(Open access funding provided by Semmelweis University)
In the temporomandibular joint two separate movements of rotation and translation
occur in two articular spaces during mouth opening. Over the years, the approach has
changed considerably, but it is still subject to controversy as to which of these
movement is involved in the initial stage of mouth opening. In the present study,
the extent of rotation and translation was investigated in the first 5 mm of mouth
opening.The study was carried out on 46 volunteers. Anamnesis was taken and patients
were examined. For the investigation, an ultrasonic digital motion analyser (KaVo
Arcus Digma 2) was applied. The measurements were made after calibration to an arbitrary
axis. Each participant performed three open-close movements in succession, starting
from maximum intercuspal position.Data were statistically processed using cubic spline
interpolation. Linear regression was then used. The resulting line is significantly
(p < 0.0001) different from the horizontal that represents only rotational movement.The
results show that during mouth opening from maximum intercuspal position, translation
is present continuously in addition to rotation. Therefore, it might be time to re-evaluate
the principle of a pure rotational approach.
