The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept

Effect of Anterior Disc Displacement and Estrogen Deficiency on Rabbit Mandibular Condyle

OBJECTIVE

In this study, we aimed to establish an experimental model of idiopathic condylar resorption by combining surgically induced anterior disc displacement and estrogen deficiency in growing rabbits. This study aimed to investigate the individual and combined effects of these factors on condylar resorption.

MATERIALS AND METHODS

Seventeen female Japanese White rabbits were divided into four groups: control, ovariectomy, anterior disc displacement surgery, and combination of ovariectomy and anterior disc displacement surgery. Micro-computed tomography and histological evaluations were performed to analyze changes in the trabecular bone structure and cartilage thickness of the condyle.

RESULTS

The combined group exhibited the most significant changes in trabecular bone parameters, including the lowest bone volume per tissue volume and trabecular number and the highest trabecular separation and spacing. Histologically, the fibrous layer thinned and the hypertrophic layer thickened in the anterior and central parts of the condyle in the anterior disc displacement and combined groups. The Modified Mankin Score indicated the highest level of degenerative change in the combined group.

CONCLUSION

The combination of surgically induced anterior disc displacement and estrogen deficiency in growing rabbits effectively modeled idiopathic condylar resorption, demonstrating the synergistic impact of disc displacement and estrogen deficiency on condylar resorption. This model provides valuable insight into the pathogenesis of idiopathic condylar resorption.

Intramuscular Botulinum Toxin as an Adjunct to Arthrocentesis with Viscosupplementation in Temporomandibular Disorders: A Proof-of-Concept Case-Control Investigation

BACKGROUND

The reduction in joint load is a potential beneficial factor in managing osteoarthritis of the temporomandibular joint (TMJ). This paper aims to compare the effectiveness of the intramuscular injection of botulinum toxin (BTX-A) as an adjunct to TMJ arthrocentesis plus viscosupplementation with arthrocentesis plus viscosupplementation alone in the management of TMJ osteoarthritis.

METHODS

A pilot clinical retrospective study examined TMJ osteoarthritis treatments. Patients were divided into two groups: Group A received BTX-A injections and arthrocentesis with viscosupplementation, while Group B received only arthrocentesis with viscosupplementation. The study assessed outcomes based on mouth opening (MO), pain at rest (PR), pain at mastication (PF), and masticatory efficiency (ME) at various time points (baseline (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4)) up to 2 months after treatment.

RESULTS

The study included two groups, each with five patients. Group A received five weekly sessions of arthrocentesis plus viscosupplementation and a single BTX-A injection during the first arthrocentesis appointment. Group B underwent the five-session protocol of arthrocentesis plus viscosupplementation alone. MO, PF, PR, and ME improved quickly in T2 in both groups, but the improvement was of greater importance over the following weeks and lasted longer in Group A.

CONCLUSIONS

Arthrocentesis with viscosupplementation associated with BTX-A was found to be more effective than arthrocentesis alone in improving clinical outcomes. This suggests that patients with TMJ osteoarthritis and myofascial pain may benefit from reduced muscle tone and joint load.

Is there a superiority between arthrocentesis and stabilizing occlusal splint for the treatment of anterior disc displacement with reduction and intermittent block and anterior disc displacement without reduction in TMJ? Randomized clinical trial

INTRODUCTION

Anterior displacement of the temporomandibular joint (TMJ) disc is a disorder in which the articular disc is dislocated from its correct position relative to the mandibular condyle and mandibular fossa. Traditionally, the initial treatment of disc displacements involves various conservative measures, including the use of a stabilizing interocclusal splint. However, in cases where there is associated limited mouth opening, as in the case of anterior disc displacement with reduction and intermittent block (ADDwRIB), and anterior disc displacement without reduction (ADDw/oR), arthrocentesis has been suggested as another modality of initial treatment due to its faster effect in preventing disease progression to a more advanced stage, as well as reducing the chances of pain chronification and central sensitization.

OBJECTIVES

This study aimed to analyze whether there is a preponderance in efficacy between treatments with a stabilizing interocclusal splint or arthrocentesis in these patients.

METHODS

A randomized, prospective, longitudinal clinical trial was conducted. The sample was obtained by convenience, between June 2021 and January 2023. Twenty-four patients with diagnoses of ADDwRIB and ADDw/oR were included. The diagnosis and clinical evaluations followed the DC/TMD criteria, and TMJ MRI was performed. Patients were randomly allocated to 2 treatment groups. Group 1 (n = 13): stabilizing interocclusal splint. Group 2 (n = 11): arthrocentesis. Patients were evaluated after 1, 2, 3, and 6 months for clinical parameters of pain, functionality, and psychosocial status.

RESULTS

Both treatments were effective in reducing pain levels, with no statistically significant differences. Group 1 showed significantly greater mouth-opening levels compared to Group 2 (P = .041).

CONCLUSION

Both groups showed significant improvements in various parameters evaluated throughout the study, indicating they are equally effective in pain control and most functional and quality of life parameters. However, the stabilizing interocclusal splint treatment was superior in restoring mouth opening.

Salivary Biomarkers and Temporomandibular Disorders: A Systematic Review conducted according to PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions

BACKGROUND

The present review aimed to investigate the association between salivary biomarkers and temporomandibular disorders (TMD). TMD is a multifactorial condition characterised by pain and dysfunction in the temporomandibular joint (TMJ) and surrounding structures. Salivary biomarkers have emerged as potential diagnostic tools due to their non-invasiveness and easy accessibility. However, the literature on salivary biomarkers in relation to TMD is limited and inconsistent.

METHODS

Electronic databases of Pubmed, Embase, Web of Science, Scopus, Cochrane Library, PsychINFO, CINAHL and Medline were searched using specific search terms and Boolean operators. The search was limited to articles published in English that assessed salivary biomarkers in individuals diagnosed with TMD. Two reviewers independently screened the articles and extracted data. ROB-2 was used to assess the risk of bias.

RESULTS

Eleven clinical papers met the inclusion criteria and were included in the review. The findings provided consistent evidence of a clear association between salivary biomarkers and TMD. Various biomarkers, including cortisol, IL-1, glutamate and several others, were assessed. Some studies reported higher levels of cortisol and IL-1 in TMD patients, indicating potential involvement in stress and inflammation. Glutamate levels were found to be elevated, suggesting a role in pain modulation. Other biomarkers also showed alterations in TMD patients compared to controls: CONCLUSION: The findings from the included studies suggest that salivary biomarkers may play a role in TMD pathophysiology. Though a definitive conclusion can be drawn regarding the specific salivary biomarkers and their association with TMD, the results must be interpreted with caution considering the heterogeneity of the biomarkers assessed. Further research with larger sample sizes, standardised methodology and rigorous study designs is needed to elucidate the role of salivary biomarkers in TMD.

Temporomandibular joint disc repositioning and occlusal splint for adolescents with skeletal class II malocclusion: a single-center, randomized, open-label trial

BACKGROUND

Temporomandibular joint (TMJ) disc repositioning through open suturing (OSu) is a new disc repositioning method. Its result for adolescents with condylar resorption and dentofacial deformities combined with and without postoperative occlusal splints (POS) has not been well studied.

OBJECTIVE

This study was to evaluate and compare the effects of OSu with and without POS in the treatment of TMJ anterior disc displacement without reduction (ADDwoR) in adolescent skeletal Class II malocclusion.

