Deficient cytokine control modulates temporomandibular joint pain in rheumatoid arthritis

The aim was to investigate how endogenous cytokine control of tumor necrosis factor (TNF) influences temporomandibular joint (TMJ) pain in relation to the role of anti‐citrullinated peptide antibodies (ACPA) in patients with rheumatoid arthritis (RA). Twenty‐six consecutive patients with TMJ RA were included. Temporomandibular joint pain intensity was assessed at rest, on maximum mouth opening, on chewing, and on palpation. Mandibular movement capacity and degree of anterior open bite (a clinical sign of structural destruction of TMJ tissues) were also assessed. Systemic inflammatory activity was assessed using the Disease Activity Score in 28 joints (DAS28) for rheumatoid arthritis. Samples of TMJ synovial fluid and blood were obtained and analyzed for TNF, its soluble receptor, soluble TNF receptor II (TNFsRII), and ACPA. A high concentration of TNF in relation to the concentration of TNFsRII in TMJ synovial fluid was associated with TMJ pain on posterior palpation on maximum mouth opening. The ACPA concentration correlated significantly to the TNF concentration, but not to the TNFsRII concentration, indicating that increased inflammatory activity is mainly caused by an insufficient increase in anti‐inflammatory mediators. This study indicates that TMJ pain on palpation in patients with RA is related to a deficiency in local cytokine control that contributes to increased inflammatory activity, including sensitization to mechanical stimuli over the TMJ.     

Correlation between direction and severity of temporomandibular joint disc displacement and reduction ability during mouth opening

The most common temporomandibular joint (TMJ) internal derangement is an abnormal relationship of the disc with respect to the mandibular condyle, articular eminence and glenoid fossa‐disc displacement. The aim of our study was to analyse the correlation between partial/complete disc displacement in the intercuspal position (IP) and its reduction in the open‐mouth position (OMP) in both oblique sagittal and coronal planes on magnetic resonance imaging (MRI) in patients with temporomandibular disorders. Multisection MRI analysis of 382 TMJs was conducted in 191 patients with disc displacement according to the RDC/TMD criteria (148 women, 43 men; aged 14‐60 years). The disc position was evaluated on all oblique sagittal and coronal images in the IP and the OMP. Univariate logistic regression analysis showed that the severity of disc displacement in the sagittal plane is a statistically significant predictor of reduction ability during mouth opening (B = 3.118; P < .001). Moreover, the severity of disc displacement in both planes is also a significant predictor of disc reduction in OMP (B = 2.200; P < .05). In conclusion, reduction ability during mouth opening is associated with the severity of disc displacement in IP, in both sagittal and coronal planes. Multisection analysis of all MR images allows distinguishing the correct disc position from disc displacement and can improve the ability to distinguish between various stages of TMJ internal derangement.     

Synovectomy and diskectomy of the temporomandibular joint in patients with chronic arthritic disease compared with diskectomies in patients with internal derangement. A 3-year follow-up study

Twenty-five temporomandibular joints (TMJs) in 15 patients with chronic arthritic disease were treated with synovectomy and diskectomy. Twenty patients with internal derangement of 27 TMJs treated with diskectomy served as a control group. A response in pain relief was seen in 73% of the patients with chronic arthritic disease and in 80% of the patients with internal derangement 3 yr postoperatively. In both groups of patients a significant increase in mouth opening capacity and lateral movement of the mandible was seen postoperatively, with no significant difference in the improvement between the two groups. Four patients with chronic arthritic disease were reoperated within the 3-yr observation period. This study indicates that synovectomy and diskectomy of the TMJ may reduce pain and improve mandibular function in patients with severe chronic arthritic TMJ disease.     

