Methods of determining centric relation: a comparative study

To minimize neuromuscular adaptations, the centric relation established in reconstructive dentistry should ideally represent the anterior-superior, non-laterally displaced position of the condyles in the glenoid fossa. In 35 healthy volunteers without temporomandibular dysfunction, the Jaw Motion Analyzer (JMA) jaw-tracking system was used to measure the spatial coordinates of defined condylar and incisal points during manual guidance in the posterior-superior direction and during fast and slow closure movements (neuromuscular techniques), and to compare these positions with those measured during physiological jaw-closing movement ending in intercuspal position (ICP). At small incisal edge distances, condylar displacement relative to ICP was approximately 0.3 mm in the posterior-superior direction with manual guidance, and about 0.3 mm in the anterior-superior direction during the neuromuscular techniques. With large incisal edge distances, the neuromuscular techniques resulted in anterior displacement of the condyles in an anterior-superior position against the slopes of the articular eminences; in contrast, condylar position remained relatively stable with posterior-superior guidance. In summary, it can be concluded that, at small incisal edge distances, the neuromuscular techniques resulted in an anterior-superior orientation of the condyles in the glenoid fossa. This corresponds to the idealized notion of an anterior- superior physiological condylar position. Keywords: methods of determining centric relation, centric relation recording, reliability of methods of determining centric relation