Prevalence of risk factors for temporomandibular disorders: a retrospective survey from 300 consecutive patients seeking care for TMD in a French dental school
PURPOSE: The purpose of this study was to observe the prevalence of the different diagnostic groups of TMD disorders (articular, muscular, and associated disorders) and the prevalence of the different TMD risk factors from a population of patients seeking specialized care in the TMD clinic at a public dental school. MATERIALS AND METHODS: Data were collected from the retrospective analysis of archival records of 500 consecutive new patients who attended the TMD clinic at the Dental School of Lyon, France, over a 4-year period. The diagnostic criteria were based on those defined by the American Academy of Orofacial Pain: articular disorders (TMJ pain, disc displacement with or without reduction, osteoarthritis and osteoarthrosis), masticatory and cervical muscle disorders, and associated symptoms (migraine/tension-type headache, tinnitus, dizziness). The diagnosis was mainly made based on clinical history and clinical examination of the patient performed by the same trained examiner. In addition, an oral questionnaire was submitted to each patient in order to list all potential risk factors for TMD which were classified into five groups: traumatic, oral parafunctions, psychologic, occlusal, and systemic. RESULTS: The selected population was composed of 300 patients including 232 females (77.3%) and 68 males (22.7%) corresponding to a female-to-male ratio of 3.4:1. Disc displacement with reduction (66.7% of the patients) and muscular tenderness/masseter hypertrophy (62.3%) were the two most prevalent TMD symptoms followed by masticatory myofacial pain (38%) and TMJ pain (29.6%). Associated disorders represented almost 9% of the symptoms, headache being the most prevalent one (14.3% of the patients). Oral parafunctions represented the most important risk factor group (n = 489, 36.9%) followed by traumatic factors (n = 354, 26.7%) and psychologic factors (n = 257, 19.4%). The weakest percentage was obtained for the occlusal factors (n = 57, 4.3%). When all risk factors are considered individually, the two most prevalent factors identified on this population were tooth clenching (77% of the patients) and self-reported stress (59.3%) followed by antecedents of extraction of wisdom teeth (34.3%), endotracheal intubation (30.7%), biting habits (29.3%), gum chewing (28%), and previous orthodontic treatment (28%). CONCLUSION: The results of this study emphasized the high prevalence of disc displacement with reduction and muscular tenderness to palpation among the TMD diagnostic groups and the high prevalence of tooth clenching and psychologic factors (stress) among the risk factors. It may be hypothesized that stress affects TMD symptoms by increasing clenching habits thus predisposing to disc displacement. This is supported by the results of a recent study which showed that daytime tooth clenching/grinding is a significant risk factor for myofacial pain and disc displacement (Michelotti et al., 2010). The prevention of tooth clenching appears to be an essential component of the treatment of temporomandibular disorders.