Temporomandibular Joint Damage Research Articles

The reliability and validity of the juvenile idiopathic arthritis magnetic resonance scoring system for temporomandibular joints

In children with juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) can be involved. To prevent TMJ damage due to inflammation, early recognition is important, for which contrast-enhanced magnetic resonance imaging (MRI) is the gold standard. In this study, the interobserver reliability and construct validity of the Juvenile Idiopathic Arthritis Magnetic Resonance Scoring System for Temporomandibular Joints (JAMRIS-TMJ) was assessed. Two radiologists independently examined 38 MRIs using the JAMRIS-TMJ scoring system. Inter-observer reliability was assessed by Cohen's (weighted) kappa (κ), 95% confidence intervals (CIs) and absolute agreement (%). Construct validity was assessed by correlation between the JAMRIS-TMJ items and TMJ involvement, active maximum interincisal mouth opening (AMIO), and anterior maximum voluntary bite force (AMVBF). The interobserver reliability for the JAMRIS-TMJ items varied from poor to good (κ = 0.18–0.61). Joint enhancement had the highest reliability (κ = 0.61). Correlations were found between TMJ involvement, AMIO, and the JAMRIS-TMJ items, although variation between radiologists and TMJ side existed. No correlation was found between AMVBF and the JAMRIS-TMJ items for both radiologists. The strongest correlations were found between most of the JAMRIS-TMJ items and AMIO. Our findings support the utility of AMIO as a clinical measure of TMJ status in children with JIA.

NFkB and MMP-13 expression in condylar cartilage of temporomandibular joint with occlusal disharmony in vivo

Background: Temporomandibular disorder (TMD) is a collection of symptoms that causes pain and disturbs a person's life quality. One of the trigger factors is mechanical overloading. Mechanical overloading in occlusal disharmony conditions will lead to an inflammatory reaction in the temporomandibular joint (TMJ). This condition will induce nuclear factor Kappa Beta (NFkB) activation to transcribe proinflammatory cytokines and matrix metalloproteinase-13 (MMP13) and will also degrade condylar cartilage as a major factor in strengthening the TMJ. Purpose: The aim of this study was to analyze the expression of NFkB and MMP13 in the condylar cartilage of TMJ with occlusal disharmony. Methods: This research was an experimental study with post-test-only control group design. Twenty Rats (Rattus norvegicus) were divided into four groups: One control group without any intervention and three experimental groups. Occlusal-reducing intervention was due on the right molar of the experimental groups, which were divided into the 7th, 14th, and 21st days. Immunohistochemical staining was performed to determine the expression of NFkB and MMP13 in the condylar cartilage. The data were analyzed by using the Welch test and independent t-test. Results: There were significant differences in NFkB and MMP13 expression between the control and experiment experimental groups (p<0.05). NFkB expression increased on the 7th, 14th, and 21st days of observation. The MMP13 expression showed a significant difference between the control and experimental groups (p<0.05). Conclusion: Occlusal disharmony increases NFkB and MMP13 expression and could affect TMJ integrity and induce TMD. These findings are important for describing the mechanism of TMJ damage and developing potential alternative therapies to prevent further TMD.

THE RELATIONSHIP BETWEEN ANXIETY AND BRUXISM IN ADULTS

ABSTRACTBackground: Anxiety disorder is a psychological condition that includes worry, anxiety, and restlessness. The prevalence of emotional anxiety disorders in Indonesia is 9.9%, anxiety can cause somatic symptoms causing irritability, muscle tension and restlessness which results in the appearance of parafunctional oral activities such as bruxism. Bruxism is a bad habit of grinding and clenching teeth excessively inadvertently which involves the activity of the masticatory muscles, resulting in clinical problems in the involved teeth, such as attrition, tooth fracture, and increased sensitivity and degree of tooth mobility, exostosis and torus of the jawbone, hypertrophy of the masticatory muscles, periodontal tissue damage, and causes headaches and temporomandibular joint damage Purpose: The purpose of the literature study was to determine the relationship between anxiety and bruxism in adults Material and Methods: All reviewed articles were obtained from searching Google Scholar, Pubmed and Science Direct data sources which have a maximum journal publication time of 10 years. Results: The review was conducted in 22 journals that were responding with the inclusion criteria such as journals available in the form of full text in Indonesian or English, the subjects of the journal were people who have an adult age suffering from anxiety and bruxism. Conclusion: there is a relation between anxiety and bruxism in adult.Keywords: Adult, Anxiety, Bruxism.

