Most common method to establish occlusal vertical dimension
(i) Niswonger’s method (physiologic rest position) 
This is the most commonly used method to establish occlusal vertical dimension. It uses the physiologic rest position (vertical dimension at rest) to determine the occlusal vertical dimension. As discussed previously in this chapter, Niswonger stated that:
VD at Occlusion = VD at rest – freeway space (2–4 mm)
Hence, the physiologic rest position is first determined. The contoured maxillary occlusal rim is placed in the patient’s mouth and the vertical dimension at rest is determined using facial measurements as discussed previously. The mandibular occlusal rim is then inserted and it is trimmed and contoured until it meets the maxillary rim evenly. The lower rim is adjusted till the facial measurement in occlusion is 2–4 mm less than that in rest position. This will provide for the necessary interocclusal space or freeway space. The same can be verified, by asking the patient to part the lips without moving the jaws at rest position, with the occlusal rims inserted.
Niswonger’s method
Neuromuscular perception
Phonetics
None of the above