METHODS

A total of 60 adolescents with bilateral ADDwoR were enrolled in this study. They were randomly allocated into two groups: OSu with and without POS. Magnetic resonance imaging (MRI) and lateral cephalometric radiographs were used to measure changes in condylar height and the degree of skeletal Class II malocclusion from before operation and at 12 months postoperatively. Changes in these indicators were compared within and between the two groups.

RESULTS

After OSu, both groups exhibited significant improvements in condylar height and occlusion at the end of 12 months follow-up (P < 0.05). The group of OSu with POS had significantly more new bone formation (2.83 ± 0.75 mm vs. 1.42 ± 0.81 mm, P < 0.001) and improvement in dentofacial deformity than the group of OSu only (P < 0.05). The new bone height was significantly correlated with POS (P < 0.001), the changes of SNB (P = 0.018), overjet (P = 0.012), and Wits appraisal (P < 0.001).

CONCLUSION

These findings indicated that OSu can effectively stimulate condylar regeneration and improve skeletal Class II malocclusion in adolescents with bilateral ADDwoR. The results are better when combined with POS.

TRIAL REGISTRATION

This trial was prospectively registered on the chictr.org.cn registry with ID: ChiCTR1900021821 on 11/03/2019.

Pharmacological Management of Orofacial Pain

Orofacial pain is a category of complex disorders, including musculoskeletal, neuropathic and neurovascular disorders, that greatly affect the quality of life of the patient. These disorders are within the fields of dentistry and medicine and management can be challenging, requiring a referral to an orofacial pain specialist, essential for adequate evaluation, diagnosis, and care. Management is specific to the diagnosis and a treatment plan is developed with diverse pharmacological and non-pharmacological modalities. The pharmacological management of orofacial pain encompasses a vast array of medication classes and approaches. This includes anti-inflammatory drugs, muscle relaxants, anticonvulsants, antidepressants, and anesthetics. In addition, as adjunct therapy, different injections can be integrated into the management plan depending on the diagnosis and needs. These include trigger point injections, temporomandibular joint (TMJ) injections, and neurotoxin injections with botulinum toxin and nerve blocks. Multidisciplinary management is key for optimal care. New and safer therapeutic targets exclusively for the management of orofacial pain disorders are needed to offer better care for this patient population.

Temporomandibular joint arthrocentesis: a single-center experience and review of the literature

BACKGROUND

The aim of this paper was to report our experience and to review the literature of arthrocentesis focusing on protocols and results.

METHODS

Arthrocentesis with supplemental hyaluronic acid was performed in patients with TMDs between January 2017 and December 2020 at the Division of Maxillofacial Surgery. The maximum interincisal opening (MIO) and pain score were recorded preoperatively (T0), 2 months postoperatively (T1), and 6 months postoperatively (T2). A literature search was performed to analyze the same parameters in patients with TMDs. Patient demographic, characteristics and treatment protocols used were also recorded.

RESULTS

This retrospective analysis enrolled 45 patients. Twenty-two patients (20 females, 2 males) with mean age of 37.13 years with internal derangement were included in study group A. Study group B included 23 patients with degenerative joint disease (19 females and 4 males) with mean age of 55.73 years. The outcomes trend of MIO and pain during the follow-up period showed a gradual improvement. Fifty articles meeting the proposed scientific criteria were selected for the literature revision. A range of clinical and procedural variables were analyzed by grouping the studies into two broad categories based on the diagnosis of TMD.

CONCLUSIONS

Based on our experience and on the basis of the most accredited scientific studies in the literature, intra-articular injections of HA are beneficial for the improvement of the pain and/or functional symptoms of TMDs.

Biomechanics and Derangements of the Temporomandibular Joint

The human temporomandibular joint, is a ginglymo-arthrodial joint. The articular disk serves as a fibrous, viscoelastic structure that allows force distribution and smooth movement of the joint in its normal arrangement during mandibular movements. Most studies suggest that in the normal disk position the posterior band is located at the 12'o clock position within the glenoid fossa in the closed mouth posture. When the biomechanics of the joint is altered, the disk may be displaced creating an abnormal relationship between the disk, condyle, and the eminence that is often referred to as an internal derangement. This article reviews the various presentations of internal derangements.

Correlation between the main clinical, imaging, and arthroscopy findings in patients with temporomandibular disorders

The purpose of this work was to prospectively correlate the most characteristic clinical symptoms of temporomandibular disorders, such as pain and limitation of mouth opening, with the findings of magnetic resonance imaging (disc position, degenerative changes, and effusion) and arthroscopy findings (roofing, synovitis, chondromalacia, adhesions, and perforations). These examinations were performed in 298 patients diagnosed with internal derangement refractory to conservative treatment. The mean age of the patients was 38.59 years; 92.6% were female. The t-test and one-way analysis of variance (ANOVA) were used to correlate the findings. Significant relationships were found between pain and disc displacement without reduction (P = 0.033) and effusion (P = 0.003) on MRI, coinciding with correlations between pain and roofing of 0-25% (P = 0.016) and synovitis (P = 0.001) on arthroscopy. A significant relationship was also observed between mouth opening limitation and the presence of osteoarthrosis (P = 0.018) on MRI, and between mouth opening limitation and synovitis (P = 0.022), chondromalacia (P = 0.002), and adhesions (P < 0.001) on arthroscopy. All of these findings were observed in patients with a poor initial clinical situation, which highlights the considerable potential of correlating these data with imaging and arthroscopy findings.

Oral and maxillofacial literature from Middle East: a bibliometric analysis and list of top-100 most cited articles

OBJECTIVES

The aim of this work is to perform a bibliometric analysis on Middle Eastern oral and maxillofacial surgery through years and to compare the data with previous studies. A list of the top 100 most cited articles was generated.

METHODS

A Pubmed bibliographic search for literature journals specialized in oral and maxillofacial surgery in the Middle East was performed. A graphic representation of authorship and keywords was created with VOSviewer. Mendeley and Microsoft Excel were used for tabulation and data visualization. A list of the top 100 most cited articles was created using Web of Science. Some statistical tests were performed with a 95% confidence interval, which was considered significant.

RESULTS

A total of 6,536 articles were retrieved in fifteen selected oral and maxillofacial journals. A moderate correlation between number of publications and total population (R = 0.6052), low correlation with area (R = 0.302291), and a negligible correlation with the Human Development Index (HDI) were found (R = 0.1747). A disparity can be seen in the number of publications by country, leaded by Turkey (46.30%), Israel and Iran (13.68% each). The more common studied topic was oral surgery (25.77%), maxillofacial trauma (16.13%) and oral pathology (10.25%).

CONCLUSIONS

A useful list of the top 100 most cited articles on oral and maxillofacial surgery from Middle East has been created. Middle East publications on oral and maxillofacial surgery can be considered high quality (IF = 1.879). Some issues on performing an adequate selecting of MeSH keywords were discussed.

Arthroscopic osteoplasty of the medial and anteromedial wall of temporomandibular joint: surgical technique and anatomical considerations

The anterior displacement of the articular disc is the most frequent cause of pathological alterations in the TMJ. Although it is an extremely common pathology, there is no certainty about the aetiopathogenesis of this disease. The main aim of the present report is to describe new anatomical findings that could help clarifying the aetiopathogenesis of this disease and determine a typology of treatment based on the cause of the disease. All the operative records of patients who underwent arthroscopic osteoplasty of the medial TMJ wall in our centre from January 2021 to September 2021 were reviewed and analysed to identify specific anatomical features observed in every procedure. Fifty-two joints were included for analysis in this study. Twenty-two joints were classified as Wilkes stages II-III and 30 as Wilkes stages IV-V. The most common complication observed in our sample was the dysaesthesias found in the temporal and preauricular regions. Other complications observed were frontal branch paresis (n = 2), intraoperative bleeding (n = 1), and postoperative malocclusion (n = 1). The compression of the superior head of pterygoid lateral muscle (SPLM) on the medial bony wall and the consequent muscle atrophy could be key for the aetiology of the anterior TMJ disc displacement. Therapeutic actions on the osseous and muscular component in this anatomical area could improve the outcomes of patients affected by TMJ internal derangement. A meticulous dissection of the fascia of the superior fascicle of the lateral pterygoid muscle allows a remodelling of the bone surfaces with minimal complications.

