Role of psycho-social factor in the etiology of the temporomandibular disorders: relevance of a bi-axial diagnosis.

AIM: The prevalence of temporomandibular disorders (TMD) is higher among women than men, indicating a multifactorial role for gender-related differences in the etiology of TMD: physiological hormonal differences, inflammatory response to stress, and sociocultural differences in response to pain. The aim of this study was to draw a biobehavioral picture of the TMD patient based on Research Diagnostic Criteria for TMD (RDC/TM) Axis II diagnosis and analysis of gender-related differences. METHODS: Between January 2006 and January 2008, 362 subjects were consecutively enrolled from patients who presented at the Clinic for Temporomandibular Disorders, School of Dental Medicine, University of Pavia, because of orofacial pain, limitation or joint sounds on mandibular movement. Of the 362 subjects evaluated, 308 met the inclusion criteria. RESULTS: The average age of the study population was 41 years; the female: male ratio was 4:1. When stratified according to chronic pain intensity grade and gender, 26% of the women had grade I, 36.4% grade II, 17% grade III, and 9.7% grade IV; 34.4% of the men had grade I, 32.8% grade II, 6.5% grade III, and 3.3% grade IV. Depression was moderate in 35 women and in 6 men and severe in 138 women and in 24 men; somatization was moderate in 59 women and in 20 men and severe in 143 women and in 19 men. CONCLUSIONS: Gender-related differences may be considered risk factors for TMD; psychological characteristics, including somatization, depression, and anxiety related to gender, appear to have a significant impact on the prevalence of TMD.