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Who Owns YOUR TMJ Implant?

Especially during this past year, it’s been brought to our attention by a number of TMJ implant patients having their implants removed that...

Social Security Disability Benefits and Temporomandibular Disorders

Those who suffer from Temporomandibular Disorders also referred to as TMJ or TMD, may find it impossible to maintain the responsibilities...

Pain Sensitivity and Genetic Factors: Act Two of the OPPERA Study

This month we present the last set of findings from “Act Two” of the Oral Pain: Prospective Evaluation and Risk Assessment (OPPERA)...

Symptoms, Sociodemographics, & Psychological Profile: Act Two of the OPPERA Study

Last month we began our report on findings in OPPERA's Act Two," the second series of analyses of data from the Orofacial Pain Prospective...

Temporomandibular Disorders and Sexual Intimacy

A recent posting on the TMJA website included the following request: "I wonder if you could include something in a future newsletter about...

The Latest in TMJ Science

Aug 9, 2013

The TMJ Association, Ltd.  (TMJA) is dedicated to providing TMJ patients, scientists and the general public with timely information on the latest scientific developments in the TMJ field.  We've assembled the following information in one place to help educate you as well as save you time and effort in your search for what's the latest in TMJ research. 

August 6, 2013 - Septic arthritis of the temporomandibular joint: case reports and review of the literature

" The authors reviewed the available literature regarding the presentation, evaluation, treatment, and clinical course of TM joint septic arthritis, focusing on elements relevant to emergency physicians. Septic arthritis of the TM joint may be caused by hematogenous spread of distant infection or local spread of deep masticator space infections. Patients may present with TM joint septic arthritis acutely or sub–acutely. Septic arthritis of the TM joint should be considered in the differential diagnosis of patients who present with trismus and pain or fever."

August 1, 2013 - Defining neurochemical properties and functions of primary sensory neurons in the rat trigeminal ganglion

"Taken together, our findings support the emerging picture of a complex combinatorial pattern of co-expression of sensory neurochemicals, transducers and receptor components that help to define TG neuronal modality and function. We would advocate caution in making generalisations across sensory ganglia in particular in extrapolating data from the DRG to the trigeminal ganglion."

August 1, 2013 - Temporomandibular joint ankylosis: Is hypercoagulable state of blood a predisposing factor?

"It is postulated that hypercoagulability/reduced fibrinolytic activity in these as well as non-EHPVO patients with TMJ ankylosis cases may have predisposed them to the development of joint ankylosis. The possible mechanism is explained and correlated with other causes of TMJ ankylosis and known facts of protein C deficiency/activated protein C resistance."

August 1, 2013 - Cytopathologic diagnosis on joint lavage fluid for patients with temporomandibular joint disorders

" The results suggested that cytopathologic examination of the joint lavage fluids from TMD patients is helpful for gaining an understanding of the inner local conditions of TMJ at the cellular level."

August 2013 - A discoidin domain receptor 1 knock-out mouse as a novel model for osteoarthritis of the temporomandibular joint

"Therefore, the DDR-1 knock-out mouse can serve as a novel model for temporomandibular disorders, such as OA of the TMJ, and will help to develop new treatment options, particularly those involving tissue regeneration."

August 2013 - Enzyme histochemical adaptive responses of the medial pterygoid muscle and two heads of the lateral pterygoid muscle to long-term soft diet feeding in growing rabbits

"In conclusion, this study suggests that long-term soft diet leads to adaptations of the pterygoid muscles. Two heads of the lateral pterygoid muscle revealed different adaptation from jaw-closing muscles under soft-diet conditions."

August 2013 - Effects of occlusal stabilization splints on obstructive sleep apnea: a randomized controlled trial

"The use of an occlusal stabilization splint is associated with a risk of aggravation of obstructive sleep apnea; however, the effect size was small, which reduces the clinical relevance of the study."

August 15, 2013 - Reduced GABAA receptor α6 expression in the trigeminal ganglion enhanced myofascial nociceptive response

"From these results we conclude GABAA receptors consisting of the Gabrα6 subunit inhibit TG nociceptive sensory afferents in the trigeminal pathway and have an important role in the regulation of myofascial nociception."

August 13, 2013 - Temporomandibular joint pain: A critical role for Trpv4 in the trigeminal ganglion

"Thus, TRPV4 is necessary for masticatory sensitization in TMJ inflammation and probably functions upstream of MEK/ERK phosphorylation in trigeminal ganglion sensory neurons in vivo. TRPV4 therefore represents a novel pronociceptive target in TMJ inflammation and should be considered a target of interest in human TMJD."

August 2013 - 1,25(OH)2D deficiency induces temporomandibular joint osteoarthritis via secretion of senescence-associated inflammatory cytokines

"Our results indicate that 1,25(OH)2D plays an important role in preventing the development and progression of OA."

August 2013 - A cross-sectional study of the relationship between serum sexual hormone levels and internal derangement of temporomandibular joint

"Lower progesterone level in women with TMD can suggest the more important role of this hormone in the development of the disorder."

