced inflammation and enhanced chondrogenesis in TMJ disc fibroblasts. BMSC-EVs promoted proliferation, migration, and chondrogenic differentiation of TMJ disc fibroblasts, and inhibited apoptosis and inflammatory responses. Local injection of BMSC-EVs into the TMD model alleviated TMJ disc degeneration. Therefore, BMSC-EVs were a potentially effective, sustainable and clinically translational-promising option for TMJ disc degeneration, and further reduce the progression of TMD.

Influence of feeding a soft diet on proteoglycan expression in rat temporomandibular joint discs.

OBJECTIVES: Extracellular matrix components play a significant role in maintaining tissue integrity and pathological processes of the temporomandibular joint (TMJ). This study aimed to evaluate the influence of a soft diet on the mRNA expression of proteoglycans and glycosaminoglycans (GAGs) linked to proteoglycan core proteins in rat TMJ discs. METHODS: Thirty 4-week-old male Wistar rats were assigned to one of two groups: a control group fed a regular pellet diet and a soft diet group fed a powdered diet for 4 weeks. The mRNA expression levels of 12 proteoglycans in TMJ discs were evaluated using real-time polymerase chain reaction (PCR). In addition, histomorphometric and biochemical analyses were performed to evaluate the thickness and deoxyribonucleic acid (DNA), GAG, and water content of the TMJ discs. RESULTS: The TMJ disc thickness in the anterior, intermediate, and posterior bands decreased significantly in the soft diet group. The GAG content decreased significantly in the soft-diet group, whereas no significant differences in DNA content or water content ratio were observed between the groups. Real-time PCR indicated that the expression levels of aggrecan, versican, biglycan, decorin, fibromodulin, lumican, and chondroadherin decreased in the soft diet group. The expression levels of all versican isoforms decreased in the soft diet group. CONCLUSIONS: These results indicate that the biomechanical environment of the TMJ caused by a soft diet is closely related to the expression of proteoglycans in TMJ discs, which may eventually increase the fragility of the TMJ discs.

Exercise therapy in postoperative patients with temporomandibular joint internal derangement: A systematic review.

OBJECTIVE: Postoperative patients with temporomandibular joint internal derangement (ID) often have problems such as limited mouth opening and pain. Exercise therapy can be advantageous for improving the recovery of patients following surgery. However, there is continuing discussion on the precise aspects of the exercise program, including the optimal timing, length, intensity, and use of assistive equipment. Hence, this study aimed to incorporate pre-existing exercise treatment regimens and investigate their impact. METHODS: Publications that detailed the clinical treatment of patients with temporomandibular joint ID who received postoperative exercise therapy interventions were included. Nine databases were searched until October 1st, 2023. The JBI critical appraisal tools were used to assess the methodological quality of the included studies. RESULTS: Five studies were finally included for subsequent analysis; two were randomised controlled studies, and three were quasi-experimental. Exercises suitable for such patients encompass vertical, transverse, and horizontal stretching, among which vertical stretch can be divided into active and passive movements. The start time ranged from the first to the fifth week after surgery, with a duration of 1-6 months. Although the data in the studies could not be integrated and further analysed, preliminary results showed that maximum mouth opening and pain in patients improved significantly. The therapeutic effect of combining three exercise methods was best and was related to patient compliance. CONCLUSION: Exercise therapy positively affects postoperative rehabilitation in patients with temporomandibular joint ID. It is proposed that targeted, comprehensive studies be conducted to provide a basis for designing more sophisticated exercise therapy regimens and further confirm its curative effect.

Arthrocentesis versus occlusal coverage splints in the management of disc displacement without reduction: a systematic review and meta-analysis.

Disc displacement without reduction (DDwoR) can cause pain and limitations in mouth opening, with a significant impact on function. The optimal management strategy for DDwoR is unclear. Treatments include conservative management such as mandibular manipulation, occlusal splints, and patient education/self-management, as well as arthrocentesis, which is a minimally invasive procedure. The aim of this systematic review and meta-analysis was to ascertain whether there is a role for arthrocentesis in the management of DDwoR. Studies analysing the outcomes pain and maximum mouth opening (MMO) in patients with DDwoR treated by arthrocentesis or occlusal coverage devices were eligible for inclusion. Following a database search, six studies with a total of 343 participants were found to be eligible for analysis (three prospective observational studies, one retrospective observational study, one non-randomized single-blind clinical trial, and one unblinded randomized clinical trial). When compared to occlusal coverage splints, arthrocentesis demonstrated a slight improvement in pain, although this was statistically non-significant (standardized mean difference (SMD) -0.50, 95% confidence interval (CI) -1.04 to 0.05, P = 0.07; I2 = 81%), and a significant improvement in MMO (SMD 0.79 mm, 95% CI 0.24-1.35 mm, P = 0.005; I2 = 79%). However, due to the significant heterogeneity between studies and the high risk of bias, along with the paucity of double-blind randomized controlled clinical trials, definitive conclusions cannot be drawn for this clinical question.

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.

