The Gerber Dynamic Facebow is used to trace the sagittal condylar path and to transfer the relation between the patient's occlusal plane and the condyles to the Condylator-articulator. Adjustable telescopic arms of the Facebow allow the setting vertically and horizontally. Retractable writing point holders are positioned against the marked condylar buccal eminence on the patient's cheek. Horizontal rods are indicating the occlusal plane. Adjusted or unadjusted Facebow is placed-in on to the Facebow's Stand. Facebow’s Stand is to mount the casts into the Condylator in correct relation to the TMJs according to the individually adjusted Facebow.
Measurement of the sagittal condylar path angle Gerber Dynamic Facebow acts as a caliper to record the relationship between the position of the mandibular condyles being attached to the mandible. Two writing points, wich are adjusted to the condyle-buccal eminence positions will trace mandible protrusive movements on a Registration card.
The positions of the right and left condyle's buccal eminence are to be found by palpation or in difficult cases by measuremants about 13mm in front of the external auditory meatus, on the ear-orbital line. The Facebow is slid onto the lower Transfer plate (No.106). Its telescopic arms are set. The writing points are opposite the marked condyle's buccal eminence. A Registration card is placed between a writing point and the surface of the patient's cheek. The patient is asked to protrude his mandible. The writing point follows the condyle and records the path onto the card. Two or three tracings are made for each condyle. The Facebow is removed from the patient and fixed to its stand to secure it's adjusted positions. Condyle sagittal path inclination The angle of the sagittal condylar path is determined on the Registration card with a protractor. The correction factor should be calculated. For each 1mm of opening between the incisors half a degree should be added to the measured angle indicated on the Registration cards. This calculated inclination is used to set the angle of the sagittal condylar paths onto the Condylator. Mounting the models Mounting the lower model: The adjusted Facebow with Transfer plate (No. 106) is fixed to its stand. The model is firmly connected to the lower Transfer plate by means of registration keys. The two writing points have to be closest to the center of the lateral Condylator double cones. The horizontal rods are parallel to the surface of the bench. A plaster-key has to be made mounting the lower model to the Condylator. As soon as the plaster is set the Facebow is carefully disconnected from the Transfer plate. The Facebow is now no longer required. Fixing the upper model: The lower model is mounted to the Condylator. The upper and lower models have to be connected by the registration keys as a result of the intraoral registration. A plaster-key has to be made mounting the upper model to the Condylator.