The hinge axis reference used during maxillary mounting is determined during which procedure?

• A. Shade matching
• B. Bite registration
• C. Indirect retainer placement
• D. Facebow transfer

Answer: (D)

Transferring the patient's jaw relationships with a facebow transfer establishes the hinge axis reference during maxillary mounting. The facebow records how the upper jaw sits in relation to the condyles, allowing the articulator to be oriented so its hinge axis lines up with the patient’s true hinge axis. This alignment is crucial for accurately simulating jaw movements, especially in centric and eccentric positions, when the denture or crown prep is being finished. Shade matching, bite registration, and indirect retainer placement have important roles in other aspects of fabrication, but they do not establish the hinge axis orientation.