Relationships between functional temporomandibular joint space and disc morphology, position, and condylar osseous condition in patients with temporomandibular disorder.

OBJECTIVE: To investigate the correlations between joint space and temporomandibular joint (TMJ) components and the compressive states of the disc and condyle subsequent to joint space changes. MATERIALS AND METHODS: A total of 240 TMJs were categorized according to disc morphology, disc position, and condylar osseous condition. The two-dimensional (2D) and three-dimensional (3D) measurements were compared. The functional joint space (FJS) and disc areas on closed- and open-mouth images (DA-C and DA-O) were also calculated, and the joint space was measured in five directions. Different groups of TMJ components were compared. A spring model was used to simulate the effect of condylar displacement on the disc and condyle. RESULTS: Disc morphology was strongly correlated with its position. The measurements were equivalent between 2D and 3D methods. DA-C and FJS differed significantly between groups. The DA-C to FJS ratio differed between the Class 2 and Class 3 groups and between disc displacement groups with and without reduction. Altered disc morphology and position were correlated with significant changes in joint space in the 60°, 90°, and 120° directions. Despite minor discrepancies among condylar osseous conditions, reduced joint space was correlated with bone destruction at the corresponding site. The spring model stimulation revealed that condylar displacement caused elevated stresses on the disc and condyle. CONCLUSIONS: Condylar displacement causes joint space alterations while exerting compressive pressure on both the disc and condyle. CLINICAL RELEVANCE: Proper condylar positioning within the fossa is recommended to ensure sufficient articular disc accommodation.

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.

Treatment of painful temporomandibular joint disc displacement without reduction: network meta-analysis of randomized clinical trials.

There is currently no consensus on the best treatment for painful temporomandibular disc displacement without reduction (DDwoR), and no network meta-analysis (NMA) of randomized clinical trials (RCTs) comparing all types of treatments for this condition has been conducted. The objective of this study was to compare and rank all treatments for DDwoR, including conservative treatments, occlusal splints, low-level laser therapy (LLLT), arthrocentesis (Arthro) alone, Arthro plus intra-articular injection (IAI) of platelet-rich plasma (PRP), Arthro plus IAI of hyaluronic acid (HA), Arthro with exercises, Arthro plus occlusal splints, and manipulative therapy. Outcome variables were pain intensity on a visual analogue scale (VAS) and maximum mouth opening (MMO, mm). The mean difference with 95% confidence interval was estimated using Stata software. The GRADE system was used to assess the certainty of the evidence. A total of 742 patients from 16 RCTs were included in the NMA. Both direct meta-analysis and NMA showed that Arthro with IAI of co-adjuvants provided better pain reduction in the short term (≤3 months) than Arthro alone. However, the quality of the evidence was very low. In the intermediate term, Arthro alone or combined with co-adjuvants provided better pain reduction than conservative treatment, but with low-quality evidence. Conservative treatment significantly increased MMO in the short term compared to other treatments. In conclusion, the results of this NMA suggest that arthrocentesis with intra-articular injection of adjuvant medications may be superior to conservative treatments in reducing pain intensity at long-term follow-up, while no significant differences were found for the MMO outcome. However, the quality of evidence was generally low to very low, and further RCTs are needed to confirm these findings.

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.

In vitro differentiation of human induced pluripotent stem cells into temporomandibular joint disc like cells.

Temporomandibular joint discs (TMJ discs) are unable to repair themselves in disease states, while induced stem cell differentiation is a common method to repair tissue defects. Nowadays, kinds of stem cells are attempted for tissue regeneration of TMJ disc, but these methods have several downsides, which limit their wide application. The proliferation and differentiation ability of human induced pluripotent stem cells (hiPSC) provides a new research direction for TMJ disc tissue regeneration. In this study, we investigated the feasibility of induced differentiation of hiPSC into TMJ disc cells in vitro and the differentiation efficiency of different methods to clarify the possibility and conditions of hiPSC application in TMJ disc tissue engineering. We collected sheep TMJ disc cells cultures for adding in hiPSC culture environment and treated hiPSC by both direct induction and Transwell co-culture for 7 days, 14 days and 21 days. The secretion of extracellular matrix in TMJ disc cells was detected by Sirius Red and Safranin O staining. Collagen Ⅰ and Collagen Ⅱ were qualitatively detected by immunohistochemical staining. The expression of extracellular matrix genes (type I collagen (COL1A1), type II collagen(COL2), glycosaminoglycan (GAG)), chondrogenic differentiation gene SOX9 and pluripotency gene OCT4 were detected by RT-qPCR. Our results showed that hiPSC had the ability to differentiate to TMJ disc cells by direct induction in TMJ disc cell culture medium and by Transwell co-culture method. The highest degree of differentiation was observed after 14 days of direct induction, while Transwell co-culture showed significant differentiation at different times and with different major directions. Meanwhile, Transwell co-culture not only differentiates hiPSC but also promotes the growth and proliferation of TMJ disc cells. Our study is valuable to investigate the possibility of differentiation of hiPSC toward TMJ disc cells and to determine the time of differentiation. It provides new ideas for the selection of seed cells for TMJ disc tissue engineering.

