Facebow and Hinge Axis

A facebow is a caliper-like instrument used to record the spatial relationship of the maxillary arch to the hinge axis of the mandible and transfer it to an articulator, replicating jaw movements for accurate prosthesis fabrication. The hinge axis is an imaginary line around which the mandible rotates during the initial phase of opening. Accurate hinge axis recording ensures correct centric relation, occlusal harmony, and functional efficiency. Facebows are of two types: arbitrary, which approximate the hinge axis (within 5 mm accuracy), and kinematic, which locate the true hinge axis precisely. The facebow maintains the orientation of the occlusal plane, improves esthetics, and reduces intraoral adjustments. Modern digital facebows and virtual articulators now use 3D motion tracking and AI to enhance accuracy and workflow integration. Together, the facebow and hinge axis remain essential for achieving functional and esthetic success in prosthodontic rehabilitation.