August 2013 - Tensile characterization of porcine temporomandibular joint disc attachments

"The frequency and impact of temporomandibular joint (TMJ) disorders necessitate research in characterizing the joint's function. The 6 discal attachments have not yet been systematically characterized under tension. Understanding their role in joint function may guide our study of TMJ pathologies, including disc displacement. In the present study, a porcine model was used to characterize the attachments in tension anteroposteriorly and mediolaterally, based on previously identified similarities in the porcine and human masticatory behaviors and discal properties. Tensile stiffness, strength, toughness, and maximum strain were quantified. Collagen alignment was characterized via polarized light and scanning electron microscopy. Anisotropy was demonstrated in all attachments, with the exception of the anterior inferior attachment. Anteroposteriorly, the lateral attachment was stiffest (8.3 MPa) and the anterior superior was least stiff (1.4 MPa). Mediolaterally, the posterior superior attachment was stiffest (16.3 MPa) and the medial was least stiff (1.4 MPa). The greatest strain was observed in the lateral attachment in the mediolateral direction and the posterior superior attachment in the anteroposterior direction. With greatest strains in the most commonly observed directions of disc displacement, it is suggested that compromise in the posterior and lateral attachments contributes to partial lateral and anterior disc displacement."

July 17, 2013 - Primary treatment of temporomandibular disorders: The Japanese Society for the temporomandibular joint evidence-based clinical practice guidelines

"In 2010 and 2012, the clinical practice guidelines committee of the Japanese Society for the temporomandibular joint published clinical guidelines for the primary treatment of temporomandibular disorders (TMDs) using the principles of evidence-based medicine (EBM) and the grading of recommendations assessment, development and evaluation (GRADE) approach. In the present review, we provide the results of our search and summation of the relevant TMD studies and the updated treatment guidelines.

1.Splint therapy: for masticatory muscle pain patients, we recommend the use of a maxillary stabilization splint (a thin and full occlusal coverage appliance made from hard acrylic resin), after informed consent is obtained from the patient by disclosing sufficient information on the appropriate indications, purpose, possible harm and burden, and any alternatives to the treatment (Grade 2C).

 2.Physical therapy: for TMD patients who are suffering from a mouth-opening disturbance caused by disk displacement, we suggest the optimal use of a manual and self-mouth-opening exercise with/without NSAID administration after sufficient information on disease including disk position is provided to the patient (Grade 2B).

 3.Occlusal adjustment: for TMD symptoms, we recommend against occlusal adjustment about primary treatment (Grade 1D)."

July 17, 2013 - Sex differences and hormonal modulation of deep tissue pain

"Women disproportionately suffer from many deep tissue pain conditions. Experimental studies show that women have lower pain thresholds, higher pain ratings and less tolerance to a range of painful stimuli. Most clinical and epidemiological reports suggest female gonadal hormones modulate pain for some, but not all, conditions. Similarly, animal studies support greater nociceptive sensitivity in females in many deep tissue pain models. Gonadal hormones modulate responses in primary afferents, dorsal horn neurons and supraspinal sites, but the direction of modulation is variable. This review will examine sex differences in deep tissue pain in humans and animals focusing on the role of gonadal hormones (mainly estradiol) as an underlying component of the modulation of pain sensitivity."

July 15, 2013 - Facial pain with localized and widespread manifestations: separate pathways of vulnerability

"Human association studies of common genetic polymorphisms have identified many loci that are associated with risk of complex diseases, although individual loci typically have small effects. However, by envisaging genetic associations in terms of cellular pathways, rather than any specific polymorphism, combined effects of many biologically-relevant alleles can be detected. The effects are likely to be most apparent in investigations of phenotypically-homogenous subtypes of complex diseases. We report findings from a case-control, genetic association study of relationships between 2,925 SNPs and two subtypes of a commonly occurring chronic facial pain condition, temporomandibular disorder (TMD): 1)localized TMD; and 2)TMD with widespread pain. When compared to healthy controls, cases with localized TMD differed in allelic frequency of SNPs that mapped to a serotonergic receptor pathway (P=0.0012), while cases of TMD with widespread pain differed in allelic frequency of SNPs that mapped to a T-cell receptor pathway (P=0.0014). A risk index representing combined effects of six SNPs from the serotonergic pathway was associated with greater odds of localized TMD (odds ratio = 2.7, P=1.3x10-9), and the result was reproduced in a replication case-control cohort study of 639 people (odds ratio = 1.6, P=0.014). A risk index representing combined effects of eight SNPs from the T-cell receptor pathway was associated with greater odds of TMD with widespread pain (P=1.9x10-8), although the result was not significant in the replication cohort. These findings illustrate potential for clinical classification of chronic pain based on distinct molecular profiles and genetic background."

July 15, 2013 - Influence of sleep deprivation on expression of MKK4 and c-fos in the mandibular condylar cartilage of rats

"These results indicate that the variation in expression of MKK4 and c-fos may be correlated with pathological changes induced by sleep deprivation in mandibular condylar cartilage in rats."

July 10, 2013 - Prospective analysis of the incidence of metal allergy in patients listed for total replacement of the temporomandibular joint

"We prospectively analysed the incidence of metal allergies in patients listed for total replacement of the temporomandibular joint (TMJ) and the efficacy of patch testing to prevent rejection phenomena. All patients (n=101) that required a prosthetic TMJ between March 2004 and August 2012 were tested preoperatively. A total of 39% had an allergy to one or more metals and they were given all-titanium prostheses. Following the introduction of this protocol no patients have shown signs of an allergic rejection within 6 months of operation. We suggest that all patients listed for total TMJ replacement should have patch tests for metal allergies and that all-titanium prostheses are used when allergy is detected."