Athrocentesis: What, When, and Why?

The introduction of temporomandibular joint (TMJ) arthroscopy by Onishi in 1970 (results published in 1975 and 1980) opened a new modality for TMJ treatment. The efficiency of arthroscopic lavage and lysis led in the 1990s to its simplification: TMJ arthrocentesis. Always associated with load control, physiotherapy, and elimination of any occlusal hazards, arthrocentesis, a simple procedure, entails less expensive and more available tools and is performed under local anesthesia. Although lacking direct visual inspection of the joint structures, it has become quite popular. Arthrocentesis is most efficient in localized joint pain and limited joint movements such as closed lock, anchored disc phenomenon, osteoarthritis, and various inflammatory diseases. In clicking joint, the results are somewhat controversial. The efficiency of arthrocentesis elicited many enquiries that led to the study and a better understanding of joint function and dysfunction and the actual role of disc location. The release of closed lock without disc repositioning was quite surprising; it improved our understanding of the pathogenesis of closed lock and led to the discovery of the anchored disc phenomenon. This was followed by the awareness of the joint-lubrication system and, in turn, alternative suggestions for the pathogenesis of TMJ disc displacement with and without reduction, open lock, and osteoarthritis, and ultimately by the development of an effective bio-lubricant. Awareness of the role of joint overloading led to the development of an interocclusal appliance that reduces intraarticular pressure; it has become a "must" support for arthrocentesis and any surgical intervention. In our view, arthrocentesis is the definitive indication of the need for surgical intervention and, therefore, should be the first in the cascade of interventions in TMJ disorders.

940 nm diode laser induced differentiation of human adipose derived stem cells to temporomandibular joint disc cells

Background

Temporomandibular disorder (TMD) refers to a group of disorders that affect temporomandibular joint (TMJ) and its associated muscles with very limited treatment options. Stem cell research is emerging as one of the promising fields in the treatment of degenerative diseases. The ability of human adipose derived stem cells to differentiate into many cell types is driving special interest in several disease management strategies. Photobiomodulation has enhanced the role of these stem cells through their ability to promote cell proliferation and differentiation. Hence, this study examined the differentiation potential of human adipose derived stem cells (ADSCs) into fibroblasts and chondrocytes using a 940 nm diode laser for possible TMD therapy.

Materials and methods

ADSCs were cultured at different seeding densities and for different time intervals. After irradiation at 24, 48, 72 h, 1, 2 and 3 weeks, ADSC viability and morphological changes were assessed in groups with and without basic fibroblast growth factor. Additionally, the level of adenosine triphosphate (ATP) in the cells was also recorded. The differentiated fibroblasts and chondrocytes were characterized with flow cytometry and immunofluorescence techniques, at 1- and 2-weeks post-irradiation.

Results

Increased ATP proliferation and cell viability above 90% were observed in all post-irradiation experimental groups. Post irradiation results from flow cytometry and immunofluorescence at 1- and 2‐weeks confirmed the expression of chondrogenic and fibroblastic cell surface markers.

Conclusion

This study describes stimulatory techniques utilized to differentiate ADSCs into fibroblastic and chondrogenic phenotypes using diode lasers at 940 nm. The study proposes a new treatment model for patients with degenerative disc diseases of the TMJ. The study will offer new possibilities in tissue engineering and TMJ disc management through photobiomodulation of ADSCs using a 940 nm diode laser.

Expressions of parathyroid hormone-related protein (PTHrP) and parathyroid hormone receptor-1 (PTH1R) in the condylar cartilage of temporomandibular joint modulated by occlusal elevation

Background/purpose

Parathyroid hormone-related protein (PTHrP) is an important regulatory factor in the growth, development and remodeling of bone or cartilage, and acts through its sole receptor, parathyroid hormone receptor-1 (PTH1R). The present study aimed to research the expression changes of PTHrP, PTH1R and other relevant factors in condylar cartilage during the progress of temporomandibular joint osteoarthritis (TMJOA).

Materials and methods

The animal model of TMJOA was constructed by the "resin-modified method", and Sprague Dawley (SD) rats were euthanized at 2 weeks, 4 weeks, 6 weeks and 8 weeks after occlusal elevation. The histological changes of condylar cartilage were observed by X-ray, hematoxylin-eosin (HE) and safranine O-fast green (SO-FG) staining. The expressions of PTHrP, PTH1R, Ki67, Collagen II (Col II), Collagen X (Col X) and Caspase 3 in each group were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC).

Results

TMJOA progression was time-dependent. In the experimental group, PTHrP expression was unimodal with a peak at 4 weeks, but PTH1R expression showed a decreasing trend. From 2 weeks to 8 weeks in the experimental group, Col X expression rather than Caspase 3 expression was negatively related to PTHrP's, which has no positive relation to Ki67 or Col II. These results demonstrated abnormal occlusal load may be an important pathogenic factor of TMJOA.

Conclusion

It may be one of the reasons of TMJOA progression that PTHrP can't play an effective role due to the low expression of PTH1R. PTHrP may be a direct factor regulating the hypertrophic differentiation of chondrocytes, but it does not directly regulate the proliferation and apoptosis of chondrocytes, and the realization of both regulatory effects may depend on the inhibition of hypertrophic differentiation.

Effects of patient education on the oral behavior of patients with temporomandibular degenerative joint disease: a prospective case series study

OBJECTIVE

To evaluate the effects of patient education and related factors on oral behaviors (OBs) in patients with temporomandibular joint degenerative diseases.

METHODS

Sixty-three patients were included. Temporomandibular joint specialists conducted clinical examinations, provided patient education, and administered the Oral Behavior Checklist (OBC) questionnaire at baseline. Patients were followed up at 6 months.

RESULTS

Eight OBs showed a high incidence among patients. At the 6-month follow-up, the incidence of 6 of the OBs decreased, all of which were high incidence OBs. The frequency of 9 OBs decreased, of which 8 were high incidence OBs. The average OBC score decreased from 22.97 ± 9.30 to 17.90 ± 9.28. Age, education level, and original OBC score had a significant effect on OB improvement.

CONCLUSION

Patient education and the corresponding treatment are conducive to OB improvement. The related factors affecting the improvement in patients' OBs were age, education level, and OB severity.