Arthroscopy versus arthrocentesis and versus conservative treatments for temporomandibular joint disorders: a systematic review with meta-analysis and trial sequential analysis.

The aim of this systematic review was to assess the efficacy of arthroscopy compared to arthrocentesis and to conservative treatments for temporomandibular joint disorders. Thirteen controlled studies on various patient outcomes were included after a systematic search in seven electronic databases. Meta-analyses were conducted separately for arthroscopic surgery (AS) and arthroscopic lysis and lavage (ALL), and short-term (<6 months), intermediate-term (6 months to 5 years), and long-term (≥5 years) follow-up periods were considered. No significant differences in pain reduction and complication rates were found between AS or ALL and arthrocentesis. Regarding improvement in maximum mouth opening (MMO), both AS at intermediate-term and ALL at short-term follow-up were equally efficient when compared to arthrocentesis. However, at intermediate-term follow-up, ALL was superior to arthrocentesis for MMO improvement (mean difference 4.9 mm, 95% confidence interval 2.7-7.1 mm). Trial sequential analysis supported the conclusion of the meta-analysis for MMO improvement for ALL versus arthrocentesis studies at intermediate-term follow-up, but not for the other meta-analyses. Insufficient evidence exists to draw conclusions regarding other patient outcomes or about comparisons between arthroscopy and conservative treatments. Due to the low quality of the primary studies, further research is warranted before final conclusions can be drawn regarding the management of temporomandibular joint disorders.

Assessment of temporomandibular joint disc position and skeletal stability after bimaxillary surgery.

PURPOSE: This study aimed to assess the correlation between temporomandibular joint (TMJ) disc position and skeletal stability and identify the cephalometric measurements associated with relapse after bimaxillary surgery. METHODS: The participants were 62 women with jaw deformities (124 joints) who underwent bimaxillary surgery. The TMJ disc position was classified into four types (anterior disc displacement (ADD), anterior, fully covered, and posterior) using magnetic resonance imaging, and cephalometric analysis was performed preoperatively and 1 week and 1 year postoperatively. The differences between pre- and 1-week postoperative values (T1) and 1-week and 1-year postoperative value (T2) were calculated for all cephalometric measurements. Moreover, the relationship between skeletal stability using cephalometric measurements, skeletal class, and TMJ disc position was analyzed. RESULTS: The participants included 28 patients in class II and 34 in class III. There was a significant difference in T2 in SNB between class II mandibular advancement cases and class III mandibular setback cases (P = 0.0001). In T2, in ramus inclination, there was a significant difference between the ADD and posterior types (P = 0.0371). Stepwise regression analysis revealed that T2 was significantly correlated with T1 for all measurements. However, the TMJ classification was not applied to all measurements. CONCLUSION: This study suggested that TMJ disc position, including ADD, could not affect skeletal stability, including the maxilla and distal segment after bimaxillary osteotomy, and short-term relapse could be related to the movement amount or angle change by surgery for all measurements.

Perforation of the temporomandibular joint disc: cadaveric anatomical study.

The aim of this human cadaveric study was to investigate the relationship between temporomandibular joint disc perforation and bony changes of the mandibular condyle. Overall, 135 cadaveric mandibles were used (69 male, 66 female; all White). Mean age at death was 78.7 years. Perforation of the disc was investigated. Differences in the area of the perforation according to the different types of bony change (erosion, flattening, osteophyte) were evaluated. Perforation of the disc was observed in 34.8% of all mandibles, occurring unilaterally in 53.2% of cases and bilaterally in 46.8%. The prevalence of perforation was 16.4% in cadavers <80 years old (67 heads) and 52.9% in those ≥80 years old (68 heads) (P < 0.001). Osteophyte formation was always identified along with other bony changes (21.7%) and never in isolation. The area of the perforation was significantly larger in the groups with bony changes (one, two, or three changes) than in the 'no bony change' group. The group with osteophyte formation showed a significantly larger perforated area than the group without osteophyte formation; likewise, the group with flattening showed a significantly larger perforated area than the group without flattening. Osteophytes and flattening are probably secondary bony changes that occur following disc perforation. Based on this study, disc perforation should be suspected when these findings are identified on imaging.

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.

Temporomandibular joint surgery: the past, present, and future.

Temporomandibular joint surgery for various pathological conditions and diseases affecting the integrity, mobility, and function of the joint has a long history. However, the greatest explosion of knowledge regarding the diagnosis and management of temporomandibular joint pain, pathology, and rehabilitation has occurred in the last 50 years. This review focuses on the incremental expansion of knowledge over time that led to the development of concepts that support our current surgical decisions and techniques, with the aim of identifying gaps in knowledge that require well-designed studies to move the field forward. Using this approach will allow an enhancement of our understanding of temporomandibular joint form and function, and enable focus to be placed on the evaluation, diagnosis, and non-surgical and surgical management strategies that are the most efficacious for our patients.