July 3, 2013 - Accuracy study of the main screening tools for temporomandibular disorder in children and adolescents

"The aims of the present study were to assess the degree of sensitivity and specificity of the screening questionnaire recommended by the American Academy of Orofacial Pain (AAOP) and the patient-history index proposed by Helkimo (modified by Fonseca) and correlate the findings with a clinical exam. All participants answered the questionnaires and were submitted to a clinical exam by a dentist who had undergone calibration training. Both the AAOP questionnaire and Helkimo index achieved low degrees of sensitivity for the detection of temporomandibular disorder (TMD), but exhibited a high degree of specificity. With regard to concordance, the AAOP questionnaire and Helkimo index both achieved low levels of agreement with the clinical exam. The different instruments available in the literature for the assessment of TMD and examined herein exhibit low sensitivity and high specificity when administered to children and adolescents stemming from difficulties in comprehension due to the age group studied and the language used in the self-explanatory questions."

July 2013 - Pressure and inflammatory stimulation induced increase of cadherin-11 is mediated by PI3K/Akt pathway in synovial fibroblasts from temporomandibular joint

"These findings suggest that cadherin-11 may play important roles in SFs following exposure to mechanical loading and inflammatory stimulation. In addition, PI3K/Akt pathway was associated with pressure or inflammation-induced cadherin-11 expression, which may involve in the pathogenesis of temporomandibular diseases."

June 27, 2013 - Headache and Co-morbid Pains Associated with TMD Pain in Adolescents

"When participants were grouped according to headache onset and TMD pain, the highest association between headache and TMD pain was found in the subgroup “Headache onset before TMD pain” (OR 9.4). In conclusion, headache appears to be independently and highly associated with TMD pain in adolescents. Neck pain and somatic complaints were also significantly associated with TMD pain. Headache seems to precede TMD pain in many adolescents with pain."

June 26, 2013 - Inconclusive results of a systematic review of efficacy of antidepressants on orofacial pain disorders

"Data sourcesMedline.Study selectionSingle or double blinded randomised controlled trials (RCTs), in patients suffering from orofacial pain disorders, with pain intensity as main outcome measure and antidepressants as treatment modality were included. Study quality was assessed using a 15-item checklist.Data extraction and synthesisTwo independent investigators extracted the data and a qualitative summary was presented.ResultsSix trials were included; four studies were randomised placebo-controlled trials and two were randomised active-controlled trials. All six trials were of high quality according to the 15-item criteria. Because of the heterogeneity of treatment modalities and the low number of trials per disorder there was limited evidence to support the effectiveness of antidepressants in orofacial pain disorders.ConclusionsMore randomised controlled trials are needed to come to a firm conclusion for the use of antidepressants for orofacial pain disorders."

June 15, 2013 - Effect of Mechanical Strain on Solute Diffusion in Human TMJ Discs: An Electrical Conductivity Study

"The results indicated that mechanical strain significantly impeded solute diffusion through the disc. This mechanical strain effect was larger in the female than in the male human TMJ disc. This study may provide new insights into TMJ pathophysiology."

June 2013 - Peripheral Metabotropic Glutamate Receptor Subtype 5 Contributes to Inflammation-Induced Hypersensitivity of the Rat Temporomandibular Joint

"These findings indicate a role for peripheral mGluR5 in CFA-induced nociceptive behavior and TMJ inflammation. Peripheral application of mGluR5 antagonists could provide therapeutic benefits for inflammatory TMJ pain."

June 2013 - The treatment and diagnosis of temporomandibular disorders using high-tech devices

The scientific literature does not support the use of electronic diagnostic and treatment devices for TMD.

June 2013 - The phenotypic and genetic signatures of common musculoskeletal pain conditions

Musculoskeletal pain conditions, such as fibromyalgia and low back pain, tend to coexist in affected individuals and are characterized by a report of pain greater than expected based on the results of a standard physical evaluation. The pathophysiology of these conditions is largely unknown, we lack biological markers for accurate diagnosis, and conventional therapeutics have limited effectiveness. Growing evidence suggests that chronic pain conditions are associated with both physical and psychological triggers, which initiate pain amplification and psychological distress; thus, susceptibility is dictated by complex interactions between genetic and environmental factors. Herein, we review phenotypic and genetic markers of common musculoskeletal pain conditions, selected based on their association with musculoskeletal pain in previous research. The phenotypic markers of greatest interest include measures of pain amplification and 'psychological' measures (such as emotional distress, somatic awareness, psychosocial stress and catastrophizing). Genetic polymorphisms reproducibly linked with musculoskeletal pain are found in genes contributing to serotonergic and adrenergic pathways. Elucidation of the biological mechanisms by which these markers contribute to the perception of pain in these patients will enable the development of novel effective drugs and methodologies that permit better diagnoses and approaches to personalized medicine.

June 2013 -

Clinical Assessment of Patients with Orofacial Pain and Temporomandibular Disorders

"Accurate diagnosis of chronic pain disorders of the mouth, jaws, and face is frequently complex. It is common for patients with chronic orofacial pain to consult multiple clinicians and receive ineffective treatment before a correct diagnosis is reached. This problem is a significant public health concern. Clinicians can minimize error by starting the diagnostic procedure with a careful, accurate history and thorough head and neck examination followed by a thoughtfully constructed differential diagnosis. The possibility that the patient has symptoms of a life-threatening underlying disease rather than a more common dental, sinus, or temporomandibular disorder must always be considered."

May 23, 2013 - Genome-wide association study of degenerative bony changes of the temporomandibular joint

"Our GWAS identified 22 independent loci showing suggestive association signals with degenerative bony changes of the TMJ. These loci provide good candidates for future follow-up studies."