Applicatoin of chitosan-based hydrogel in oral tissue engineering.

Pulpitis, periodontitis, jaw bone defect, and temporomandibular joint damage are common oral and maxillofacial diseases in clinic, but traditional treatments are unable to restore the structure and function of the injured tissues. Due to their good biocompatibility, biodegradability, antioxidant effect, anti-inflammatory activity, and broad-spectrum antimicrobial property, chitosan-based hydrogels have shown broad applicable prospects in the field of oral tissue engineering. Quaternization, carboxymethylation, and sulfonation are common chemical modification strategies to improve the physicochemical properties and biological functions of chitosan-based hydrogels, while the construction of hydrogel composite systems via carrying porous microspheres or nanoparticles can achieve local sequential delivery of diverse drugs or bioactive factors, laying a solid foundation for the well-organized regeneration of defective tissues. Chemical cross-linking is commonly employed to fabricate irreversible permanent chitosan gels, and physical cross-linking enables the formation of reversible gel networks. Representing suitable scaffold biomaterials, several chitosan-based hydrogels transplanted with stem cells, growth factors or exosomes have been used in an attempt to regenerate oral soft and hard tissues. Currently, remarkable advances have been made in promoting the regeneration of pulp-dentin complex, cementum-periodontium-alveolar bone complex, jaw bone, and cartilage. However, the clinical translation of chitosan-based hydrogels still encounters multiple challenges. In future, more in vivo clinical exploration under the conditions of oral complex microenvironments should be performed, and the combined application of chitosan-based hydrogels and a variety of bioactive factors, biomaterials, and state-of-the-art biotechnologies can be pursued in order to realize multifaceted complete regeneration of oral tissue.

Are lower urinary tract conditions more common in children with sleep bruxism?

Sleep bruxism is a parasomnia caused by rhythmic and non-rhythmic activity of the masticatory muscles during sleep. Prevalence of sleep bruxism is reported up to 40.6% in the literature. Sleep bruxism is a multifactorial issue and associated with multiple dental complications, sleep-related disorders, and psychosocial problems. We aimed to investigate if children with sleep bruxism suffer more from lower urinary tract conditions. Prospectively 128 children were included in this study. Sixty-four children constituted in the bruxism group and 64 children constituted in the control group. Children who admitted to the pediatric dentistry clinic with bruxism symptoms were recruited in the bruxism group. Control group constituted of consecutive 64 children who admitted to the pediatric dentistry clinic for routine dental examination. Parents were asked to fill out a questionnaire including Dysfunctional Voiding and Incontinence Scoring System (DVISS) form. Children's demographic data, presence of urinary frequency, presence of urgency, behaviour of voiding postponement, presence of daytime urinary incontinence, presence of enuresis nocturna, presence of fecal incontinence, presence of constipation, status of circumcision, and presence of bruxism related symptoms were recorded. Children with a DVISS score above 8 were considered to have functional voiding disorder. All children underwent a dental examination. The mean age of children was 73.3±26.9 months. For all children (n=128), the girl to boy ratio was 40:88. Mean DVISS score was 2.5±3.8 and the mean QOL score was 0.1±0.4 for all children. Eight (6.3%) children were found to have functional voiding disorder based on the DVISS score. There was no statistically significant difference for any lower urinary tract condition between the bruxism group and the control group (Table). Children with bruxism significantly had more tooth wear and masseter muscle hypertrophy (<0.001 and<0.05). Sleep bruxism has been linked to a number of health issues including dental, systemic and psychosocial problems. Tooth wears, fatigue/pain in chewing muscles, gum recession, facial pain, masseter muscle hypertrophy and temporomandibular joint damage are the main complications of bruxism. Moreover, bruxism has been associated with systemic diseases and sypmtoms like asthma, respiratory illnesses, enuresis nocturna, anxiety, and stress. Children with sleep bruxism suffer more from tooth wear, masseter muscle hypertrophy, and regional pain over the jaw. Additionally morning fatigue, relationship issues, and respiratory illnesses are more common in bruxist children. Lower urinary tract conditions are not more frequent in children with sleep bruxism.

