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Facebow (Dental)

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Dental Equipment & Materials Dental Glossary

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Facebow (Dental)

A facebow is a caliper-like instrument used in dentistry to record the three-dimensional spatial relationship between the maxillary arch and the temporomandibular joints (TMJs), then transfer that relationship to a dental articulator so that mounted casts accurately simulate the patient’s jaw movement.

How a Facebow Works

The device is positioned on the patient’s face using two condylar rods seated at or near the ear canals, approximating the transverse hinge axis of the TMJs. A bite fork — attached to the occlusal surfaces of the upper teeth — captures the arch position in three-dimensional space, while an anterior reference point (typically the infraorbital notch or nasion) establishes a horizontal reference plane. The assembled record is then locked and carried to a semi-adjustable or fully adjustable articulator, where it guides the precise mounting of maxillary dental casts.

Key Components

  • Condylar rods (ear pieces) — locate the approximate transverse hinge axis near the TMJs
  • Bite fork — registers the three-dimensional position of the upper dental arch
  • Orbital pointer or nasion relator — establishes the anterior reference plane, commonly the Frankfurt horizontal
  • Locking mechanism — secures the completed record for stable articulator transfer

Clinical Significance

Without a facebow transfer, casts mounted on an articulator rely on assumed average measurements, which can introduce cumulative errors into the final restoration. Facebow records are especially important in cases involving changes to the vertical dimension of occlusion, full-mouth reconstruction, or the management of temporomandibular disorders where the condylar position relative to centric relation must be precisely controlled.

Two types are used in clinical practice:

  • Arbitrary facebow — locates the transverse hinge axis by estimated anatomical landmarks; faster and widely used for routine restorative cases
  • Kinematic facebow — precisely identifies the true hinge axis through a series of mandibular movements; more accurate and reserved for complex full-mouth rehabilitations

Accurate facebow technique is a foundational step in restorative dentistry — even small errors in recording upper arch position can compound through the fabrication process and ultimately compromise occlusal harmony in the finished restoration.