May 23, 2013 - Diagnosis and Treatment of Temporomandibular Disorders: An Ethical Analysis of Current Practices

"The defining characteristic of a profession – and especially a health–care profession – is that the behaviour of its members is proscribed by a formal code of ethics. The main purpose of such codes is to guide practitioners' interactions with patients, assuring that patient interests are protected. In other words, the ethical code requires practitioners to place their patients' needs for proper diagnosis and appropriate treatment ahead of their own needs for income and advancement. Debate of these issues should not be solely focused on scientific merit, but also upon the compelling ethical obligations that dentists have as a result of the contemporary scientific literature regarding TMDs."

May 2013 - Outcomes of open temporomandibular joint surgery following failure to improve after arthroscopy: is there an algorithm for success?

"Open surgical management of the TMJ can benefit patients despite the previous failure of arthroscopy to manage pain, restriction, and locking. Arthroscopy seems to reduce the percentage of patients that need open TMJ surgery, but also the success of subsequent operations compared with previous studies. TMJ replacement is increasingly being done successfully to treat end-stage disease. These results may be used when obtaining a patient's consent for open TMJ surgery, particularly if they are in the groups considered to have a high risk of subsequently requiring a replacement joint."

May, 2013 - Multisystem Dysregulation in Painful Temporomandibular Disorders

"The concurrent assessment of multiple physiological and psychological systems is critical to our understanding of the pathophysiological processes that contribute to painful TMD and associated comorbid conditions, which will ultimately guide and inform appropriate treatment strategies that address the multisystem dysregulation associated with complex and common persistent pain conditions."

April 18, 2013 - Association between posterior crossbite, masticatory muscle pain, and disc displacement: a systemic review

"It is not possible to establish an association between posterior crossbite, muscle pain, and disc displacement because the distribution of the studies supporting or not supporting the association is similar. The consequences of posterior crossbite on the development of TMDs deserve further investigations, with high sample size, well-defined diagnostic criteria, and rigorous scientific methodologies. Finally, long-term controlled studies are needed to identify posterior crossbite as a possible risk factor for TMDs."

April, 2013 - Temporomandibular Joints in Asymptomatic and Symptomatic Nonpatient Volunteers: A Prospective 15-year Follow-up Clinical and MR Imaging Study

"Volunteers with mild symptoms had a prevalence of disk displacement of the same magnitude as that reported in patients, although most volunteers, symptomatic as well as asymptomatic, maintained their TMJ status during 15 years."

March 20, 2013 - Stress, Estrogen Connect Co-Occurrence of Irritable Bowel Syndrome, Temporomandibular Disorders

"As more than 60 percent of women with temporomandibular disorders (TMD) also exhibit abdominal pain consistent with irritable bowel syndrome (IBS) symptoms, two researchers in the neural and pain sciences department of the University of Maryland School of Dentistry, in Baltimore, have developed a model to better illustrate the two conditions’ comorbidity."

February 5, 2013 - Laser acupuncture in patients with temporomandibular dysfunction: a randomized controlled trial

"For patients in whom conservative treatment was adopted, the laser acupuncture is a secure, noninvasive, and effective treatment modality because it improves the chronic pain associated with TMD and has no side effects."

January 28, 2013 - Intra-articular steroid injection for temporomandibular joint arthritis in juvenile idiopathic arthritis: A systematic review on efficacy and safety

"The current level of evidence allows only very limited conclusions on the effect of intra-articular coricosteroid injection (IACI) therapy in patients with TMJ arthritis. Knowledge on the long-term impact of IACI on mandibular growth is not available. Future studies designed in accordance with evidence-based standards are needed to allow a more general conclusion on efficacy and safety of this treatment modality in patients with TMJ arthritis."

January 23, 2013 - The Prevalence of Comorbid Symptoms of Central Sensitization Syndrome Among Three Different Groups of Temporomandibular Disorder Patients

"Symptoms of central sensitization syndrome (CSS) were evaluated among three different groups of temporomandibular disorder (TMD) patients. Additionally, TMD group differences in pain and pain-related disability were assessed, as well as emotional distress. Participants were 250 patients with symptoms of acute TMD, recruited from dental clinics within a major metropolitan area. Sequential regressions and multivariate analyses of covariance were conducted in order to make group comparisons. Those with a TMD Muscle Disorder (ie, myofacial TMD [m-TMD]) and those with more than one TMD diagnosis had the most symptoms of CSS and higher reports of pain and pain-related disability. Moreover, emotional distress accounted for a substantial amount of the variance for physical symptoms and mediated all TMD comparisons. Myofacial TMD is characterized by a high degree of comorbidity of symptoms of CSS and associated emotional distress."

January 2, 2013 - A new surgical classification for temporomandibular joint disorders

"The role of temporomandibular joint (TMJ) surgery is ill-defined, so a universal classification is needed to collate the evidence required to justify the surgical interventions undertaken to treat TMJ disorders. The aim of this article is to introduce a new classification that divides TMJ disorders into 5 categories of escalating degrees of joint disease that can be applied to TMJ surgery. Using a category scale from 1 to 5, with category 1 being normal, and category 5 referring to catastrophic changes to the joint, the new classification will provide the basis for enhanced quantitative and descriptive data collection that can be used in the field of TMJ surgery research and clinical practice. It is hoped that this new classification will form the basis of what will eventually become the universal standard surgical classification of TMJ disorders that will be adopted by both researchers and clinicians so that ultimately, the role of TMJ surgery will be based on evidence rather than conjecture."