Cytokines in healthy temporomandibular joint synovial fluid

Analysis of temporomandibular joint (TMJ) synovial fluid may elucidate the aetiology of temporomandibular disorders and arthritic conditions, as well as the inflammatory mechanisms involved. Knowledge about healthy synovial fluid is necessary to understand TMJ pathologies. We aimed to quantify the proinflammatory cytokines interleukin (IL)‐1β, IL‐2, IL‐6 and tumour necrosis factor (TNF), and the anti‐inflammatory cytokines IL‐10 and interferon (IFN)‐γ in healthy TMJ synovial fluid to serve as reference values for future studies on TMJ pathologies. Twenty healthy, young adult volunteers without temporomandibular dysfunction were included. Bilateral synovial fluid samples were obtained using the push‐pull technique with hydroxocobalamin described by Alstergren in 1999. Cytokines were quantified with Luminex multiplex assays and compared using nonparametric statistical analysis. No serious adverse effects were reported. Of 40 possible samples, 14 fulfilled the strict sampling criteria and were included in the analysis. Cytokine values (reported as medians with interquartile ranges) were as follows: TNF, 23 (13–37) pg mL^?1; IL‐2, 1·8 (0–22) pg mL^?1; and INF‐γ, 10 (0–47) pg mL^?1. IL‐1β, IL‐6 and IL‐10 were almost undetectable. In addition, TNF and INF‐γ cytokine levels correlated. We demonstrated that TNF was consistently detected and IFN‐γ and IL‐2 sporadically detected in the TMJ synovial fluid of healthy individuals using the hydroxocobalamin method and a multiplex assay. The cytokines IL‐10, IL‐1β and IL‐6 were barely detectable in this sample of healthy TMJs.     

Clinical outcomes of patients with bilateral anterior disc displacement without reduction and erosive change of the temporomandibular joint after performance of unilateral arthrocentesis and stabilisation splint therapy

The efficacy of a combination treatment of arthrocentesis and stabilisation splint for patients with bilateral anterior disc displacement without reduction (ADDWoR) and erosive change of the TMJ remains controversial. To evaluate clinical outcomes of patients with ADDWoR and erosive change of the TMJ after performance of unilateral arthrocentesis and stabilisation splint therapy. A retrospective study of 44 patients (37 females, 7 males, mean age of 34 years) with bilateral ADDWoR and erosive change of the TMJ were included in this study. Their clinical outcomes before and after arthrocentesis and stabilisation splint therapy were compared. Evaluation criteria were as follows: (a) Maximal mouth opening (MMO); (b) Right and left maximal lateral movement (RLM, LLM) and maximal protrusive movement (PM); (c) Visual analog scale (VAS) pain score during MMO, RLM, LLM and PM; and (d) VAS pain score during palpation of masticatory muscles. Wilcoxon signed-rank test, Mc Nemar test and paired t test were used for statistical analysis. Differences in VAS pain score between arthrocentesis and non-arthrocentesis sites were not statistically significant except MMO and LLM (P < .05) after 6 months. Differences in mean VAS pain scores for all variables between before arthrocentesis and 6 months follow-up in the arthrocentesis site were statistically significant. (P < .01). Unilateral arthrocentesis on more symptomatic TMJ and subsequent stabilisation splint therapy was highly successful for pain and achievement of normal range of mandibular movements in patients with both ADDWoR and bony change.     

Evaluation of the efficacy of different treatment modalities for painful temporomandibular disorders

The purpose of this study was to clinically evaluate the efficacies of three treatment methods and to compare their outcomes in patients with painful disc displacement. The study group comprised 45 patients with unilateral temporomandibular disorders who fell into Axis I group II (with limited mouth opening) of the Research Diagnostic Criteria for Temporomandibular Disorders. Magnetic resonance imaging was used for definitive diagnosis. The patients were divided randomly into three groups according to the treatment method: splint therapy, splint therapy with ultrasound-guided arthrocentesis, and splint therapy with low-level laser therapy. Patients were followed up after treatment for 6 months. The groups were compared in terms of pain and functional jaw movements (unassisted mouth opening without pain, maximum unassisted mouth opening, and contralateral movements). At the end of treatment, functional jaw movements were significantly increased while pain values were significantly decreased in all groups (P < 0.05). Group 2 had a quicker improvement in terms of mouth opening scores at the end of the first month, and unassisted mouth opening without pain was found to be more than 35 millimetres in all groups at the end of 6 months. All treatment modalities showed effective results on pain and functional jaw movements in the treatment of temporomandibular disorders.     