Magnetic resonance imaging texture analysis for quantitative evaluation of the mandibular condyle in juvenile idiopathic arthritis.

Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease that affects the joints and other organs, including the development of the former in a growing child. This study aimed to evaluate the feasibility of texture analysis (TA) based on magnetic resonance imaging (MRI) to provide biomarkers that serve to identify patients likely to progress to temporomandibular joint damage by associating JIA with age, gender and disease onset age. The radiological database was retrospectively reviewed. A total of 45 patients were first divided into control group (23) and JIA group (22). TA was performed using grey-level co-occurrence matrix (GLCM) parameters, in which 11 textural parameters were calculated using MaZda software. These 11 parameters were ranked based on the p value obtained with ANOVA and then correlated with age, gender and disease onset age. Significant differences in texture parameters of condyle were demonstrated between JIA group and control group (p < 0.05). There was a progressive loss of uniformity in the grayscale pixels of MRI with an increasing age in JIA group. MRI TA of the condyle can make it possible to detect the alterations in bone marrow of patients with JIA and promising tool which may help the image analysis.

Surgical importance of the tympanic bone: multidetector computed tomography findings.

ObjectivesTo measure tympanic bone thickness (anterior-superior, anterior-inferior, and inferior wall), external ear canal length, and tympanomandibular distance that can be useful in cases that undergo tympanic bone resection.Materials and MethodsThe temporal computed tomography (CT) images of 349 patients were retrospectively evaluated. The anterior-inferior, anterior-superior, and inferior wall thicknesses; tympanomandibular distance; and external auditory canal (EAC) bone canal length were measured from the narrowest part of the canal. The shapes of the EAC in the coronal and sagittal planes were also examined.ResultsThe numbers of female and male patients were similar, and the mean age was 49.45±13.95 years. The anterior-superior, anterior-inferior, and inferior wall thicknesses were 1.92±0.60, 2.54±0.74, and 9.16±2.20 mm, respectively. The anterior-superior and anterior-inferior wall thicknesses and canal lengths were greater on the right side (P<0.001). All measurement values were higher in males, except right tympanomandibular distance (P<0.05). A non-significant negative correlation was found between the age of the participants and the left anterior-inferior wall and tympanomandibular distance on both sides. Intra-observer agreement was high for all measurements. We observed four main shapes in the external ear canal in the coronal plane Type 3, Type 2, Type 1, and Type 4 in order of frequency on the right, and Type 2, Type 3, Type 1, and Type 4 on the left. In the sagittal plane, we detected three shapes oval (74.4%), triangular (16.3%), and round (9.4%).ConclusionThe anterior wall thicknesses and tympanomandibular distance should be measured on preoperative temporal bone CT to safely perform tympanic bone anterior resection, which is required in some otological procedures, and also to prevent temporomandibular joint damage.

A model of radiation-induced temporomandibular joint damage in mice

Purpose A small animal radiation research platform (SARRP) equipped with a miniature beam system, an image-guided positioning system, and a dose planning system was used to develop and evaluate a mouse model of radiation-induced temporomandibular damage. Methods Left jaw disks of adult male C57BL/6 mice and C3H mice were targeted using the SARRP for image-guided irradiation. The total radiation dose was 75 Gy. Experiment 1 (Scoping study): Mice in the C57BL/6 mouse test and control groups were sacrificed at 1, 3, 6, 9, 12, 15, and 18 weeks after irradiation, whereas mice in the C3H test and control groups were sacrificed at 1, 3, 6, 9, and 12 weeks after irradiation. Experiment 2 (Full –scale validation study): Mice in the C57BL/6 mouse test and control groups were sacrificed at 1, 3 and 6 weeks after irradiation. Histopathological analysis of the temporomandibular skeletal muscle in each group was performed using hematoxylin and eosin (H&E) and Masson staining; the temporal mandibular bone was examined through H&E staining. Results SARRP delivered the rated dose to the temporomandibular joints of C57BL/6 and C3H mice. C3H and C57BL/6 mice in the test group showed different degrees of osteocytic necrosis and osteoporosis at different time points. H&E staining of skeletal muscle tissue showed slight fibrosis in the C57BL/6 test at 3 and 6 weeks time point. Conclusion We established a model of radiation-induced damage in the temporomandibular joint of C57BL/6 mice and demonstrated that the observed physiological and histological changes correspond to radiation damage observed in humans. Furthermore, the SARRP can deliver precise radiation doses.