Action of Hyaluronic Acid as a Damage-Associated Molecular Pattern Molecule and Its Function on the Treatment of Temporomandibular Disorders

The temporomandibular joint is responsible for fundamental functions. However, mechanical overload or microtraumas can cause temporomandibular disorders (TMD). In addition to external factors, it is known that these conditions are involved in complex biological mechanisms, such as activation of the immune system, activation of the inflammatory process, and degradation of extracellular matrix (ECM) components. The ECM is a non-cellular three-dimensional macromolecular network; its most studied components is hyaluronic acid (HA). HA is naturally found in many tissues, and most of it has a high molecular weight. HA has attributed an essential role in the viscoelastic properties of the synovial fluid and other tissues. Additionally, it has been shown that HA molecules can contribute to other mechanisms in the processes of injury and healing. It has been speculated that the degradation product of high molecular weight HA in healthy tissues during injury, a low molecular weight HA, may act as damage-associated molecular patterns (DAMPs). DAMPs are multifunctional and structurally diverse molecules that play critical intracellular roles in the absence of injury or infection. However, after cellular damage or stress, these molecules promote the activation of the immune response. Fragments from the degradation of HA can also act as immune response activators. Low molecular weight HA would have the ability to act as a pro-inflammatory marker, promoting the activation and maturation of dendritic cells, the release of pro-inflammatory cytokines such as interleukin 1 beta (IL-1β), and tumor necrosis factor α (TNF-α). It also increases the expression of chemokines and cell proliferation. Many of the pro-inflammatory effects of low molecular weight HA are attributed to its interactions with the activation of toll-like receptors (TLRs 2 and 4). In contrast, the high molecular weight HA found in healthy tissues would act as an anti-inflammatory, inhibiting cell growth and differentiation, decreasing the production of inflammatory cytokines, and reducing phagocytosis by macrophages. These anti-inflammatory effects are mainly attributed to the interaction of high-weight HA with the CD44 receptor. In this study, we review the action of the HA as a DAMP and its functions on pain control, more specifically in orofacial origin (e.g., TMD).

General Characteristics, Biomedical and Dental Application, and Usage of Chitosan in the Treatment of Temporomandibular Joint Disorders: A Narrative Review

The aim of this narrative review was to present research investigating chitosan, including its general characteristics, properties, and medical and dental applications, and finally to present the current state of knowledge regarding the efficacy of chitosan in the treatment of temporomandibular disorders (TMDs) based on the literature. The PICO approach was used for the literature search strategy. The PubMed database was analyzed with the following keywords: (“chitosan”[MeSH Terms] OR “chitosan”[All Fields] OR “chitosans”[All Fields] OR “chitosan s”[All Fields] OR “chitosane”[All Fields]) AND (“temporomandibular joint”[MeSH Terms] OR (“tem-poromandibular”[All Fields] AND “joint”[All Fields]) OR “temporomandibular joint”[All Fields] OR (“temporomandibular”[All Fields] AND “joints”[All Fields]) OR “temporo-mandibular joints”[All Fields]). After screening 8 results, 5 studies were included in this review. Chitosan presents many biological properties and therefore it can be widely used in several branches of medicine and dentistry. Chitosan promotes wound healing, helps to control bleeding, and is used in wound dressings, such as sutures and artificial skin. Apart from its antibacterial property, chitosan has many other properties, such as antifungal, mucoadhesive, anti-inflammatory, analgesic, antioxidant, antihyperglycemic, and antitumoral properties. Further clinical studies assessing the efficacy of chitosan in the treatment of TMD are required. According to only one clinical study, chitosan was effective in the treatment of TMD; however, better clinical results were obtained with platelet-rich plasma.

Finite element analysis of various thickness occlusal stabilization splint therapy on unilateral temporomandibular joint anterior disc displacement without reduction

INTRODUCTION

Occlusal stabilization splint is the most common treatment modality for temporomandibular joint disorders, but the optimal thickness is still uncertain. This study investigated the effect of the occlusal splint with different thicknesses on the stress distribution of the temporomandibular joint.

METHODS

Cone-beam computed tomography and magnetic resonance images were used to reconstruct the maxillofacial and disc, and the unilateral anterior disc displacement without reduction was established manually as the basic model. Occlusal splint with 5 different thickness levels (2, 3, 4, 5, and 6 mm) was added to the basic model as the study models. The displacement and stress distribution of the disc were evaluated.

RESULTS

The maximum von Mises stress of the condylar cartilage was the largest on the affected side, whereas the maximum von Mises stress of the disc was the largest on the unaffected side. The disc stress on the affected side was mainly distributed on the posterior zone and the intermediate zone for the unaffected side. The maximum von Mises stress of the bilaminar region on the affected side was greater than the unaffected side. The stress of the disc and bilaminar region was the lowest on the affected side in the 2 mm model. The disc displacement on the affected side gradually increased, whereas, on the unaffected side, it fluctuated.

CONCLUSIONS

These results showed that occlusal stabilization splint could decrease the stress of disc and bilaminar region, and 2 mm was considered the optimal thickness for the treatment of unilateral temporomandibular joint anterior disc displacement without reduction.

Condylar erosion is predictive of painful closed lock of the temporomandibular joint: a magnetic resonance imaging study

Background

To assess whether magnetic resonance imaging (MRI) findings of condylar erosion (CE) are predictive of a specific clinical diagnosis of painful closed lock of the temporomandibular joint (TMJ), and to determine the strength of association between CE and types of internal derangement (ID).

Methods

Based upon sample size estimation, this retrospective paired-design study involved 62 patients, aged between 18 and 67 years. Inclusion criteria were the presence of a unilateral clinical diagnosis of arthralgia coexisting with disk displacement without reduction (‘AR and DDwoR/wLO’), assigned according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I, and the absence of signs and symptoms of TMJ pain and dysfunction on the contralateral TMJ side. Bilateral sagittal and coronal MR images were obtained to establish the prevalence of CE and TMJ ID types of disk displacement with (DDR) and without reduction (DDNR). Logistic regression analysis was used to compute odds ratios for CE and ID types. Confounding variables adjusted for were age, sex, time since pain onset, pain intensity, and type of ID.

Results

In the regression analysis, the MRI items of DDR (p = 0.533) and DDNR (p = 0.204) dropped out as nonsignificant in the diagnostic clinical ‘AR and DDwoR/wLO’ group. Significant increases in the risk of ‘AR and DDwoR’ occurred with CE (3.1:1 odds ratio; p = 0.026). The presence of CE was significantly related to DDNR (adjusted OR = 43.9; p <  0.001).

Conclusions

The data suggest CE as a dominant factor in the definition of painful closed lock of the TMJ, support the view that joint locking needs to be considered as a frequent symptom of osteoarthritis, and emphasize a strong association between the MRI items of CE and DDNR.

Osteoarthritis of the temporomandibular joint: A review of aetiology and pathogenesis

The aim of this review was to assess the level of evidence for genetic, biological, and functional predictive and predisposing factors for end-stage temporomandibular joint arthritis within the published literature. A comprehensive review based upon PRISMA guidelines was performed from all literature relevant to the topic. Case series and animal studies were included given the rare nature of the disease and goal of finding root-cause predictive factors. Clinical and radiographic measures were used specifically to identify factors which may have contributed to disease onset and progression. A total of 249 abstracts were identified based on search terms of major databases. After application of exclusion and inclusion criteria, 63 full-text articles were included in the analysis of this paper. There were few factors that could be reliably used to predict end-stage temporomandibular joint disease. Limited evidence is available to adequately predict end-stage temporomandibular joint osteoarthritis. No descriptive process exists that explains how and why this process can occur in younger adults. A better understanding of the aetiology and pathogenesis of TMJ-OA may lead to prevention and more effective management strategies that may reduce the need for drastic surgical intervention, particularly in young adults.

Asporin levels in patients with temporomandibular joint disorders

BACKGROUND

Understanding the pathogenesis of temporomandibular joint disorder (TMD) is important for diagnosis and treatment planning. Thus, biochemical analysis is usually used for the detection of tissue damage.

OBJECTIVE

In this study, we aimed to investigate the serum asporin levels in patients with TMD.