December, 2012 - Sleep bruxism and myofascial temporomandibular disorders: A laboratory-based polysomnographic investigation

"Although other reasons to consider treating sleep bruxism (SB) may exist, misplaced concern about SB's sustaining or exacerbating a chronic myofascial TMD condition should not be used to justify SB treatment."

December 18, 2012 - Dysregulation of the autonomous nervous system in patients with temporomandibular disorder: a pupillometric study

"Taken together, these data suggest that TMD subjects have an impairment of the sympathetic-adrenergic component of the ANS to be activated under stress. The present study provides preliminary pupillometric data confirming that adrenergic function is dysregulated in patients with TMD."

December 18, 2012 - Temporomandibular Joints in Asymptomatic and Symptomatic Nonpatient Volunteers: A Prospective 15-year Follow-up Clinical and MR Imaging Study

"Volunteers with mild symptoms had a prevalence of disk displacement of the same magnitude as that reported in patients, although most volunteers, symptomatic as well as asymptomatic, maintained their TMJ status during 15 years."

December 4, 2012 - Evaluation of orofacial function in temporomandibular disorder patients after low-level laser therapy

"Results. There was a significant increase in the pressure pain threshold of the examined muscles. Mandibular movements were significantly improved in all patients. There was also a significant decrease in pain by palpation after laser exposure. However, no significant change was found in the maximum bite force, occlusal contact area or occlusal pressure after the treatment and also the values after the treatment were still significantly lower than those of the healthy individuals. Conclusion. This particular type of LLLT is effective at relieving pain but does not provide physical improvement."

December 2012 - Morphology of the Temporomandibular Joint (TMJ) of Sheep (Ovis aries)

"The results showed that the sheep is an excellent experimental model for the study of condylar growth, with and without the use of functional appliances, because of similarity in anatomy related to size, shape and position of the condyle to that of human beings. Thus, it is concluded that the study will help future investigators in the field of dentistry to consider the sheep as an experimental animal for further research."

November 27, 2012 - Analgesic and Sedative Effects of Melatonin in Temporomandibular Disorders: A Double-Blind, Randomized, Parallel-Group, Placebo-Controlled Study

"This study provides additional evidence supporting the analgesic effects of melatonin on pain scores and analgesic consumption in patients with mild-to-moderate chronic myofascial TMD pain. Furthermore, melatonin improves sleep quality but its effect on pain appears to be independent of changes in sleep quality."

October 24, 2012 - Inflammation of temporomandibular joint increases neural activity in rat vestibular nucleus

"A team of Korean researchers decided to see if the vestibular nuclei were affected in cases of jaw inflammation by means of simulating TMD in animal models. The team used two groups of rats. One group was injected with an inflammatory agent in the right TMJ. The other was a control group injected in the right TMJ with normal saline. They waited 24 hours and then studied neural activity in the vestibular nuclei. Sure enough, they noted signs of increased activity in the vestibular nuclei on both sides in both the experimental and control groups, but much greater activity in the nuclei of the experimental animals on the inflamed jaw side provide grounds for suspecting that symptoms of dizziness might well reflect abnormal vestibular activity as a result of TMJ inflammation."

October 2012 - Kinesiographic recordings of jaw movements are not accurate to detect magnetic resonance-diagnosed temporomandibular joint (TMJ) effusion and disk displacement: findings from a validation study.

"The findings do not support the usefulness of jaw-tracking devices in dental practices that diagnose and manage temporomandibular disorders."

October 2012 - Relationship Between Temporomandibular Disorders, Widespread Palpation Tenderness, and Multiple Pain Conditions: A Case-Control Study

"TMD subjects with widespread body palpation tenderness (WPT) experience a greater level of multiple comorbid pain conditions, compared to TMD subjects without WPT and non-TMD controls. Integration of bodily pain assessments can be informative for evaluation, diagnosis, and management of TMD."

September 24, 2012 - Dysfunctional pain inhibition in patients with chronic whiplash-associated disorders: an experimental study

"The present study demonstrates a lack of endogenous pain inhibitory pathways, and in particularly conditioned pain modulation, in patients with chronic whiplash–associated disorders (WAD), and hence provides additional evidence for the presence of central sensitization in chronic WAD."

September 9, 2012 - Temporomandibular joint pain: Analyzing discussions in online forums

"Internet posts in online discussion forums, in which patients with TMJ request information, are important sources of knowledge, because they reflect the feelings, concerns, and interpretations of those affected in an unadulterated form. Users participating in the ensuing discussion threads may be expected to offer not only empathy but also concrete proposals for further action. However, the recommendations made are not always reliable. Statements on the etiology and prognosis of the disorder are highly problematic, as they embody concepts that reinforce fear and contribute to a chronic outlook. It would therefore be highly desirable for professional societies or organizations to offer high-quality patient information on the web. This information should be regularly updated to reflect the current therapies available."

Summer 2012 - Does hypoxia-reperfusion injury occur in osteoarthritis of the temporomandibular joint?

"There is no evidence to support or reject the hypothesis that hypoxia reperfusion occurs in TMJ OA, and limited evidence is provided to support that hypoxia-reperfusion injury occurs in OA of the knee joint. Since the studies suggest differences between OA and other types of arthritis in relation to hypoxia-reperfusion mechanisms, further research in this field needs to distinguish OA from other types of arthritis."

August 2, 2012 - Overlap between functional GI disorders and other functional syndromes: what are the underlying mechanisms?