Omega 3 polyunsaturated fatty acids: Potential anti-inflammatory effect in a model of ovariectomy and temporomandibular joint arthritis induction in rats

ObjectiveTo evaluate the effect of polyunsaturated fatty acid-type omega 3 (ω3) on the temporomandibular joint (TMJ) of ovariectomized rats (OVX) with rheumatoid arthritis (RA). DesignRheumatoid arthritis was induced using complete Freund's adjuvant and type II bovine collagen injected at the base of the tail. Twenty-four adult female rats were treated by gavage and divided into four groups: G1: Sham, treated with 0.9% NaCl; G2: OVX, treated with 0.9% NaCl; G3: OVX+RA treated with 0.9% NaCl; G4: OVX+RA+ω3 treated with omega 3 (300 mg/kg/day). The induction of rheumatoid arthritis in groups G3 and G4 was performed 21 days after OVX, treatments were started 15 days after the induction of rheumatoid arthritis, maintained for 7 days, and killed. Bilateral TMJs were removed and assigned to morphometric analysis by micro-computed tomography and immunoassay to assess levels of cytokines IL-1β, IL-6, TNF-α, and IL-10. ResultsHigher levels of inflammatory cytokines were found in the G2 and G3 (P < 0.05) and anti-inflammatory cytokines in the G1 and G4. TMJ analysis by micro-computed tomography showed a higher percentage of bone volume (median - interquartile deviation) in G1 (96.2–1.1) than in the G2 (91.5–2.0, P = 0.0374) and G3 (85.1–5.2, P = 0.0001) but showed no statistically significant differences with the G4 (93.1–1.7, P = 0.79). ConclusionsOmega 3 successfully reduced TMJ damage in rats caused by ovariectomy and induced rheumatoid arthritis, and is a promising alternative for bone repair and attenuation of inflammatory processes.

Relationship between Clinical Symptoms and Magnetic Resonance Imaging in Temporomandibular Disorder (TMD) Patients Utilizing the Piper MRI Diagnostic System.

Clinical problems of the temporomandibular joint (TMJ) and the masticatory musculature are both included in the term temporomandibular disorder (TMD). The purpose of the present study was to examine the pathology of the joints of patients diagnosed with TMD utilizing the dedicated Piper MRI-based classification, and to link these pathologies with various symptoms while considering their severity. In total, 64 patients with clinical TMD were examined. Symptoms were recorded using a questionnaire. The clinical examination included diagnosing the occlusion in centric relation, which was followed by a standardized MRI. It was confirmed that, although they occurred in a high percentage in all classes, muscle pain and occlusal interference are not indicators of TMJ damage. The results indicate that the progressive degradation of the TMJ, represented by qualification to the higher Piper classes, is associated with an increase in TMJ pain only up to a certain stage. For the highest Piper classes, the joint pain occurs in a smaller percentage of patients, but sounds are more frequent.

Biomechanical effects of high acceleration on the temporomandibular joint

The symptoms of temporomandibular disorders (TMD) are easily developed in pilots after long flights, such as joint pain, anterior displacement disc and so on. Related studies have suggested that abnormal high acceleration would cause temporomandibular joint (TMJ) lesions. Therefore, the purpose of this study is to analyze the biomechanical effects of high acceleration on the TMJs. The 3D models of the maxilla, mandible, articular disc were generated by Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) of a healthy volunteer without any TMD symptoms. Then, the loads were added according to the various operating conditions of the aircraft. The maximum tensile stress, occurred in the anterior band of the discs, exceeded the failure stress. Compared with the low acceleration, the contact stresses between the discs and the articular cartilages were much greater under the high acceleration. High acceleration had a negative impact on the stress distributions of the articular discs and cartilages and easily led to TMJ damage. Lateral acceleration will cause asymmetric stress distribution of the TMJs.