METHODS

Our study was planned to be performed on 43 healthy individuals (control group) without any joint problems and 43 patients with temporomandibular joint internal derangement (TMJ-ID; patients group) according to the Wilkes classification (stages 3, 4 and 5). Serum asporin levels were determined by the enzyme-linked immunosorbent assay (ELISA) method and compared between groups. Asporin levels were analysed according to the demographic and clinical characteristics of the patients, and the differences between them were demonstrated.

RESULTS

Asporin levels were found to be significantly increased in the patients group compared to control group (p = .0303). The age and gender distributions of the samples in the control and patients groups were homogeneous, and there was no statistically significant difference between the groups. In addition, while there was no significant change in asporin levels in females in the patients group compared with the control group, the asporin levels were significantly increased in males in the patients group (p = .0403).

CONCLUSIONS

Consequently, asporin seems to be an important biomarker in the pathobiology of TMJ-ID as it is significantly upregulated in these patients.

A logistic analysis prediction model of TMJ condylar erosion in patients with TMJ arthralgia

BACKGROUND

In terms of diagnostic and therapeutic management, clinicians should adequately address the frequent aspects of temporomandibular joint (TMJ) osteoarthritis (OA) associated with disk displacement. Condylar erosion (CE) is considered an inflammatory subset of OA and is regarded as a sign of progressive OA changes potentially contributing to changes in dentofacial morphology or limited mandibular growth. The purpose of this study was to establish a risk prediction model of CE by a multivariate logistic regression analysis to predict the individual risk of CE in TMJ arthralgia. It was hypothesized that there was a closer association between CE and magnetic resonance imaging (MRI) indicators.

METHODS

This retrospective paired-design study enrolled 124 consecutive TMJ pain patients and analyzed the clinical and TMJ-related MRI data in predicting CE. TMJ pain patients were categorized according to the research diagnostic criteria for temporomandibular disorders (RDC/TMD) Axis I protocol. Each patient underwent MRI examination of both TMJs, 1-7 days following clinical examination.

RESULTS

In the univariate analysis analyses, 9 influencing factors were related to CE, of which the following 4 as predictors determined the binary multivariate logistic regression model: missing posterior teeth (odds ratio [OR] = 1.42; P = 0.018), RDC/TMD of arthralgia coexistant with disk displacement without reduction with limited opening (DDwoR/wLO) (OR = 3.30, P = 0.007), MRI finding of disk displacement without reduction (OR = 10.96, P < 0.001), and MRI finding of bone marrow edema (OR = 11.97, P < 0.001). The model had statistical significance (chi-square = 148.239, Nagelkerke R square = 0.612, P < 0.001). Out of the TMJs, 83.9% were correctly predicted to be CE cases or Non-CE cases with a sensitivity of 81.4% and a specificity of 85.2%. The area under the receiver operating characteristic curve was 0.916.

CONCLUSION

The established prediction model using the risk factors of TMJ arthralgia may be useful for predicting the risk of CE. The data suggest MRI indicators as dominant factors in the definition of CE. Further research is needed to improve the model, and confirm the validity and reliability of the model.

An International Survey on Temporomandibular Joint Surgeon's Implementation and Management of Discectomy in Treating Temporomandibular Joint Internal Derangement

PURPOSE

To survey temporomandibular joint (TMJ) surgeons to determine current practice trends and perceptions regarding the role of discectomy for the treatment of TMJ internal derangements.

METHODS

An anonymous 5-part web-based survey was sent to TMJ surgeons. The survey was created and distributed, and the data were collected with the University of Michigan Qualtrics platform. Responses were compared based on operative volume, tendency to replace the disc, and likelihood of requiring temporomandibular joint replacement (TJR) after discectomy. Spearman correlations were used to test statistically significant differences. Domain-level analyses were also performed by summarizing items into 3 domain scores. Analyses were performed in SAS V9.4 (SAS Institute Inc., Cary, NC, USA).

RESULTS

Fifty-nine surgeons (33.9%) completed the survey. Discectomy was not considered to be a useful procedure by 85% of respondents, and 74% would not consider discectomy as a first surgical option. Most would consider discectomy (64%) before alloplastic total joint replacement. Discectomy was preferred over discopexy for the management of anterior disc displacement with reduction by high volume surgeons (89%), but most (72%) did not feel that discectomy was beneficial over arthroscopy in the treatment of anterior disc displacement without reduction and concomitant degenerative bony changes. In managing symptomatic disc perforation, 66% agreed that discectomy is the procedure of choice and 49% felt that interpositional tissue is indicated in most cases after discectomy. Respondents who reported fewer re-operations requiring alloplastic TJR after discectomy had, on average, more positive perceptions of discectomy on the benefits domain (P = .03), better than alternatives domain (P = .03), and fewer concerns on the perceived adverse effects domain (P = .03).

CONCLUSIONS

TMJ surgeons do not employ TMJ discectomy in most cases of TMJ internal derangement. However, discectomy is considered useful in cases of disc perforation or for persistent symptomatic disc displacement without reduction, in an attempt to avoid alloplastic TJR. Common adverse effects included joint noises and osteoarthrosis, and the use of interpositional disc replacement tissue did not alter the incidence of adverse effects or complications reported.

Transitioning to chronic temporomandibular disorder pain: A combination of patient vulnerabilities and iatrogenesis

Background

Based on a variety of studies conducted in recent years, some of the factors that might contribute to the negative treatment responses of some TMD patients have been elucidated.

Methods

This paper describes known vulnerability factors that make individuals susceptible to developing temporomandibular disorders (TMDs), as well as those that contribute to the perpetuation of such problems. In addition, the topic of iatrogenesis is discussed as a major contributor to the negative outcomes that can be seen in this field.

Results

At the patient level, anatomical, psychosocial and genetic factors may contribute to individual vulnerability. The anatomy and pathophysiology of muscles, joints, disc and nerves may all be involved in predisposing to TMD symptoms, especially when the patients have pain elsewhere in the body. Among the psychosocial factors, some features may be elucidated by the DC/TMD axis II, while others (eg illness behaviour, Munchausen syndrome, lack of acceptance of non‐mechanical approaches) require careful evaluation by trained clinicians. Genetic predisposition to first onset TMDs and to chronification of symptoms has been identified for individuals with certain psychological traits, presence of comorbid conditions and certain abnormal clinical manifestations. Regarding iatrogenesis, sins of omission may influence the clinical picture, with the main ones being misdiagnosis and undertreatment. Joint repositioning strategies, occlusal modifications, abuse of oral appliances, use of diagnostic technologies, nocebo effect and complications with intracapsular treatments are the most frequent sins of commission that may contribute to chronification of TMDs. The patients who present with massive occlusal and jaw repositioning changes combined with persistent severe orofacial pain are not a rarity within TMD and orofacial pain canters; these patients are the most difficult ones to manage because of this horrific combination of negative factors.

Conclusions

The information presented in this paper will help clinicians to understand better why some individuals develop temporomandibular disorders, why some of them will progress to becoming chronic patients, and what the appropriate responses may be.

Imaging, histopathological degree of degeneration and clinical findings - Do these correlate in patients with temporomandibular joint disorders

The gold standard for temporomandibular joint imaging is magnetic resonance imaging, although there are still pathological findings that cannot be seen in MRI but in surgery and the subsequent histological analysis only. The main goal of this investigation was to validate the MRI score used by histopathological findings as well as clinical findings. In this retrospective study 39 patients were included; 38 of which underwent unilateral and 1 underwent bilateral discectomy. MRI findings were graded according to the score by Wurm. Histopathological analysis was performed in hematoxylin-eosin staining and graded in accordance with the scores by Krenn and by Leonardi. For valuation of preoperative pain values of the temporomandibular joint operated on the numeric rating scale was utilized. Correlations were verified by Spearman-Rho. The MRI scores on average showed significantly lower scores for the discs of the operated temporomandibular joint than for the discs of the non-operated side(p<.01). No significant correlations between MRI findings, histopathological findings and pain intensities could be observed. Thus unsuspicious morphology of the TMJ and the articular disc in MRI is no guarantee for the absence of cartilage-degeneration. Further investigations utilizing T2 cartilage mapping could possibly show better correlations between the temporomandibular joint's degree of degeneration and imaging results.

