Objective: to determine the prevalence of parafunctional habits and bruxism among patients with TMD.
Subjects and methods: 292 patients with TMD (according to RDC/TMD) were examined at the Head Institute of the Federal University of São Paulo, according to the definition of parafunctional habit as being a disordered or fixed perverted function or having become constant practice established by frequent repetition. The study period was from October/2001 to June/2002. Females comprised 84%, and males 16%, with age ranging from 9 to 90. The patients were classified into four groups as follows: Group 1-presence of parafunctional habits, Group 2- presence of bruxism, Group 3- presence of parafunctional habits and bruxism, Group 4- absence of parafunctional habits and bruxism. In addition, patients from Groups 1 and 3 were classified according to type and number of oral habits presented.
Results: 87 patients presented parafunctional habits (30%, Group 1), 37 presented only bruxism (13%, group 2), 107 presented both parafunctional habits and bruxism (37%, Group 3), and 61 presented neither parafunctional habits nor bruxism (21%, Group 4). Among the parafunctional habits detected, diurnal clenching habit, present in 194 patients, was the most common, followed by onycophagia (45 patients), chewing habit (41 patients), lip biting (17 patients), tongue biting (15 patients), and others (22 patients). Bruxism was observed in 144 patients. The majority of patients (125) presented only one parafunction, whereas 51 patients presented 2 habits and 18 patients presented 3 or more habits.
Conclusion: There is a high prevalence (79%) of parafunction and/or bruxism among patients with TMD, diurnal clenching habit being the most prevalent type of parafunction. The recognition of these aspects, allowing correct diagnosis and guidance of treatment for TMD, is emphasized with the present study.