Effect of intra-articular corticosteroid injections on pain and mouth opening in juvenile idiopathic arthritis with temporomandibular involvement: A systematic review and meta-analysis

PurposeThe objective of this study was to investigate the effect of temporomandibular intra-articular corticosteroid injections (IACS) on pain and mouth opening in children with juvenile idiopathic arthritis (JIA) with temporomandibular joint (TMJ) involvement.MethodsSystematic review and meta-analysis methodology was used, beginning with a comprehensive literature search using MEDLINE, PubMed, EMBASE, Web of Science, and the Cochrane library. The population in question was pediatric patients with a JIA diagnosis and TMJ involvement; the intervention was IACS injections to treat TMJ arthritis; a strict control group was not considered necessary; the outcome was clinical signs of improvement of the TMJ arthritis based on pain and mouth opening capacity (MIO). Data on pain and MIO were extracted from the selected studies, and the methodological quality of studies was assessed according to the ROBINS-I tool. Results from the different studies were combined to calculate the pooled proportion with 95% confidence intervals (CIs) for pain resolution, and pooled mean differences with 95% CIs for improvement in MIO. Heterogeneity of the results among studies was tested using I² statistics.ResultsThe initial search yielded a total of 330 articles; 11 of these were selected for inclusion in the review. 325 participants were included from the combined studies, with the mean age of participants ranging from 5.3 to 13.6 years. Between 24 and 137 TMJs were selected for each of the studies. The pooled proportion of patients with pain resolution following IACS injection was 78% (95% CI: 59–90%), with large heterogeneity (I² = 62%). The pooled gain in MIO following IACS injection was 4.38 mm (95% CI: 2.76–6.00), also with high heterogeneity (I² = 67%).ConclusionsThe results suggest that in children diagnosed with JIA with TMJ involvement, IACS injections can help in reducing reported pain and improving mouth opening capacity, albeit with an important variation between studies.     

Jaw closing movement and sex differences in temporomandibular joint energy densities

Energy densities (ED, mJ/mm³) quantify mechanical work imposed on articular cartilages during function. This cross‐sectional study examined differences in temporomandibular joint (TMJ) ED during asymmetric versus symmetric jaw closing in healthy females versus males. ED component variables were tested for differences between and within sexes for two types of jaw closing. Seventeen female and 17 male subjects gave informed consent to participate. Diagnostic criteria for temporomandibular disorders and images (magnetic resonance (MR), computed tomography) were used to confirm healthy TMJ status. Numerical modelling predicted TMJ loads (F_normal) consequent to unilateral canine biting. Dynamic stereometry combined MR imaging and jaw‐tracking data to measure ED component variables during 10 trials of each type of jaw closing in each subject's TMJs. These data were then used to calculate TMJ ED during jaw closing asymmetrically and symmetrically. Paired and Student's t tests assessed ED between jaw closing movements and sexes, respectively. Multivariate data analyses assessed ED component variable differences between jaw closing movements and sexes (α = 0.05). Contralateral TMJ ED were 3.6‐fold and significantly larger (P < .0001) during asymmetric versus symmetric jaw closing, due to significantly larger (P ≤ .001) distances of TMJ stress‐field translation in asymmetric versus symmetric movement. During asymmetric jaw closing, contralateral TMJ ED were twofold and significantly larger (P = .036) in females versus males, due to 1.5‐fold and significantly smaller (P ≤ .010) TMJ disc cartilage volumes under stress fields in females versus males. These results suggest that in healthy individuals, asymmetric compared to symmetric jaw closure in females compared to males has higher TMJ mechanical fatigue liabilities.     

A clinical and MRI retrospective cohort study of patients with juvenile idiopathic arthritis (JIA) to determine if initial temporomandibular joint (TMJ) examination findings are associated with severity of TMJ arthritis

The purpose of the present study was to evaluate the association between initial TMJ examination findings and clinical and MRI severity of TMJ arthritis in a cohort of patients with JIA. The clinical variables were signs and symptoms at the initial TMJ evaluation. Outcome was the severity of TMJ arthritis as evaluated clinically by the Helkimo clinical dysfunction indices and by MRI. Associations of signs and symptoms with clinical and MRI severity were analyzed using a Fisher exact test and linear regression. The sample was composed of 101 patients with a mean age of 12.8 years, 76% of which were girls. Subjective difficulty in opening the mouth wide and objective limited MIO were the only clinical findings associated with both the severity of clinical dysfunction (p = 0.001 and p < 0.001, respectively) and the acute (p = 0.008 and p = 0.001, respectively) and chronic (p = 0.006 and p = 0.001, respectively) MRI severity of the TMJ arthritis. The results of this study suggest that in patients with JIA, limited mouth opening at the initial TMJ assessment may be a valid indicator of clinical severity of TMJ arthritis, which correlates with severity as seen on MRI.     

