In a clinical study conducted in 1986 on 100 patients, we were able to demonstrate that intubation leads to the occurrence of temporary disturbances of the stomatognathic system. To verify these results, a double-blind study was conducted involving 140 patients of ASA groups I and II. Further acceptance criteria were: operation outside of the head and neck area, no throat pack or gastric tube, and the requirement of dental antagonists on the left and right side. Group composition: Group A: oral intubation with a laryngoscope (n = 50); Group B: nasal intubation using a fiberoptic endoscope (n = 40); Group C: face mask (n = 50) Groups A and B were divided at random. Balanced anesthesia was performed for all patients. In group B, after nasal intubation the mandible was placed and fixed in the habitual occlusion position. The patients had a dental examination preoperatively and on 1st, 2nd and 3rd postoperative day. Parallel to this study, we also interviewed 400 patients after routine intubation anesthesia with regard to postoperative temporomandibular joint (TMJ) symptoms. Groups A, B, and C were comparable in age, sex, height, weight, preoperative values of maximal mandibular movement, and pathological findings of the TMJ (Tables 1-3); the only differences were a longer mean duration of surgery in groups A and B than in group C (P greater than 0.05) and that women described more stomatognathic disorders in the preoperative medical history than men.(ABSTRACT TRUNCATED AT 250 WORDS)