Temporomandibular joint damage in K/BxN arthritic mice

Rheumatoid arthritis (RA) is an autoimmune disease affecting 1% of the world population and is characterized by chronic inflammation of the joints sometimes accompanied by extra-articular manifestations. K/BxN mice, originally described in 1996 as a model of polyarthritis, exhibit knee joint alterations. The aim of this study was to describe temporomandibular joint (TMJ) inflammation and damage in these mice. We used relevant imaging modalities, such as micro-magnetic resonance imaging (μMRI) and micro-computed tomography (μCT), as well as histology and immunofluorescence techniques to detect TMJ alterations in this mouse model. Histology and immunofluorescence for Col-I, Col-II, and aggrecan showed cartilage damage in the TMJ of K/BxN animals, which was also evidenced by μCT but was less pronounced than that seen in the knee joints. μMRI observations suggested an increased volume of the upper articular cavity, an indicator of an inflammatory process. Fibroblast-like synoviocytes (FLSs) isolated from the TMJ of K/BxN mice secreted inflammatory cytokines (IL-6 and IL-1β) and expressed degradative mediators such as matrix metalloproteinases (MMPs). K/BxN mice represent an attractive model for describing and investigating spontaneous damage to the TMJ, a painful disorder in humans with an etiology that is still poorly understood.

IL-1β Damages Fibrocartilage and Upregulates MMP-13 Expression in Fibrochondrocytes in the Condyle of the Temporomandibular Joint.

The temporomandibular joint (TMJ), which differs anatomically and biochemically from hyaline cartilage-covered joints, is an under-recognized joint in arthritic disease, even though TMJ damage can have deleterious effects on physical appearance, pain and function. Here, we analyzed the effect of IL-1β, a cytokine highly expressed in arthritic joints, on TMJ fibrocartilage-derived cells, and we investigated the modulatory effect of mechanical loading on IL-1β-induced expression of catabolic enzymes. TMJ cartilage degradation was analyzed in 8–11-week-old mice deficient for IL-1 receptor antagonist (IL-1RA−/−) and wild-type controls. Cells were isolated from the juvenile porcine condyle, fossa, and disc, grown in agarose gels, and subjected to IL-1β (0.1–10 ng/mL) for 6 or 24 h. Expression of catabolic enzymes (ADAMTS and MMPs) was quantified by RT-qPCR and immunohistochemistry. Porcine condylar cells were stimulated with IL-1β for 12 h with IL-1β, followed by 8 h of 6% dynamic mechanical (tensile) strain, and gene expression of MMPs was quantified. Early signs of condylar cartilage damage were apparent in IL-1RA−/− mice. In porcine cells, IL-1β strongly increased expression of the aggrecanases ADAMTS4 and ADAMTS5 by fibrochondrocytes from the fossa (13-fold and 7-fold) and enhanced the number of MMP-13 protein-expressing condylar cells (8-fold). Mechanical loading significantly lowered (3-fold) IL-1β-induced MMP-13 gene expression by condylar fibrochondrocytes. IL-1β induces TMJ condylar cartilage damage, possibly by enhancing MMP-13 production. Mechanical loading reduces IL-1β-induced MMP-13 gene expression, suggesting that mechanical stimuli may prevent cartilage damage of the TMJ in arthritic patients.

Experimental Methods to Inform Diagnostic Approaches for Painful TMJ Osteoarthritis

Temporomandibular joint (TMJ) osteoarthritis (OA) is a degenerative disease of the joint that can produce persistent orofacial pain as well as functional and structural changes to its bone, cartilage, and ligaments. Despite advances in the clinical utility and reliability of the Diagnostic Criteria for Temporomandibular Disorders, clinical tools inadequately predict which patients will develop chronic TMJ pain and degeneration, limiting clinical management. The challenges of managing and treating TMJ OA are due, in part, to a limited understanding of the mechanisms contributing to the development and maintenance of TMJ pain. OA is initiated by multiple factors, including injury, aging, abnormal joint mechanics, and atypical joint shape, which can produce microtrauma, remodeling of joint tissues, and synovial inflammation. TMJ microtrauma and remodeling can increase expression of cytokines, chemokines, and catabolic factors that damage synovial tissues and can activate free nerve endings in the joint. Although studies have separately investigated inflammation-driven orofacial pain, acute activity of the trigeminal nerve, or TMJ tissue degeneration and/or damage, the temporal mechanistic factors leading to chronic TMJ pain are undefined. Limited understanding of the interaction between degeneration, intra-articular chemical factors, and pain has further restricted the development of targeted, disease-modifying drugs to help patients avoid long-term pain and invasive procedures, like TMJ replacement. A range of animal models captures features of intra-articular inflammation, joint overloading, and tissue damage. Although those models traditionally measure peripheral sensitivity as a surrogate for pain, recent studies recognize the brain’s role in integrating, modulating, and interpreting nociceptive inputs in the TMJ, particularly in light of psychosocial influences on TMJ pain. The articular and neural contributors to TMJ pain, imaging modalities with clinical potential to identify TMJ OA early, and future directions for clinical management of TMJ OA are reviewed in the context of evidence in the field.

