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mise à jour du
6 mai 2004
J Oral Rehabilitation
Clinical TMD, pain related disability and psychological status of TMD patients
Yap A, Cha E, Hoe K
Faculty of dentistry, University, Singapore
Bâillements et stomatologie


Introduction : Temporomandibular disorders (TMD) is a collective term embracing a number of clinical problems that involve the masticatory musculature, the temporomandibular joint or both. TMD have been identified as a major cause of non-dental pain in the oro-facial region and have been considered to be a subclassification of musculoskeletal disorders. Cross-sectional epidemiological studies in specific populations have shown that about 75% have at least one sign of joint dysfunction (joint sound, joint tenderness, etc.) and about 33% have at least one symptom (face pain, joint pain, etc.). Although once viewed as a single syndrome, current research supports the view that TMD are a group of related disorders that may have many common feature. The most frequent presenting symptom is pain, usually localized in the muscles of mastication, the pre-auricular area and/or the temporomandibular joint, which is aggravated by jaw functions like chewing and yawning.
The precise aetiology and mechanism of TMD is still poorly understood and remains the centre of much debate and controversy. This controversy has been fuelled in part by the lack of standardized diagnostic criteria for defining clinical TMD subtypes and uniformity in research protocols/designs. A project to create research diagnostic criteria for TMD was undertaken at the University of Washington to redress this lack. The efforts of this project yielded a set of research diagnostic criteria (RDC), labelled 'RDC/TMD' that allows for standardization and replication of research into the most common forms of muscle and joint related TMD. Research diagnostic criteria/temperomandinular disorders (RDC/TMD) is divided into two axes. Axis 1 involves the clinical TMD conditions and Axis 2 the pain-related disability and psychological status. This two-axis approach enables physical diagnosis to be co-ordinated with operationalized assessment of psychological distress and psychosocial dysfunction associated with chronic TMD and oro-facial disability. Currently, the RDC/TiMD is administered via pen-and-paper. The data collected is then entered manually and batch processed by a mainframe statistical package to obtain Axis 1 diagnosis and Axis 2 profiles. A time lag between patient history taking/clinical examination and the generation of diagnoses is thus inevitable. As knowledge of the patient's psychological status is important for the initial management of TMD, the time lag required for the generation of the Axis 2 profile is not beneficial.
The current project investigated the clinical TMD, pain-related disability and psychological status of TMD patients using a computer-aided TMD diagnostic systern (NUS TMD vl-1) developed by the National University of Singapore. This diagnostic system aimed to address the current deficit of the RDC/TMD and provided on-line real-time Axis 1 and 2 diagnosis/ profiles and database construction for research on TMD. The relationship between limitations related to mandibular functioning (LRMF) scores and graded chronic pain severity/depression status and the association between clinical TMD and Axis II non-specific pain items were also investigated.[...]
Discussion : The RDC/TMD is offered for research purposes and is, of necessity, based more on a description of observable findings that appear to cluster together than on underlying àetiological mechanisms. It deals with only the most common forms of TMD as they manifest themselves in adults and encompasses TMD conditions for which there is information of sufficient reliability and validity to develop working case definitions using physical examination and interview procedures. Some of the less common conditions excluded from RDC/ TMD include ankylosis, aplasia or hyperplasia, contracture or hypertrophy and neoplasms.
About 13,1% of patients experienced myofascial pain and 7,5% experienced myofascial pain with limited opening. Patients with myofascial pain were significantly more distressed by headaches than patients with no muscle disorders. Headaches are a very common finding, especially in patients with TMD. Several studies have found that subjects suffering from headaches have a higher frequency of tenderness in the TMJ and muscles of masticatio. In the present study, patients with TMJ pain were not significantly distressed by headaches compared with those without TMJ pain. Difference in patient types and the low incidence of arthralgia and osteoarthritis in the present may account for the difference observed.
The results of the present study lend some support to the view that recurrent headaches should be considered as part of the symptom panorama in patients with TMD. Conversely, examination of the masticatory system should be included in the medical diagnosis of all headache sufferers. The association of headache and TMD has been further strengthened by the positive results of headache from different types of prosthetic and orthotic treatment aimed at correcting TMD. More cross -disciplinary research is warranted in this area. It was also observed that patients suffering from myofascial pain with limited opening were significantly less distressed by soreness of muscles than those with myofascial pain without limited opening. This may be explained in part by the fact that those with limited opening were inclined to restrict their mandibular movements and functions compared with those who were not limited. The majority of patients (> 80%) did not suffer from disc displacements and joint conditions. The low incidence of osteoarthritis/osteoarthrosis may be accounted for by RDC/TMD's use of only coarse crepitus in making these diagnoses and the lack of correlation to tomograms. Findings concur with several epidemiological studies which showed the higher incidence of muscle disorders compared with disc displacements and joint tenderness. No significant difference in distress levels from the various non-specific pain items was observed between the patients with the different Group2 (disc displacements) and 3 (otherjoint conditions) diagnosis.
