Determination of occlusal vertical dimension: a literature review. 
The vertical dimension of occlusion refers to the length of the face as determined by the amount of separation of the jaws.  Its determination is important for fabrication of all restorations.  Many techniques have been used for measurement of the vertical dimension of occlusion in dentulous and edentulous patients.  These range from using preextraction records to the use of swallowing, functionally acquired jaw positions associated with phonetics, and cephalometric radiographs and evaluation of radiopaque paste in the vestibular fornix.  There is no universally accepted or completely accurate method of determining the vertical dimension of occlusion in edentulous patients.  There seem to be no significant advantages of one technique other than those of cost, time, and equipment requirements.  It is the end result that matters.  It should be satisfactory to the dentist and the patient from an esthetic point of view and not induce degenerative changes from a functional standpoint.  Regardless of the technique, the vertical dimension of occlusion must be determined carefully by the dentist for a successful prosthesis.