[Investigation of related risk factors of temporomandibular disorders in 109 patients].

TMD has a higher prevalence in female than in male, with a peak incidence in 20-29 age group. Habits of bruxism or clenching, unilateral mastication and maxillofacial injury history may be risk factors of TMD, while life stress, habits of stay-up late, chewing hard food and orthodontic treatments show no significant correlation with TMD.