Depression and anxiety related to major life events might alter patient's perception of and tolerance for physical symptoms causing them to seek treatment. There is evidence that some TMD patients experience more anxiety than do healthy control groups. The plethora of emotional and interpersonal connotations associated with the functions of the jaw and mouth makes these anatomical sites the ideal focus for symbolic portrayal of psychological conflicts. For some TMD patients, these symptoms are somatic metaphors that express and resolve pre-existing or concurrent psychological conflicts.
Psychological factors had been implicated in several aspects of TMD. Firstly, stress-related muscle hyperactivity and oral habits had been suggested as aetiological factors. Secondly, psychological factors have been suggested to explain why some patients seem to be more bothered by symptoms and why a small percentage of patients with symptoms actually seek treatment. Finally, psychological conditions such as depression and secondary gain have been used to explain why some patients do net respond to conventional therapy. About 38% of the population examined in the present study was moderately to severely depressed. Patients with mild depression was not determined as the current SCL-90-R Depression Scale does not provide for it and no raw mean scale scores for mild depression are currently availabre. Results lend support to the clinician's view that TMD patients are 'psychologically different'. It is therefore essential that psychological factors, if present, be identified early in the initial management of TMD as failure to do so may result in treatment non-success and worsening of the patient's condition. On-line reporting of pain-related disability and psychological status is the greatest advantage of this computer-aided diagnostic system as this information, which is usually not available to TMD clinicians, is crucial in the management of TMD patients.
Patients who were moderately or severely depressed were significantly more distressed by headaches, nausea or upset stomach and general soreness of muscles compared with normal patients. In addition, severely depressed patients were also more distressed by heart or chest and lower back pain than normal and moderately depressed patients. Dworkin et al. (1990) assessed multiple pain conditions and their association with affective disturbance, somatization and psychological distress based on the questionnaire data from 1016 members of a large health maintenance organization. Respondents were asked about the presence of the same five pain conditions investigated in this study and were classified empirically in terms of dysfunctional chronic pain status based on pain severity, pain persistence and pain-related disability. They concluded that the number of pain conditions reported was a better predictor of major depression than were measures of pain experience, including pain severity and persistence. The results of the present study support their hypothesis.
The majority of patients (78-5%) had low disability with almost equal distribution between low (Grade I) and high (Grade Il) intensity. The results from an earlier pilot study of a different patient pool were similar (78,3% with low disability). As only 4,7% of patients had high disability that was moderately limiting (Grade III) and none had high disability that was severely limiting (Grade IV), it can be concluded that disability associated with TMD is generally low. There was no significant difference in graded chronic pain severity between normal and depressed patients.
The jaw disability checklist was used to assess the extent to which TMD interferes with the activities specifically related to mandibular function. The three most frequent jaw disabilities were: eating hard foods (77,6%), yawning (75,7%) and chewing (64,5%). These disabilities were all classical symptoms used for the screening of TMD. Limitations related to mandibular functioning scores were computed by calculating the number of positive responses and dividing this by the number of items answered. The mean LRMF scores corresponded to the graded chronic pain severity. Ranking of LRMF scores were as follows: grade IV > grade III > grade Il > grade I > Grade 0. Patients who were moderately and severely depressed also had higher LRMF scores than normal patients. No statistically significant difference in LRMF scores was, however, observed between normal/depressed patients and between patients with the different graded chronic pain severity classification. An extension of the present study, involving more TMD patients, is currently being undertaken. This is necessary before any conclusive results pertaining to clinical TMD, pain-related disability and psychological status of TMD patients can be drawn.
Conclusions : The clinical TMD, pain-related disability and psychological status of 107 TMD patients were investigated using a computer-aided diagnostic system (NUS TMD vl-1). About 20,6% of the patients had myofascial pain but only 7,5% experienced limited mandibular opening associated with myofascial pain. The majority of patients (>80%) did not suffer from disc displacements (right and left joints). The frequency of arthralgia was also low (right joint 8,4%; left joint 7,5%) and only one patient had osteoarthosis of the TMJ. About 78,5% of the patients had low disability with almost equal distribution between low and high intensity pain. About 27,1% of the patients were moderately depressed and 11,2% had severe depression. No significant difference in LRMF scores was observed between normal/depressed patients and between patients with the different graded chronic pain severity classification. The three most frequent jaw disabilities are: eating hard foods (77,6%), yawning (75,7%) and chewing (64,5%). NUS TMD vl-1 is an extremely useful tool in the diagnosis/research of clinical TMD.