Impact of temporomandibular joint pain on activities of daily living in patients with rheumatoid arthritis

The aim of this study was to investigate the impact of temporomandibular joint (TMJ) pain on daily living in patients with rheumatoid arthritis (RA) involving the TMJ. Nineteen patients (17 F, 2 M) with a median (IQR) age of 44 (23) years were included. A scale for the influence of TMJ pain/discomfort on the activities of daily living was used. TMJ resting pain and pain upon maximum mouth opening according to a visual analog scale as well as pressure pain threshold and tenderness to digital palpation of the TMJ were assessed. Blood samples were collected to measure the level of acute phase proteins. Activities of daily living were influenced in all patients at different levels. The impact on daily living by TMJ pain/discomfort was greatest on the performance of physical exercises and jaw movements, while it was smallest on the performance of hobbies and eating. Pain during maximum mouth opening and tenderness to digital palpation were correlated to difficulties with several activities such as to yawn and open the mouth wide, while pressure pain threshold was correlated with difficulties during eating, which confirms that the pain was located in the TMJ. In conclusion, this study indicates that pain/discomfort from the TMJ in patients with RA has a significant negative impact on activities of daily living     

Impact of temporomandibular joint pain on activities of daily living in patients with rheumatoid arthritis

The aim of this study was to investigate the impact of temporomandibular joint (TMJ) pain on daily living in patients with rheumatoid arthritis (RA) involving the TMJ. Nineteen patients (17 F, 2 M) with a median (IQR) age of 44 (23) years were included. A scale for the influence of TMJ pain/discomfort on the activities of daily living was used. TMJ resting pain and pain upon maximum mouth opening according to a visual analog scale as well as pressure pain threshold and tenderness to digital palpation of the TMJ were assessed. Blood samples were collected to measure the level of acute phase proteins. Activities of daily living were influenced in all patients at different levels. The impact on daily living by TMJ pain/discomfort was greatest on the performance of physical exercises and jaw movements, while it was smallest on the performance of hobbies and eating. Pain during maximum mouth opening and tenderness to digital palpation were correlated to difficulties with several activities such as to yawn and open the mouth wide, while pressure pain threshold was correlated with difficulties during eating, which confirms that the pain was located in the TMJ. In conclusion, this study indicates that pain/discomfort from the TMJ in patients with RA has a significant negative impact on activities of daily living.     

Correlation of arthroscopic findings with clinical–radiological signs and symptoms of temporomandibular joint dysfunction: retrospective study of 829 joints

Temporomandibular joint (TMJ) arthroscopic findings are difficult to predict based on clinical criteria. Few studies have attempted to correlate signs, symptoms, and characteristics of patients with the final arthroscopic findings. The aim of this study was to assess the correlation between clinical–radiological signs and symptoms and arthroscopic findings in patients with TMJ dysfunction undergoing arthroscopy. A retrospective study was performed involving 487 patients (829 joints) with TMJ dysfunction who underwent TMJ arthroscopy between 2000 and 2019. The clinical–radiological variables recorded were pain, maximum mouth opening, joint noises, Wilkes classification, and disc displacement. The arthroscopic findings evaluated were synovitis, chondromalacia, adhesions, disc perforation, disc displacement, and roofing. Pain symptoms were significantly associated with the intensity of synovitis (P = 0.005) and disc displacement evaluated arthroscopically (P < 0.001). A statistically significant relationship was observed between Wilkes stage and the level of synovitis (P < 0.001) and chondromalacia (P < 0.001). Mouth opening was negatively correlated with adhesions (P < 0.001). Based on this study, pain symptomatology was associated with the intensity of synovitis and disc displacement evaluated arthroscopically, the Wilkes stage was a good predictor of the severity of synovitis and chondromalacia, and mouth opening was negatively correlated with adhesions.     