Temporomandibular joint damage in juvenile idiopathic arthritis: Diagnostic validity of diagnostic criteria for temporomandibular disorders.

Diagnostic criteria reported in the expanded taxonomy for temporomandibular disorders include a standardised clinical examination and diagnosis (DC/TMD 3.B) of temporomandibular joint (TMJ) damage in patients with juvenile idiopathic arthritis (JIA); however, their validity is unknown. To assess the validity of DC/TMD 3.B for the identification of TMJ damage in JIA-patients, using magnetic resonance imaging (MRI) as gold standard, and to investigate the relation between clinical findings and TMJ damage. Fifty consecutive JIA patients (9-16years) were recruited. DC/TMD 3.B were compared with TMJs MRI (100TMJs) performed maximum at 1month from the visit. The severity of TMJ damage was scored in four grades. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), logistic regression models with odds ratio of DC/TMD 3.B and clinical findings respect to MRI were calculated. The DC/TMD 3.B were inadequate in the identification of TMJ damage (sensitivity=0.15, specificity=0.92, PPV=0.85, NPV=0.28, P=0.350). Chin deviation and TMJ crepitus were associated with worse TMJ damage (P=0.006; P=0.034). Reduced mouth opening (OR=3.91, P=0.039) and chin deviation (OR=13.7, P=0.014) were associated with the presence of TMJ damage. Combining "pain" (history of pain, TMJ pain, pain during movements) and "function" (TMJ crepitus, reduced mouth opening, chin deviation) clinical findings, the sensitivity and the specificity were 0.88 and 0.54. DC/TMD 3.B present a low sensitivity to diagnose TMJ damage. Chin deviation, reduced mouth opening and TMJ crepitus are associated with TMJ damage. We suggest combining "pain" and "function" findings for the evaluation of TMJ damage in JIA patients.

Micronized palmitoylethanolamide reduces joint pain and glial cell activation.

Temporomandibular disorder (TMD) is a common painful condition in the temporomandibular joint (TMJ). Joint inflammation is believed to be a chief cause of pain in patients with TMD, through the release of pro-inflammatory cytokines that induce peripheral sensitization of nerve terminals followed by microglial stimulation. TMJ was induced in rats with the injection of complete Freund's adjuvant (CFA) emulsion into the left TMJ capsule. The present study would assess the effects of micronized palmitoylethanolamide (m-PEA) on glial activation and trigeminal hypersensitivity. Ten mg/kg m-PEA or corresponding vehicle was administered 1h after CFA and mechanical allodynia and edema were evaluated at 24 and 72h after CFA injection. CFA-injected animals showed TMJ edema and ipsilateral mechanical allodynia accompanied by a robust growth in GFAP protein-positive satellite glial cells and activation of resident macrophages in the TG. Moreover, m-PEA administration significantly reduced the degree of TMJ damage and pain, macrophage activation in TG and up-regulation of Iba1. The results confirm that m-PEA could represent a novel approach for monitoring pain during trigeminal nerve sensitization.

Implication of general anaesthetic and sedation techniques in temporomandibular joint disorders-a systematic review.

The purpose of this study was to conduct a systematic review of the literature on temporomandibular joint damage directly related to general anaesthesia and sedation. We searched MEDLINE, SCOPUS and the COCHRANE Library for titles and abstracts containing terms related to the subject. The search delimiters were analytical and descriptive studies with abstracts in Spanish, German, English or French, with no time limit. The search was updated in January 2015. Of the 398 articles found, 89 were duplicates and only 28 were of interest. Of these, 23 (82.14%) were case and case series reports, 4 (14.28%) were longitudinal studies and 1 (3.57%) was a cross-sectional study. General anaesthesia and sedation are risk factors for temporomandibular joint damage because of the drop in muscle tone caused by the drugs employed and because of airway management manoeuvres involving the joint. Joint complications have been described with spontaneous ventilation as well as with ventilation assisted by a face or laryngeal mask and with intubation. They are more frequent in women and/or patients with previous temporomandibular problems. Proper assessment is required both before and after anaesthesia or sedation in order to foresee and avoid or minimize temporomandibular complications. The data should be treated with caution, as the evidence of case and case series reports is not of a high standard and the small number of analytical studies is not entirely comparable. General anaesthesia and sedation techniques can influence the onset of temporomandibular joint disorders. More studies are needed to provide better clinical evidence.

