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La douleur est un probleme de sante publique et constitue le premier motif de consultation medicale. La prise en charge de la douleur est une obligation legale, ethique et technique. Si les douleurs aigues sont bien maitrisees par les specialistes de la sphere orofaciale, le traitement des douleurs chroniques reste plus complexe. Dans tous les cas, la demarche du praticien consistera a evaluer le type de douleur concerne en fonction de la comprehension des mecanismes sousjacents et a decider s’il prend la responsabilite du traitement ou s’il oriente le malade vers une consultation specialisee.L’optimisation de la prise en charge necessite l’organisation des structures de soins, de la recherche fondamentale et clinique et de la qualite de l’enseignement initial et de la formation continue.

This short review focuses on the main properties of the nervous system responsible for pain originating from oral, nasal and pharyngeal cavities. First, the major roles of the somatic sensations coming from the orofacial and pharyngeal areas are emphasized. Then, the description of the respective peripheral fields of the different cranial nerves involved in these somatic sensations is followed by the description of the primary afferent neurons and the central nuclei and pathways. The review emphasizes that pain does not result from a simple transmission of nervous impulses that would follow a fixed "hardwire" pathway but, on the contrary, results from an ever-changing balance between excitatory and inhibitory influences. These descending influences and other mechanisms may lead acute pain to become chronic through plastic changes of the nervous system and possible neuropathic changes. Finally, certain psychosocial factors that may facilitate chronic pain arousal are discussed.

Stomatodynia is characterised by a spontaneous burning pain in the oral mucosa without known cause or recognised treatment. The purpose of this double-blind, randomised, multicentre parallel group study was to evaluate the efficacy of the topical use of clonazepam. Forty-eight patients (4 men and 44 women, aged 65±2.1 years) were included, of whom 41 completed the study. The patients were instructed to suck a tablet of 1 mg of either clonazepam or placebo and hold their saliva near the pain sites in the mouth without swallowing for 3 min and then to spit. This protocol was repeated three times a day for 14 days. The intensity was evaluated by a 11-point numerical scale before the first administration and then after 14 days. Two weeks after the beginning of treatment, the decrease in pain scores was 2.4±0.6 and 0.6±0.4 in the clonazepam and placebo group, respectively ( P =0.014). Similar effects were obtained in an intent-to-treat analysis ( P =0.027). The blood concentration of clonazepam was similar whether it was measured 14 days after sucking a tablet three times a day or during the 5 h that followed sucking a single tablet ( n =5). It is hypothesised that clonazepam acts locally to disrupt the mechanism(s) underlying stomatodynia.

Temporomandibular disorders (TMD) are a significant public health problem affecting approximately 5% to 12% of the population.1 TMD is the second most common musculoskeletal condition (after chronic low back pain) resulting in pain and disability.1 Pain-related TMD can impact the individual's daily activities, psychosocial functioning, and quality of life. Overall, the annual TMD management cost in the USA, not including imaging, has doubled in the last decade to $4 billion.1 Patients often seek consultation with dentists for their TMD, especially for pain-related TMD. Diagnostic criteria for TMD with simple, clear, reliable, and valid operational definitions for the history, examination, and imaging procedures are needed to render physical diagnoses in both clinical and research settings. In addition, biobehavioral assessment of pain-related behavior and psychosocial functioning—an essential part of the diagnostic process—is required and provides the minimal information whereby one can determine whether the patient's pain disorder, especially when chronic, warrants further multidisciplinary assessment. Taken together, a new dual-axis Diagnostic Criteria for TMD (DC/TMD) will provide evidence-based criteria for the clinician to use when assessing patients, and will facilitate communication regarding consultations, referrals, and prognosis.2 The research community benefits from the ability to use well-defined and clinically relevant characteristics associated with the phenotype in order to facilitate more generalizable research. When clinicians and researchers use the same criteria, taxonomy, and nomenclature, then clinical questions and experience can be more easily transferred into relevant research questions, and research findings are more accessible to clinicians to better diagnose and manage their patients. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) have been the most widely employed diagnostic protocol for TMD research since its publication in 1992.3 This classification system was based on the biopsychosocial model of pain4 that included an Axis I physical assessment, using reliable and well-operationalized diagnostic criteria, and an Axis II assessment of psychosocial status and pain-related disability. The intent was to simultaneously provide a physical diagnosis and identify other relevant characteristics of the patient that could influence the expression and thus management of their TMD. Indeed, the longer the pain persists, the greater the potential for emergence and amplification of cognitive, psychosocial, and behavioral risk factors, with resultant enhanced pain sensitivity, greater likelihood of additional pain persistence, and reduced probability of success from standard treatments.5 The RDC/TMD (1992) was intended to be only a first step toward improved TMD classification, and the authors stated the need for future investigation of the accuracy of the Axis I diagnostic algorithms in terms of reliability and criterion validity—the latter involving the use of credible reference standard diagnoses. Also recommended was further assessment of the clinical utility of the Axis II instruments. The original RDC/TMD Axis I physical diagnoses have content validity based on the critical review by experts of the published diagnostic approach in use at that time and were tested using population-based epidemiologic data.6 Subsequently, a multicenter study showed that, for the most common TMD, the original RDC/TMD diagnoses exhibited sufficient reliability for clinical use.7 While the validity of the individual RDC/TMD diagnoses has been extensively investigated, assessment of the criterion validity for the complete spectrum of RDC/TMD diagnoses had been absent until recently.8 For the original RDC/TMD Axis II instruments, good evidence for their reliability and validity for measuring psychosocial status and pain-related disability already existed when the classification system was published.9–13 Subsequently, a variety of studies have demonstrated the significance and utility of the original RDC/TMD biobehavioral measures in such areas as predicting outcomes of clinical trials, escalation from acute to chronic pain, and experimental laboratory settings.14–20 Other studies have shown that the original RDC/TMD biobehavioral measures are incomplete in terms of prediction of disease course.21–23 The overall utility of the biobehavioral measures in routine clinical settings has, however, yet to be demonstrated, in part because most studies have to date focused on Axis I diagnoses rather than Axis II biobehavioral factors.24 The aims of this article are to present the evidence-based new Axis I and Axis II DC/TMD to be used in both clinical and research settings, as well as present the processes related to their development.

There is no current consensus on the taxonomy of the different forms of idiopathic orofacial pain (stomatodynia, atypical odontalgia, atypical facial pain, facial arthromyalgia), which are sometimes considered as separate entities and sometimes grouped together. In the present prospective multicentric study, we used a systematic approach to help to place these different painful syndromes in the general classification of chronic facial pain. This multicenter study was carried out on 245 consecutive patients presenting with chronic facial pain (>4 months duration). Each patient was seen by two experts who proposed a diagnosis, administered a 111-item questionnaire and filled out a standardized 68-item examination form. Statistical processing included univariate analysis and several forms of multidimensional analysis. Migraines (n=37), tension-type headache (n=26), post-traumatic neuralgia (n=20) and trigeminal neuralgia (n=13) tended to cluster independently. When signs and symptoms describing topographic features were not included in the list of variables, the idiopathic orofacial pain patients tended to cluster in a single group. Inside this large cluster, only stomatodynia (n=42) emerged as a distinct homogenous subgroup. In contrast, facial arthromyalgia (n=46) and an entity formed with atypical facial pain (n=25) and atypical odontalgia (n=13) could only be individualised by variables reflecting topographical characteristics. These data provide grounds for an evidence-based classification of idiopathic facial pain entities and indicate that the current sub-classification of these syndromes relies primarily on the topography of the symptoms.