Oral jaw behaviors in TMD and bruxism: a comparison study by severity of bruxism.

The purpose of this study was to document the prevalence of oral jaw behaviors concomitant to bruxism in TMD+bruxing behavior patients and in nonbruxer controls. Clinical examination, questionnaires, and specific criteria to allocate patients to mild, moderate, and severe groups of TMD and bruxers were used. The sample consisted of 274 TMD+bruxing behavior patients and 52 control non-bruxing behavior groups evaluated at the Center for the Study of TMD. The mean age of the TMD+bruxing behavior group was about 33.11 years old (range 16.66, SD = 11.52) as compared to 34.90 years old (range 17-67, SD = 14.26) in the control group. Oral jaw behaviors were assessed in the mild, moderate, and severe TMD+bruxing groups, and in the corresponding control group. It was found that the prevalence of oral jaw behaviors was higher in the TMD+bruxing behavior group as compared to the control. Hence, concomitant oral jaw behaviors predominated in bruxers and increased with its severity. The data reinforce the need to assess TMD patients in terms of the presence of bruxism, its severity, and concomitant oral jaw habits. Such approach will enable the clinician to have better understanding about the role of these behaviors in TMD. Epidemiological data was also provided regarding jutting the jaw forward (a rarely-described oral jaw habit) in a relatively large sample of TMD+bruxing patients, suggesting a more clinical intervention in children and adolescents. This study is the first to document the prevalence of specific oral jaw habits in a relatively large sample of TMD+bruxing behavior classified by degree of severity. Results suggest that TMD+bruxing patients may present many other additional oral jaw habits which may concur to increase masticatory muscle activity thus leading to TMD signs and symptoms. Factors responsible for the increased frequency of oral jaw habits with the severity of bruxism behavior remain unknown and therefore further studies are needed.