"The objective of this review is to discuss the proposed pathophysiologic mechanisms, which have been similarly studied in these conditions. These mechanisms include enhanced pain perception, altered regional brain activation, infectious etiologies, dysregulations in immune and neuroendocrine function, and genetic susceptibility. Studies suggest that these functional disorders are multifactorial, but factors which increase the vulnerability of developing these conditions are shared."

August 2, 2012 - Response properties of temporomandibular joint mechanosensitive neurons in the trigeminal sensory complex of the rabbit

"Based on these results, we conclude that sensory information is processed by TMJ neurons encoding at least joint position and displacement in the physiological range of mandibular displacement."

July 19, 2012 - Efficacy of stabilization splint treatment on temporomandibular disorders

"The findings of this study did not show that stabilization splint treatment in combination with counselling and masticatory muscle exercises has additional benefit in relieving facial pain and increasing the mobility of the mandible than counselling and masticatory muscle exercises alone in a short time-interval."

July 2012 - Are Temporomandibular Disorders and Tinnitus Associated?

"The current study aimed to research the prevalence of temporomandibular disorders (TMD) in patients with subjective tinnitus, as compared to controls, and the association between symptoms of TMD, tinnitus, and chronic pain. Two hundred patients were divided into two groups, according to the presence (experimental) or not (control) of subjective tinnitus. The subgroups were determined according to the RDC/TMD criteria. The Pain Pressure Threshold (PPT) values of the masseter and temporalis muscles were recorded bilaterally, and a Visual Analog Scale (VAS) was used to address subjective pain. The most prevalent TMD subgroups in the tinnitus patients (p<0.05) were myofascial pain with limited opening (39.0%), disc displacement with reduction (44.33%), and arthralgia (53.54%). The severity of tinnitus was significantly associated with the severity of chronic pain (p=.000). The PPT values were lower (p>0.05), while the Visual Analog Scale (VAS) was statistically higher (p=.000) for the tinnitus patients. These results suggest that an association exists between TMD and subjective tinnitus."

June 19, 2012 - Modulation of temporomandibular joint nociception and inflammation in male rats after administering a physiological concentration of 17β-oestradiol

"Similar to females, male rats with TMJ inflammation showed a reduced nociceptive response after treatment with a physiological concentration of oestradiol suggesting the effects of oestradiol treatment were not constrained by organizational processes in the males."

June 19, 2012 - Temporomandibular Joint Disorder Complaints in Tinnitus: Further Hints for a Putative Tinnitus Subtype

"Replicating previous work in tinnitus patients with TMJ complaints, classical risk factors for tinnitus like older age and male gender are less relevant in tinnitus patients with TMJ complaints. By demonstrating group differences for modulation of tinnitus by movements and sounds our data further support the notion that tinnitus with TMJ complaints represents a subgroup of tinnitus with clinical features that are highly relevant for specific therapeutic management."

June 7, 2012 - 5-HT induces temporomandibular joint nociception in rats through the local release of inflammatory mediators and activation of local β adrenoceptors

"The 5-hydroxytryptamine (serotonin, 5-HT) is an important inflammatory mediator found in high levels in the synovial fluid of the temporomandibular joint (TMJ) of patients with inflammatory pain. In this study, we used the nociceptive behavior responses, measured as flinching the head and rubbing the orofacial region, as a nociceptive assay. We demonstrated that the local blockade of the 5-HT(3) receptor and β(1) or β(2)-adrenoceptors, the depletion of norepinephrine in the sympathetic terminals and the local inhibition of cyclooxygenase significantly reduced 5-HT-induced TMJ nociception. These results demonstrated that 5-HT induces nociception in the TMJ region by the activation of β(1) and β(2) adrenoceptors located in the TMJ region and local release of sympathetic amines and prostaglandins. Therefore, the high levels of 5-HT in the synovial fluid of patients with TMJ inflammatory pain may contribute to TMJ pain by similar mechanisms."

June 2012 - Biopsychosocial Factors Associated with the Subcategories of Acute Tempormandibular Joint Disorders

"Participants with multiple diagnoses reported higher pain, as well as other symptoms, relative to participants without a TMD diagnosis. For chewing performance, participants with mutual diagnoses reported more pain compared to other participants. Finally, the risk-status of patients significantly affected chewing performance."

May 28, 2012 - White matter brain and trigeminal nerve abnormalities in temporomandibular disorder

"Temporomandibular disorder (TMD) is a prevalent chronic pain disorder that remains poorly understood. Recent imaging studies reported functional and gray matter abnormalities in brain areas implicated in sensorimotor, modulatory, and cognitive function in TMD, but it is not known whether there are white matter (WM) abnormalities along the trigeminal nerve (CNV) or in the brain. Here, we used diffusion tensor imaging, and found that, compared to healthy controls, TMD patients had 1) lower fractional anisotropy (FA) in both CNVs; 2) a negative correlation between FA of the right CNV and pain duration; and 3) diffuse abnormalities in the microstructure of WM tracts related to sensory, motor, cognitive, and pain functions, with a highly significant focal abnormality in the corpus callosum. Using probabilistic tractography, we found that the corpus callosum in patients had a higher connection probability to the frontal pole, and a lower connection probability to the dorsolateral prefrontal cortex, compared to controls. Finally, we found that 1) FA in tracts adjacent to the ventrolateral prefrontal cortex and tracts coursing through the thalamus negatively correlated with pain intensity; 2) FA in the internal capsule negatively correlated with pain intensity and unpleasantness; and 3) decreases in brain FA were associated with increases in mean diffusivity and radial diffusivity, markers of inflammation and oedema. These data provide novel evidence for CNV microstructural abnormalities that may be caused by increased nociceptive activity, accompanied by abnormalities along central WM pathways in TMD."