Differential diagnosis of jaw pain using informatics technology

This study aimed to deduce evidence‐based clinical clues that differentiate temporomandibular disorders (TMD)‐mimicking conditions from genuine TMD by text mining using natural language processing (NLP) and recursive partitioning. We compared the medical records of 29 patients diagnosed with TMD‐mimicking conditions and 290 patients diagnosed with genuine TMD. Chief complaints and medical histories were preprocessed via NLP to compare the frequency of word usage. In addition, recursive partitioning was used to deduce the optimal size of mouth opening, which could differentiate TMD‐mimicking from genuine TMD groups. The prevalence of TMD‐mimicking conditions was more evenly distributed across all age groups and showed a nearly equal gender ratio, which was significantly different from genuine TMD. TMD‐mimicking conditions were caused by inflammation, infection, hereditary disease and neoplasm. Patients with TMD‐mimicking conditions frequently used “mouth opening limitation” (P < .001), but less commonly used words such as “noise” (P < .001) and “temporomandibular joint” (P < .001) than patients with genuine TMD. A diagnostic classification tree on the basis of recursive partitioning suggested that 12.0 mm of comfortable mouth opening and 26.5 mm of maximum mouth opening were deduced as the most optimal mouth‐opening cutoff sizes. When the combined analyses were performed based on both the text mining and clinical examination data, the predictive performance of the model was 96.6% with 69.0% sensitivity and 99.3% specificity in predicting TMD‐mimicking conditions. In conclusion, this study showed that AI technology‐based methods could be applied in the field of differential diagnosis of orofacial pain disorders.     

Temporomandibular dysfunction post-craniotomy: Evaluation between pre- and post-operative status

ObjectiveTo identify risk factors associated with post-operative temporomandibular joint dysfunction after craniotomy.MethodsThe study sample included 24 patients, mean age of 37.3 ± 10 years; eligible for surgery for refractory epilepsy, evaluated according to RDC/TMD before and after surgery. The primary predictor was the time after the surgery. The primary outcome variable was maximal mouth opening. Other outcome variables were: disc displacement, bruxism, TMJ sound, TMJ pain, and pain associated to mandibular movements. Data analyses were performed using bivariate and multiple regression methods.ResultsThe maximal mouth opening was significantly reduced after surgery in all patients (p = 0.03). In the multiple regression model, time of evaluation and pre-operative bruxism were significantly (p < .05) associated with an increased risk for TMD post-surgery.ConclusionA significant correlation between surgery follow-up time and maximal opening mouth was found. Pre-operative bruxism was associated with increased risk for temporomandibular joint dysfunction after craniotomy.     

Outcome of eminectomy combined with discectomy and silastic interpositional graft for temporomandibular joint dysfunction: a retrospective study of 20 years

Internal derangement of the temporomandibular joint (TMJ) is usually treated conservatively, but about 5% require surgical treatment. We designed a retrospective study to assess the long-term outcomes of eminectomy combined with discectomy and silastic interpositional graft in 44 patients who had chronic TMJ dysfunction that had not responded to traditional conservative treatment and arthrocentesis. The maximum mouth opening, pain score, Wilkes stage, and clinical dysfunction index were measured before, and two years after, operation. All the patients showed significant improvement in mouth opening and reduced pain scores (p < 0.0001 in each case). There were no long-term operative complications, and postoperative magnetic resonance scans showed that the silastic interpositional graft was in a stable position with no evidence of degenerative changes on the surfaces of the joint and no lymphadenopathy.     

Efficacy of temporomandibular joint arthrocentesis with and without injection of sodium hyaluronate in treatment of internal derangements.

PURPOSE: This study was designed to investigate the efficacy of arthrocentesis with and without injection of sodium hyaluronate (SH) into the upper joint space in the treatment of temporomandibular joint (TMJ) internal derangements. PATIENTS AND METHODS: Forty-one TMJs in 5 males and 26 females aged 14 to 53 years comprised the study material. The patients' complaints were limited mouth opening, TMJ pain and tenderness, and joint noises during function. Patients were randomly divided into 2 groups in which only arthrocentesis was performed in 1 group and arthrocentesis plus intra-articular injection of sodium hyaluronate was performed in the other group. Both groups contained patients with disc displacement with reduction and with closed lock. Clinical evaluation of the patients was done before the procedure, immediately after the procedure, on postoperative day 1, and at 1, 2, 3, 4, 5, 6, 9, 12, 18, and 24 months postoperatively. Intensity of TMJ pain, jaw function, and clicking sounds in the TMJ were assessed using visual analog scales. Maximal mouth opening and lateral jaw movements also were recorded at each follow-up visit. RESULTS: Both techniques increased maximal mouth opening, lateral movements, and function, while reducing TMJ pain and noise. CONCLUSIONS: Although patients benefitted from both techniques, arthrocentesis with injection of SH seemed to be superior to arthrocentesis alone.     