Initiation and progression of dental-stimulated temporomandibular joints osteoarthritis

Temporomandibular joint (TMJ), a site that is often impacted by osteoarthritis (OA), is biomechanically linked with dental occlusion. Tissue responses in TMJ condyle to biomechanical stimulation could be investigated by intervention of the dental occlusion in animals. Unilateral anterior crossbite, an experimental malocclusion, has been demonstrated to induce TMJ-OA lesions, showing primarily as enhanced cartilage calcification and subchondral cortical bone formation at the osteochondral interface, causing the osteochondral interface thickening and stiffening. The changed interface would worsen the local biomechanical environment. At the cartilage side, the matrix degenerates. In the case of insufficient restoration of the matrix, the cells in the deep zone flow into the ones undergoing autophagy, apoptosis, and terminal differentiation while the cells in the superficial zone are promoted to differentiate to supply the loss of the deep zone cells. At the meantime, the bone marrow stromal cells are stimulated to bone formation in the subchondral cortical region which is uncoupled with the sites of the osteoclast-mediated resorption process that is predominantly observed at the subchondral trabecular bone region. Overall, the thickening and stiffening osteochondral interface, due greatly to the enhanced endochondral ossification in deep zone cartilage, should be a central pathological process that links with cartilage decay and subchondral bone remodelling in OA joints. The residual chondrocytes locating in the cartilage superficial zone have the progenitor-like qualities that can proliferate, and also differentiate into the deep zone chondrocytes, thus should be critical in progression and rehabilitation of TMJ-OA.

Do patient-reported outcome measures correlate with clinical follow-up after arthroscopic treatment of internal derangement of the temporomandibular joint?

INTRODUCTION

Arthroscopic treatment of the temporomandibular joint (TMJ) has traditionally been evaluated with clinical measurements. Additional recordings of patient reported outcome measures (PROM) is expected to make the evaluation more complete. The aim of the study was to evaluate if PROM correlates with clinical follow-up measures after arthroscopic treatment of internal derangement of the TMJ.

MATERIAL AND METHODS

Patients with temporomandibular dysfunction (TMD), treated with arthroscopic lysis and lavage of the TMJ, were followed with a PROM questionnaire; Jaw Functional Limitation Scale 20 (JFLS-20) and a review of patient medical records. Out of 239 patients treated, 134 were eligible for inclusion to the study.

RESULTS

91 subjects, 21 males and 70 females, with mean age 42.6 years completed the follow-up. The JFLS-20 mean score was 25.43 (range: 0-148). A correlation was found between JFLS and mouth opening. The JFLS-20 score was decreased by 1.48 (p = 0.0001) for ever millimeter larger mouth opening and with 1.16 (p = 0.001) for every gained millimeter of mouth opening after arthroscopic treatment of the TMJ. The mean maximal mouth opening was 38.43 mm preoperatively (15 to 75 mm) compared to 42.19 mm postoperatively (range: 21-75 mm). A total of 80 subjects with TMD associated pain preoperatively was reduced to 25 postoperatively (p = 0.0001).

DISCUSSION

Advantageous treatment effect with arthroscopic lysis and lavage was presented. The outcome of the JFLS-20 questionnaire indicates a correlation with the clinical findings. Future studies will focus on larger cohorts and using PROM with a case-control setting.

The immunoregulatory role of p21 in the development of the temporomandibular joint-osteoarthritis

Objective

We aimed to identify the immunoregulatory role of the cyclin‐dependent kinase inhibitor p21 in the homeostasis of mandibular condylar cartilage affected by mechanical stress.

Materials and methods

Ten C57BL/6 wild‐type (WT) and ten p21^−/− mice aged 8 weeks were divided into the untreated and treated groups. In the treated groups, mechanical stress was applied to the temporomandibular joint (TMJ) through forced mouth opening for 3 hr/day for 7 days. The dissected TMJs were assessed using micro‐CT, histology, and immunohistochemistry.

Results

Treated p21^−/− condyles with mechanical stress revealed more severe subchondral bone destruction, with thinner cartilage layers and smaller proteoglycan area relative to treated WT condyles; untreated WT and p21^−/− condyles had smoother surfaces. Immunohistochemistry revealed significant increases in the numbers of caspase‐3, interleukin‐1β, matrix metalloprotease (MMP)‐9, and MMP‐13 positive cells, and few aggrecan positive cells, in treated p21^−/− than in treated WT samples. Moreover, the number of TUNEL positive cells markedly increased in p21^−/− condyles affected by mechanical stress.

Conclusions

Our findings indicate that p21 in chondrocytes contributes to regulate matrix synthesis via the control ofm aggrecan and MMP‐13 expression under mechanical stress. Thus, p21 might regulate the pathogenesis of osteoarthritis in the TMJ.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis of the temporomandibular joint: A review

Loading is indispensable for the growth, development, and maintenance of joint tissues, including mandibular condylar cartilage, but excessive loading or reduced host adaptive capacity can considerably damage the temporomandibular joint (TMJ), leading to temporomandibular joint osteoarthritis (TMJ-OA). TMJ-OA, associated with other pathological conditions and aging processes, is a highly degenerative disease affecting the articular cartilage. Many treatment modalities for TMJ-OA have been developed. Traditional clinical treatment includes mainly nonsurgical options, such as occlusal splints. However, non-invasive therapy does not achieve joint tissue repair and regeneration. Growing evidence suggests that low-intensity pulsed ultrasound (LIPUS) accelerates bone fracture healing and regeneration, as well as having extraordinary effects in terms of soft tissue repair and regeneration. The latter have received much attention, and various studies have been performed to evaluate the potential role of LIPUS in tissue regeneration including that applied to articular cartilage. The present article provides an overview of the status of LIPUS stimulation used to prevent the onset and progression of TMJ-OA and enhance the tissue regeneration of mandibular condylar cartilage. The etiology and management of TMJ-OA are explained briefly, animal models of TMJ-OA are described, and the effectiveness of LIPUS on cell metabolism and tissue regeneration in the TMJ is discussed.

Photobiomodulation and Stem Cell Therapy for Temporomandibular Joint Disc Disorders

Background: Temporomandibular disorder (TMD) refers to a group of disorders affecting the temporomandibular joint (TMJ) and its related muscles. The two commonly used treatment modalities for TMD are occlusal splint therapy and relaxation therapy. Neither comprises definitive treatment. Objective: The objective of this review was to report updated information on photobiomodulation and stem cells, as an alternative treatment for the degenerative TMJ disc as a part of TMJ disorders. Materials and methods: With only a few research studies reported till date, this review also proposes the mechanism of laser irradiation on inflammatory mediators to treat TMD. Results: Photobiomodulation of stem cells with and without scaffolds could be used indirectly or directly as modulation of degenerative changes of the TMJ disc. Conclusions: The need for a distinct shift of the research margin in this field of dentistry is evident, specifically regarding the application of photobiomodulation and stem cells for tissue engineering of the TMJ disc.

