Findings of mandibular movement and the position of the mandibular condyles during maximal mouth opening.

An investigation with respect to position of the mandibular condyles in relation to maximal vertical mouth opening was undertaken. For this purpose, 51 subjects of different nationalities were examined. None of the 51 persons had a TMJ disorder. The mobility of the mandible in different directions was clinically measured. With the use of two different reference lines (Methods A and B), the amount of the movement of the condyle from closed to maximal mouth opening position was measured in the sagittal plane on lateral tomograms. All of the measurements were recorded, and the means, SD, and range of variation were calculated. Statistical analysis was subsequently performed. The clinical results are comparable to those of other previous clinical studies. As seen in the lateral tomograms, the condyle in 41 out of 51 subjects moved beyond the articular eminence during maximal mouth opening. It was occasionally situated higher than the eminence. In only ten subjects, the condyle reached only the top of the articular eminence during maximal mouth opening. A moderate degree of dependency and correlation was found between maximal vertical movement of the mandible and the amount of movement of the right and left condyles from closed to maximal open position of the mouth, as seen in tomograms. None of our subjects had any sign of luxation despite the position of the condyle beyond the articular eminence with maximal mouth opening. Therefore, the diagnosis of condylar luxation cannot be established by radiologic investigation alone.