May 22, 2012 - How to investigate and treat: migraine in patients with temporomandibular disorders

"The authors briefly discuss the clinical commonalities of migraine and temporomandibular disorders (TMD), and the differential diagnosis of these conditions with other causes of facial pain. They close by presenting the experience in the treatment of patients with the comorbidity."

May 15, 2012 - Craniofacial Pain and Jaw-muscle Activity during Sleep

"This short–term observational study suggests that there are no major differences between patients with different craniofacial pain conditions and pain–free individuals in terms of jaw–muscle electromyographic (EMG) activity recorded with a single–channel EMG device during sleep. However, some associations may exist between the level of EMG activity and various parameters of craniofacial pain. Longitudinal studies are warranted to further explore the relationship between sleep bruxism and craniofacial pain."

May 7, 2012 - Temporomandibular disorders, facial pain, and headaches

"Headaches and facial pain are common in the general population. In many cases, facial pain can be resultant from temporomandibular joint disorders. Studies have identified an association between headaches and temporomandibular joint disorders suggesting the possibility of shared pathophysiologic mechanisms of these 2 maladies. The aim of this paper is to elucidate potential commonalities of these disorders and to provide a brief overview of an examination protocol that may benefit the headache clinician in daily practice."

May 3, 2012 - Expression and localization of aquaporin-1 in temporomandibular joint disc with internal derangement

"Background:  Internal derangement is the most frequent arthropathy affecting the temporomandibular joint, where its commonest form is anterior disc displacement with or without reduction. Despite the frequency of the disorder, the biochemical features of displaced discs are still unclear. Methods:  We investigated the expression pattern and localization of aquaporin-1, an important channel protein involved in plasma membrane water permeability, in patients with anterior disc displacement (both with and without reduction), with a view to assessing the characteristics of local tissue responses to the microenvironmental changes induced by abnormal mechanical loading of the displaced disc. Protein expression was studied by immunohistochemistry in different areas of discs from 18 patients with anterior disc displacement with or without reduction and in four normal controls. Results:  A greater proportion of cells immunopositive for aquaporin-1 were detected in diseased than in normal discs. Whereas protein expression was substantially similar in the different areas of normal discs, a significantly larger number of immunopositive cells were detected in the posterior band of displaced discs without reduction and in the anterior and intermediate bands of those with reduction. Conclusions:  These findings suggest that aquaporin-1 is expressed and upregulated in temporomandibular joint with anterior disc displacement (both with and without reduction)."

May 2, 2012 - Hippocampal Nerve Growth Factor Potentiated by 17β-Estradiol and Involved in Allodynia of Inflamed TMJ in Rat

"The hippocampus is believed to play an important role in sex-based differences of pain perception. Whether estrogen potentiates allodynia in the inflamed temporomandibular joint (TMJ) through affecting the expressions of pain-related genes in the hippocampus remains largely unknown. Because the nerve growth factor (NGF) is an important gene related to inflammatory pain, we tested whether hippocampal NGF may be involved in TMJ inflammatory pain. Here we showed that the rat hippocampal NGF was upregulated by TMJ inflammation induced by complete Freund adjuvant. NGF upregulation was further potentiated by estradiol in a dose-dependent manner. In contrast, NGF transcription in the amygdala, prefrontal cortex, and thalamus was not affected by TMJ inflammation and estradiol. An intrahippocampal injection of NGF antibody or NGF receptor inhibitor K252a (inhibitor for tropomyosin receptor kinase A, TrkA) reduced the allodynia of inflamed TMJ in proestrous rats. Our data suggest that the hippocampal NGF is involved in estradiol-sensitized allodynia of inflammatory TMJ pain."

May 2012 - Implementing gnathological and neuromuscular concepts in patients with chronic migraine

"Temporomandibular disorders are among the potential comorbidities of migraine, and recent reports showed that they may have a role in promoting its progression into chronic migraine (CM). In order to clarify the possible role of neuromuscular components of the stomatognathic system in patients with CM, we studied 18 patients admitted as inpatients at our Headache Unit to undergo a withdrawal protocol for medication overuse, who underwent orthosis, after clinical and instrumental gnathological evaluation. They were subsequently evaluated after 6 months. The values of electromyographic parameters as well as of pain outcomes showed a significant decrease after orthosis. The implementation of gnathological and neuromuscular concepts can have a relevant role in the management of CM patients, in the contest of a multidisciplinary approach."

April 27, 2012 - Sustained Inflammation Induces Degeneration of the Temporomandibular Joint

"The findings are consistent with the hypothesis that sustained TMJ inflammation, even within the presently observed 35 days, may be a predisposing factor for structural abnormalities. Insight into TMJ inflammation and degeneration is anticipated to improve the understanding of the pathogenesis of TMJ arthritis and help design clinically relevant strategies for tissue engineering."

April 27, 2012 - Temporomandibular Disorders, Facial Pain, and Headaches

"Headaches and facial pain are common in the general population. In many cases, facial pain can be resultant from temporomandibular joint disorders. Studies have identified an association between headaches and temporomandibular joint disorders suggesting the possibility of shared pathophysiologic mechanisms of these 2 maladies. The aim of this paper is to elucidate potential commonalities of these disorders and to provide a brief overview of an examination protocol that may benefit the headache clinician in daily practice."