A clinical-based protocol of diagnosis of temporomandibular joint open lock and treatment with arthrocentesis

PURPOSE

Arthrocentesis of the temporomandibular joint (TMJ) is a minimally invasive surgical procedure that provides good clinical results such as the improvement of jaw movements. It also helps to balance the synovial liquid viscosity and relieve TMJ pain by the washout of inflammatory components from the upper compartment. The purpose of this study is to report a case series of patients submitted to a clinical-based protocol of diagnosis of TMJ joint open lock and treatment with arthrocentesis.

MATERIAL AND METHODS

Patients suffering from a recurrent unilateral open lock of the TMJ were submitted to one arthrocentesis of the affected TMJ and all of them reported that the open lock was caused by daily stomatognathic activities. To decide the arthrocentesis as the initial treatment of these patients, the authors followed a rational protocol of diagnosis.

RESULTS

Ten patients were included in the present study. No complications occurred during arthrocentesis. Immediately, 1 week, 1 month, and 6 months after arthrocentesis, patients did not suffer from open lock or disc click anymore. They also reported no more pain because it was strictly related to the disc click.

CONCLUSIONS

All patients of the present study improved from the open lock and disc click of the affected TMJ for 6 months after arthrocentesis. The clinical-based protocol of diagnosis of TMJ open lock reported in the present study, followed by the treatment with arthrocentesis is a reasonable, low-cost, and safe method to treat patients with the acute open lock.

Finite elements analysis of the temporomandibular joint disc in patients with intra-articular disorders

Background

Intra-articular disorders (ID) or anterior and/or medial displacement of the temporomandibular joint disorder (TMJ) disc are the most common form of TMJ dysfunction (TMD). TMD causes changes in the friction coefficient during TMJ movement. Herein, we provided a three-dimensional (3D) finite-elements model (FEM) including the maxilla, disc, and mandible and evaluated the stress distribution with different friction coefficient.

Methods

Fourteen volunteers without TMD and 20 patients with MRI-diagnosed TMD were selected. CT and MRI data were collected to build the 3D FEA model of the mandible and TMJ disc. Stress distribution with different friction coefficient was measured.

Result

In the normal model, stress distribution on the TMJ disc was 2.07 ± 0.17, 1.49 ± 0.14, and 1.41 ± 0.14 MPa with 0.001, 0.3, and 0.4 friction coefficient, respectively. In the TMD model, stress distribution was 3.87 ± 0.15, 7.23 ± 0.22, and 7.77 ± 0.19 MPa respectively.

Conclusion

When the friction coefficient of the side with anterior displacement increased, stress on the disc, condyle and mandible of the opposite side increased. Simultaneously, stress values of the disc, condyle and mandible were higher than those of the normal lateral joint.

Does Incidence of Temporomandibular Disc Displacement With and Without Reduction Show Similarity According to MRI Results?

Purpose

The aim of this study is to assess MRI reports of the patients and to provide retrospective analysis by conducting detailed evaluation of temporomandibular disc position.

Patients and Methods

MRI images of 259 patients from 2008 to 2017 were reviewed retrospectively. Existence of disc displacement in joint with and without reduction, existence of effusion in joint gap, arthritis, degenerative changes in joints and limitation of movement of joint and anatomic characteristics were evaluated.

Results

One hundred and seventeen (45.2%) of the patients had healthy joint connection bilaterally. Anterior disc displacement was observed in 101 (38.9%) of the patients. The number of the patients having disc displacement with reduction was 50 (19.3%) and without reduction was 51 (19.6%) similarly.

Conclusion

The incidence of anterior disc displacement with or without reduction was similar; besides this, the majority of the patients diagnosed with anterior disc displacement were unilateral.

Prospective study to evaluate the influence of joint washing and the use of hyaluronic acid on 111 arthrocentesis

BACKGROUND

Temporomandibular dysfunction is a generic term that covers a large number of clinical problems affecting not only temporomandibular joint but also the masticatory musculature and related structures. Arthrocentesis is used in patients with joint pathology in which conservative treatment has failed.

METHODS

A prospective, observational, analytical cohort study has been carried out to evaluate the results of 111 arthrocentesis. We have performed an inferential statistics study between the variables: improvement of pain and improvement in the oral opening with the variables and access joint, washing joint, hyaluronic acid infiltration, and type of joint pathology.

RESULTS

Joint washing and intra-articular hyaluronic acid injection significantly improved the pain at 1-week, 1-month, and 3-month postarthrocentesis, although this improvement was limited in time, at 6 months, joint washing and hyaluronic acid infiltration are no longer significant. Only the joint access (p = 0.014) and the type of joint pathology (p = 0.028) are significant.

CONCLUSIONS

The effectiveness of joint access in the arthrocentesis at 6 months is high, although less than at 1-month and 3-month postarthrocentesis. The type of joint pathology is another important factor. Patients with degenerative pathology worsen the most after 6-month postarthrocentesis. Arthrocentesis could avoid the evolution of acute pathology.

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).

Stribeck Curve Analysis of Temporomandibular Joint Condylar Cartilage and Disc

Temporomandibular joint (TMJ) diseases such as osteoarthritis and disc displacement have no permanent treatment options, but lubrication therapies, used in other joints, could be an effective alternative. However, the healthy TMJ contains fibrocartilage, not hyaline cartilage as is found in other joints. As such, the effect of lubrication therapies in the TMJ is unknown. Additionally, only a few studies have characterized the friction coefficient of the healthy TMJ. Like other cartilaginous tissues, the TMJ condyles and discs are subject to changes in friction coefficient due to fluid pressurization. In addition, the friction coefficient of the TMJ is affected by the sliding direction and anatomic location. However, these previous findings have not been able to identify how all 3 of these parameters (anatomic location, sliding direction, and fluid pressurization) influence changes in friction coefficient. This study used Stribeck curves to identify differences in the friction coefficients of TMJ condyles and discs based on anatomic location, sliding direction, and amount of fluid pressurization (friction mode). Friction coefficients were measured using a cartilage on glass tribometer. Both TMJ condyle and disc friction coefficients were well described by Stribeck curves. These curves changed based on anatomic location, but very few differences in friction coefficients were observed based on sliding direction. TMJ condyles had similar boundary mode and elastoviscous mode friction coefficients to the TMJ disc, and both were lower than hyaline cartilage in other joints. The observed differences here indicate that the surface characteristics of each anatomic region cause differences in friction coefficients.

Analysis of the Correlation between Morphology and Kinematics of Anteriorly Displaced TMJ Discs Using Cine-MRI and ARCUSdigma Systems

Background:

Studies of mandibular movement trajectories have provided a good understanding of the motion of the condyle but little information on the geometric relationships of the disc because they have not related the movements to anatomic structures.

Objective:

This study investigated the morphology and kinematic characteristics of the Temporomandibular Joint (TMJ) using Cine-MRI and ARCUSdigma systems.

Methods:

For this study population, preliminary clinical diagnoses were asymptomatic in 15 cases, unilateral anterior disc displacement with reduction (ADDWR) in 17 cases, and unilateral Anterior Disc Displacement Without Reduction (ADDWoR) in 14 cases. Patients were investigated with Cine-MRI and ARCUSdigma systems during physiological opening and closing of the mouth.

