facebows

A facebow is a dental instrument used to record the spatial relationship of a patient’s maxillary arch to the skull. By capturing how the upper jaw sits relative to the cranial base, clinicians can mount a dental cast on an articulator in the same orientation as in the mouth, allowing more accurate simulation of jaw movements for prosthodontic, orthodontic, and restorative work.

A typical facebow comprises a bite fork that engages the upper teeth, a frame or bow that rests on the head or ears, and a transfer mechanism that relates the maxilla to a reference axis. The device is aligned with reference planes (often the Frankfort horizontal plane), and the resulting orientation is transferred to the articulator so the maxillary cast mirrors the patient’s intraoral position. Some designs use external auditory references, while others rely on indirect anatomical landmarks.

There are two main categories: arbitrary facebows and kinematic (true hinge-axis) facebows. Arbitrary facebows estimate the hinge axis from average landmarks and transfer the relation to a semi-adjustable articulator. Kinematic facebows locate the patient’s actual condylar hinge axis with a tracing device, providing a mounting based on the true hinge axis.

Facebows are used to improve occlusal accuracy in complex restorations, full-mouth rehabilitations, and cases requiring detailed condylar-path replication. Limitations include potential recording errors, practitioner technique, and patient cooperation. Digital technologies offer virtual mounting alternatives, but conventional facebows remain common in many clinics.