Neuroendocrine, immune, and local responses related to temporomandibular disorders

Orofacial pain frequently originates from pathologic conditions in the masticatory muscles or temporomandibular joints (TMJs). The mediators and mechanisms that monitor pain and inflammation, centrally or peripherally, are of great interest in the search for new treatment modalities. The neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), and neuropeptide Y (NPY) have all been found at high levels in the synovial fluid of arthritic TMJs in association with spontaneous pain, while serotonin (5-HT) has been found in association with hyperalgesia/allodynia of the TMJ. Interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) have been found in arthritic TMJs, but not in healthy TMJs, in association with hyperalgesia/allodynia of the TMJ as well as spontaneous pain. Anterior open bite, which may be a clinical sign of TMJ destruction, has been found in association with high levels of CGRP, NPY, and IL-1 beta in the synovial fluid of the TMJ. Interleukin-1 beta has also been related to radiographic signs of joint destruction. Prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) are both present in the arthritic TMJ, and PGE2 has been shown to be associated with hyperalgesia/allodynia of the TMJ. Very little is known about pain and inflammatory mediators in muscles. However, we know that 5-HT and PGE2 are involved in the development of pain and hyperalgesia/allodynia of the masseter muscle in patients with fibromyalgia, whereas local myalgia (myofascial pain) seems to be modulated by other, as yet unknown mediators. Interaction between the peripheral nervous system (sensory and sympathetic nerves), the immune system, and local cells is probably of great importance for the modulation of pain and inflammation in the TMJ and orofacial musculature.     

Open versus closed treatment for unilateral mandibular extra-capsular condylar fractures: A meta-analysis

PurposeTo compare the functional outcomes between open reduction and internal fixation (ORIF) and closed reduction (CR) for unilateral mandibular extra-capsular condylar fractures in patients over 12 years old.Materials and methodsA comprehensive electronic search of PubMed, Embase and the Cochrane Library databases was conducted up to October 31, 2018. The evaluated functional outcomes included malocclusion, temporomandibular joint (TMJ) pain, protrusion, laterotrusion, maximum inter-incisal opening and lateral deviation during maximum inter-incisal opening.ResultsFourteen studies appeared to meet the inclusion criteria. Statistically significant differences between ORIF and CR treatment were observed for the outcomes of malocclusion (P = 0.001), maximum inter-incisal opening (P = 0.0008), lateral deviation during maximum inter-incisal opening (P = 0.007) and laterotrusion (P < 0.0001), but not for the outcomes of protrusion (P = 0.33) and TMJ pain (P = 0.29).ConclusionsORIF treatment of unilateral mandibular extra-capsular condylar fractures provides better functional outcomes in comparison to CR treatment with regard to occlusion, maximum inter-incisal opening, lateral deviation during maximum inter-incisal opening and laterotrusion, whereas there was no statistically significant difference between ORIF and CR group with regard to protrusion and TMJ pain.     

Prognostic factors in arthrocentesis of the temporomandibular joint: evaluation of 100 patients with internal derangement.

PURPOSE: The goal of this study was to analyze the prognostic factors for successful arthrocentesis for internal derangement (ID) of the temporomandibular joint (TMJ). PATIENTS AND METHODS: Arthrocentesis was carried out as the initial treatment in 103 TMJs of 100 patients with ID. The effectiveness of the treatment was evaluated in terms of the postoperative range of maximal mouth opening (MMO) and the degree of preoperative pain on a visual analog scale (VAS). Prognostic factors analyzed were age, sex, duration of painful locking, preoperative and postoperative range of MMO, preoperative degree of pain, preoperative clicking on opening mouth before becoming locked, and magnetic resonance imaging (MRI) findings. These factors were statistically analyzed. RESULTS: Seventy-three cases (71%) satisfied the criteria for success. One week after the procedure, the mean range of MMO in the successful cases (43.8 +/- 5.5 mm) was significantly greater than that in unsuccessful cases (36.9 +/- 6.6 mm) (P <.05). The mean preoperative degree of pain on a VAS in successful cases (4.7 +/- 2.9) was significantly smaller than that in unsuccessful cases (6.2 +/- 2.1) (P <.05). The preoperative incidence of morphologic changes in the mandibular condyle seen on MRI of successful cases was significantly less than that in unsuccessful cases (P <.05). CONCLUSION: Severe preoperative pain, relapse in the amount of mouth opening within 1 week after arthrocentesis, and preoperative bony changes in the condyle may be predictors of the effectiveness of arthrocentesis for ID of the TMJ.