Results:

In these groups, there were 13 healthy subjects, 19 patients with unilateral ADDWR and 14 patients with unilateral ADDWoR classified by Cine-MRI. (1) To assess morphology by MRI, disc deformities were evaluated as follows: biplanar, rounded, thickening in the posterior band, lengthened and folded. (2) The opening trajectory for healthy subjects was close to the closing trajectory. Conversely, the incisal and condylar trajectories during opening and closing were obviously bounced, deviated or shortened in the ADDWR and ADDWoR groups. The pathway of the kinematic axis was not parallel, and the condylar trajectory had an inflexion. (3) The mean values of the incisal and condylar paths of the ADDWoR group were significantly different from those in the healthy group (P<0.05), whereas there were no significant differences between the ADDWR and the healthy group (P>0.05).

Conclusion:

This study combined analysis of the condylar pathways and disc-condylar relationship to provide good visualization of morphology and kinematics during jaw movement. This process helps improve our understanding of the complexity of disk-condylar movements in subjects with TMJ internal derangement and may also contribute to our knowledge of the etiology of TMJ internal derangement.

Immunohistochemical expression of TLR-4 in temporomandibular joint dysfunction

Objective Toll-like receptor 4 (TLR-4) is a transmembrane protein involved in the innate immune system and has been implicated in the pathogenesis of temporomandibular joint dysfunction (TMD). The purpose of this study was to histologically examine the level of expression of TLR-4 relative to severity of TMD. Methods Thirty-one human TMJ disc samples were immunostained for TLR-4 and evaluated for intensity of stain. Among the samples, 8 were control samples, 16 were from patients with anterior disc displacement with reduction (ADDwR), and 7 were from patients with anterior disc displacement without reduction (ADDwoR). Results There was no statistically significant difference in intensity of stain between groupings (p = 0.673). Conclusions The results indicate a negative correlation between TMD and the expression of TLR-4.

Anterior pedicle temporalis muscle flap interposition in the treatment of TMJ disorders

Temporomandibular joint (TMJ) disorders are a common reason for consultation. Failure of medical treatments sometimes leads to the need for one of many surgical alternatives. Our purpose was to evaluate the results of anterior pedicle temporalis muscle flap interposition in the treatment of TMJ disorders.

MATERIAL AND METHODS

For this prospective study, we selected 18 patients who underwent TMJ surgery involving the interposition of a temporalis muscle flap according to a standardized technique, between January 1, 2009 and August 31, 2014. CT imaging was performed on all patients prior to surgery. We documented the etiology of TMJ dysfunction, pre and postoperative pain using a visual analogue scale (VAS), pre and postoperative (last consultation) mouth opening, and complications. We used the Wilcoxon test for our statistical analysis.

RESULTS

We observed a significant variation in preoperative and postoperative pain and mouth opening, with an average decrease in VAS values of 4.9/10 and an average increase of mouth opening of 11.1mm. No major complications were observed.

DISCUSSION

The interposition of an anterior pedicle temporalis muscle flap in the treatment of temporomandibular joint disorder is a simple and effective technique.

Platelet-rich plasma for the therapeutic management of temporomandibular joint disorders: a systematic review

This systematic review aimed to investigate whether intra-articular injections of platelet-rich plasma (PRP) are beneficial for the treatment of degenerative temporomandibular disorders, such as temporomandibular joint osteoarthritis (TMJ-OA) and disc displacement with osteoarthritic lesions, when compared to other treatments, such as injections of hyaluronic acid (HA) or saline. An electronic search of the MEDLINE and Scopus databases was performed using combinations of the terms "temporomandibular" and "platelet rich plasma", to identify studies reported in English and published up until May 2017. A hand-search of relevant journals and the reference lists of selected articles was also performed. The initial screening identified 153 records, of which only six fulfilled the inclusion criteria and were included in this review. Of these studies, three compared PRP with HA, while three compared PRP with Ringer's lactate or saline. Four of the studies found PRP injections to be superior in terms of improvements in mandibular range of motion and pain intensity up to 12 months after treatment, while the remaining two studies found similar results for the different treatments. There is slight evidence for the potential benefits of intra-articular injections of PRP in patients with TMJ-OA. However, a standardized protocol for PRP preparation and application needs to be established.

Temporomandibular joint disc perforation: a retrospective study

The aim of this study was to evaluate disc perforation diagnosed in patients undergoing arthroscopy of the temporomandibular joint (TMJ). A retrospective analysis of 33 patients with disc perforation (35 joints) was performed. Patients and joints were divided into two groups: those with distal perforation (DP; perforation of the retrodiscal tissue, or the distal area of the disc at the site of ligament insertion into the retrodiscal tissue) and those with central perforation (CP; central and anterior part of the disc). The retrospective evaluation included aetiological factors, clinical symptoms, arthroscopic findings, and the effects of arthroscopic lavage. The most frequent aetiological factors in patients with disc perforation were stress and related parafunctional activities. The most frequent arthroscopic finding in both groups was hyperaemia of the bilaminar zone and synovial tissue. Other predominant arthroscopic findings were the presence of adhesions and anterior disc dislocation in the DP group and synovial hyperplasia in the CP group. Better outcomes of arthroscopic lysis and lavage were found in the CP group than in the DP group. At 12 months after arthroscopic lavage, the results showed that the therapy was satisfactory for 72% of the joints. The most common cause of distal perforation is anterior disc dislocation, whilst chronic inflammatory changes account for central perforation.

Osteoarthrosis of Temporomandibular Joint Related to the Defects of Posterior Dentition: A Retrospective Study

Osteoarthrosis (OA) of temporomandibular joint (TMJ) is a progressive degenerative disease, gradually affecting cartilage, synovial membrane and bone structures. OA of TMJ clinically manifests with joint noises, pain and restricted mouth opening. In late stages, it results in severe damage of TMJ structures and development of ankylosis. Osteoarthrosis is a multifactorial disease; the occurrence is associated with TMJ overloading. The cohort included 619 patients [538 women (87%) and 81 men (13%), with average age 40.6 years (age range 8-89 years)] with TMJ disorder, who were examined in the year 2014 in Department of Dental Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic. The aim of this retrospective study was to analyse, if the lack of posterior teeth (supporting teeth zones) is the main etiologic factor of osteoarthrosis of TMJ. Diagnosis of OA was established on the clinical signs and the panoramic X-ray signs. Simultaneously other etiologic factors of OA were assessed. The presence of OA changes on X-ray had 171 patients (i.e. 27.6% of the total number of 619). 17.5% from these patients with OA had defect in posterior dentition. Other aetiological factors (stress, skeletal or vertebrogenous disorders) showed higher incidence of OA changes on X-ray. Defect of posterior dentition is not negligible, but it is not the main aetiological factor for osteoarthrosis of TMJ.

Clinical protocol for occlusal adjustment: Rationale and application

BACKGROUND

Occlusal adjustment can optimize the result of orthodontics, orthognathic surgery, and comprehensive restoration, and resolve adverse forces to the dentition that affect the entire masticatory system. Mounted diagnostic casts and computerized occlusal analysis offer complementary advantages for evaluating occlusal problems. Predictable occlusal adjustment is facilitated by precise, measured documentation of occlusal force by computerized occlusal analysis.

CLINICAL PRESENTATION

A conservative, structural correction of a pronounced, chronic occlusal problem by additive and subtractive occlusal adjustment was performed after a previous failed occlusal adjustment. The patient's chief concerns were significant anterior teeth fremitus in maximum intercuspation and "pain in the teeth and a poor bite" after 30+ adjustments over 2.5 years.

CLINICAL RELEVANCE

Confirmation of specific criteria for a therapeutic occlusion resolved the anterior teeth fremitus and uneven bite. Traumatic occlusal contact on posterior teeth may elicit protective mandibular repositioning affecting anterior teeth relationships and should be considered during comprehensive diagnosis.