April 19, 2012 - Dental occlusion, body posture and temporomandibular disorders: where we are now and where we are heading for

"There is no evidence for the existence of a predictable relationship between occlusal and postural features, and it is clear that the presence of temporomandibular disorders (TMD) pain is not related with the existence of measurable occluso–postural abnormalities. Therefore, the use instruments and techniques aiming to measure purported occlusal, electromyographic, kinesiographic or posturographic abnormalities cannot be justified in the evidence–based TMD practice."

April 18, 2012 - Interventions for the management of temporomandibular joint osteoarthritis

"In view of the paucity of high level evidence for the effectiveness of interventions for the management of TMJ OA, small parallel group RCTs which include participants with a clear diagnosis of TMJ OA should be encouraged and especially studies evaluating some of the possible surgical interventions."

April 13, 2012 - The dental occlusion as a suspected cause for TMDs: epidemiological and etiological considerations

"Symptom improvement after insertion of an oral splint or after occlusal adjustment does not prove an occlusal aetiology either, because the amelioration may be due to the change of the appliance–induced intermaxillary relationship. In addition, symptoms often abate even in the absence of therapy. Although patients with a TMD history might have a specific risk for developing TMD signs, it appears more rewarding to focus on non–occlusal features that are known to have a potential for the predisposition, initiation or perpetuation of TMDs."

April 1, 2012 - Electromyography in diagnosing temporomandibular disorders

"The authors of this systematic review found no evidence to support the use of EMG for the diagnosis of TMD."

March 28, 2012 - Alterations in intermediate filaments expression in disc cells from the rat temporomandibular joint following exposure to continuous compressive force

"These findings indicate that the mature articular cells are capable of producing desmin instead of the other intermediate filaments against mechanical stress. The desmin-positive disc cells lacked α-smooth muscle actin (α-SMA) in this study, even though desmin usually co-exists with α-SMA in the vascular smooth muscle cells or pericytes. Because the precursor of a pericyte has such an immunoexpression pattern during angiogenesis, there is a further possibility that the formation of new vessels commenced in response to the extraordinary compressive force."

March 23, 2012 - Randomized Controlled Trial on Physical Therapy for TMJ Closed Lock

"The interaction between time and treatment group was not significant. Hence, physical therapy had no significant additional effect in patients with anterior disc displacement, without reduction, of the temporomandibular joint."

March 23, 2012 - Signs and symptoms of temporomandibular dysfunction in fibromyalgic patients

"Thus, there is a high prevalence of signs and symptoms of TMD in FM patients, indicating the need for an integrated diagnosis and treatment of these patients, which suggest that the FM could be a medium- or long-term risk factor for the development of TMD."

March 8, 2012 - Chronic pain and weather conditions in patients suffering from temporomandibular disorders: a pilot study

"The analyses suggest the existence of different interindividual responses to climatic changes. However, the identified putative role of meteorological variables and of their two–way interactions suggests that further investigations on larger samples may be useful to assess the research question under examination."

March 2012 - Acupuncture may be no more Effective than Sham Acupuncture in Treating Temporomandibular Joint Disorders

"There is no evidence to show that acupuncture is an effective treatment for Temporomandibular joint dysfunction (TMJD). The few existing randomised controlled trials (RCTs) are of poor methodological quality."

February 10, 2012 - Spry1 and Spry2 Are Essential for Development of the Temporomandibular Joint

"Findings demonstrate the importance of regulated RTK signaling during TMJ development and suggest multiple skeletal origins for the fossa. Notably, our work provides the evidence that the TMJ condyle and disc develop independently of the mandibular fossa."

February 8, 2012 - No Evidence to Support the Effectiveness of Low-Level Laser Therapy for Treatment of Temporomandibular Disorders

"The authors concluded currently, there is no evidence to support the effectiveness of Low-level laser therapy in the treatment of TMD."

February 8, 2012 - Randomized Controlled Trial on Physical Therapy for TMJ Closed Lock

"The study demonstrated a significant positive effect of informing and instructing patients with anterior disc displacement without reduction. Physical therapy did not have an additional effect. The results confirmed that, in most patients, the natural course of TMJ closed lock is benign and self-limiting, probably because of the adaptive capacity of the structures involved. A conservative approach of providing information and instruction, therefore is warranted."

January 2012 - Effect of gonadal steroid hormones on formalin-induced temporomandibular joint inflammation

"Findings demonstrate a pronounced anti-inflammatory effect of estradiol and testosterone in the temporomandibular joint region and suggest that this effect may mediate, at least in part, the antinociceptive effect of these hormones."

January 2012 - Evaluation of the Short-term Effectiveness of Education versus an Occlusal Splint for the Treatment of Myofascial Pain of the Jaw Muscles

"During a short period, education was slightly more effective than an occlusal splint delivered without education in reducing spontaneous muscle pain in patients with TMD. Pain-free mouth opening, headache and pain during chewing were not significantly different between the two treatments."

January 2012 - Patients With Temporomandibular Disorders Have Increased Fatigability of the Cervical Extensor Muscles

"In this study, muscle activity was analyzed electromyographically in healthy controls, patients with myogenous (muscle) TMD and those with mixed (muscle and joint) TMD while performing a muscle endurance test. The results showed that the cervical muscles fatigued more quickly in the TMD patients than in the control subjects. Thus, such patients may develop neck and shoulder pain more easily than normal persons."

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