Influence of choice of reference point on the condylar movement paths during mandibular movements

Series of four open-close, protrusive and lateral movements were recorded by the six degrees of freedom jaw movement recording system OKAS-3D in 20 healthy subjects. Consequently the movement paths of nine condylar points, the palpated lateral pole and eight points located on a square parallel to the sagittal plane with an edge of 10 mm and centred around the lateral pole were calculated. For all movements except the protrusive movements, the 3-D excursions of the condylar points strongly depended upon the choice of condylar reference point (ANOVA, P < 0.001). During laterotrusive movements the Bennett angle and the Bennett shift also varied significantly according to the position of the reference point (ANOVA, P < 0.001). The results of this study underline that comparison of condylar movements between different studies is only possible when the same condylar reference point is used. General consensus on the choice of condylar reference point is thus needed.