Evaluation of the effect of different mandibular fractures on the temporomandibular joint using magnetic resonance imaging: five years of follow-up

A prospective cohort study was performed to investigate concurrent and delayed temporomandibular joint (TMJ) injuries following different types of mandibular fracture using magnetic resonance imaging (MRI). One hundred adult male patients with a recent history of mandibular fracture were included. The patients were divided into five groups according to the site of fracture. The patients underwent MRI within 10 days of the primary injury. The same clinical, radiographic, and MRI examinations were performed 5 years later. The aetiological factor of the mandibular fractures was a road traffic accident in all cases. The results of the study suggest that there is no direct correlation between TMJ pain and the presence of MRI changes. Patients who had a condylar fracture associated with a fracture of the angle or body could develop more TMJ damage on both sides. TMJs on the same side as the fractures could develop internal derangement as a result of the acute stage of the trauma and its delayed consequences. Trauma caused more delayed TMJ derangement on the non-fractured side than on the fractured side of the mandible. Disturbances of the TMJ on the side of the fracture develop during both the acute stage and follow-up.

Radiation-induced temporo-mandibular joint disorder in post-radiotherapy nasopharyngeal carcinoma patients: assessment and treatment.

Nasopharyngeal carcinoma (NPC) is endemic in southern China, and its incidence in Hong Kong is relatively high. Radiotherapy is the mainstay treatment for NPC due to its relatively high radiosensitivity and deep‐seated anatomical position, which is not readily accessible by surgery. Although the technique of radiotherapy in NPC has been advancing and offers promising treatment outcome, complications around the irradiation areas are inevitable and the quality of life of the post‐radiotherapy patients is often compromised. Trismus, which is defined as the restricted mouth opening or jaw movement due to the disorder of temporo‐mandibular joint (TMJ), is one of the possible late complications for radiotherapy of NPC and is found in 5–17% of the post‐radiotherapy (post‐RT) patients. Trismus at early stage may only affect the speech, but in severe cases nutritional intake and oral hygiene condition may deteriorate seriously. This article reviewed the possible causes of radiation‐induced TMJ damage, the various assessments including imaging modalities and possible treatments. The conclusion is that the availability of simple, yet effective examinations for trismus is essential for delaying the progression and restoring TMJ functions. Although there is no absolutely effective treatment for trismus, many supportive, restorative and palliative management are possible under different clinical situations.

Infrared Thermographic Analysis of Craniofacial Muscles in Military Pilots Affected by Bruxism

Due to the physical stresses to which they are subjected, military pilots may experience bruxism, an "oral parafunction." Parafunction can cause masticatory muscle suffering and serious dental, periodontal, and temporomandibular joint damage. The aim of this pilot study was to analyze the temperature distribution in masticatory and upper trapezius muscles in a sample of bruxist air force pilots, to evaluate whether an occlusal splint would be able to induce skin temperature variations in the stomatognathic apparatus using the technology of infrared thermography. A total of 11 male Italian Air Force pilots of high performance aircraft, ages from 27 to 40 yr (mean 34.91 ± 2.15 yr) with 1000-3000 flight hours, were enrolled in the study and analyzed using an infrared camera in order to evaluate the temperature of the masticatory muscles. All the recordings were taken on each subject using the same protocol with and without a temporary occlusal splint. The occlusal splint statistically increased each muscle temperature (0.10-0.20°C) on both the sides of the body. No statistically significant differences were found between the left and right muscles (asymmetries) before or after the wearing of the splint except for the anterior temporalis muscle. No significant improvement or variations in temperature symmetry of this muscle was found after the application of the splint. The use of an occlusal splint could help in increasing muscles temperatures in Air Force pilots with consequent relaxation of their facial muscular system.