• Pain intensity (German Pain Questionnaire; Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)) [ Time Frame: Pre-Post-Design including 4 assessment points: pre-treatment, post-treatment, 3- and 6-month follow up ] [ Designated as safety issue: No ]
  

• Pain disability (Pain Disability Index; Jaw Disability List (RDC/TMD)) [ Time Frame: Pre-Post-Design including 4 assessment points: pre-treatment, post-treatment, 3- and 6-month follow up ] [ Designated as safety issue: No ]
  
• Somatoform symptoms (Screening for Somatoform Disorders) [ Time Frame: Pre-Post-Design including 4 assessment points: pre-treatment, post-treatment, 3- and 6-month follow up ] [ Designated as safety issue: Yes ]
  
• Psychopathology / Affect (Centers for Epidemiologic Studies Depression Scale) [ Time Frame: Pre-Post-Design including 4 assessment points: pre-treatment, post-treatment, 3- and 6-month follow up ] [ Designated as safety issue: No ]
  
• Cognitive variables (Illness Perception Questionnaire; Questionnaire for Assessment of Level of Coping with Pain) [ Time Frame: Pre-Post-Design including 4 assessment points: pre-treatment, post-treatment, 3- and 6-month follow up ] [ Designated as safety issue: No ]
  
• Nocturnal EMG masseter activity [ Time Frame: Pre-Post assessment ] [ Designated as safety issue: No ]
  

The purpose of this study is to develop and evaluate a biofeedback-based cognitive behavioral treatment for temporomandibular disorders using a randomized controlled design. 100 patients suffering from chronic temporomandibular disorder are diagnosed using Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Subsequently, patients are randomly assigned to either a psychological intervention receiving 8 sessions of biofeedback-based cognitive behavioral treatment or to a dental intervention receiving interocclusal splint therapy.

Assessment takes place at baseline, after treatment approximately 8 weeks later, 3 and 6 months follow up. The effects of the interventions are evaluated in terms of reduction in pain intensity, pain related disability, psychological variables such as somatoform symptoms, depression and pain related cognitive adjustment as well as nocturnal EMG activity.

Additionally, the study aims at identifying variables that predict treatment outcome. Further analyses include initial changes in treatment motivation and illness perceptions and its influence on treatment success, as well as changes in psychophysiological stress reactivity through treatment.