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A study of a small patient sample sought to assess the effects of head angulation on the vertical dimension of occlusion. In some patients, increasing the head angulations showed a positive tendency of displacement, whereas in others the displacements were negative. Most displacements were mixed and irregular. A mathematical analysis revealed no correlation and no significance in the relationship of displacement versus the progressive changes in head angulation. The tested hypothesis was that the vertical dimension of occlusion would increase (or progressively alter) as the angulation of the head was progressively increased. Twelve attempts failed to produce a recognizable and mathematically acceptable pattern of distortion. This experiment failed to support the widely held hypothesis that the patient should be seated in an upright position to prevent distortion of the recording of VDO. It appears that the best recommendation for patient posture during the establishment of the maxillomandibular relationship is one that is comfortable for the patient and is easy for the dentist to obtain the recording.

Twelve edentulous patients were evaluated for changes in facial contour and lip support when the head was progressively tilted backward. The mandibular facial contour changes did not occur in a progressive cause and effect type of relationship. A trend pattern could not be discerned. The maxillary facial contour did have a significant progressive cause and effect relationship in two of the 12 patients and was a positive relationship. As the angles were increased, the displacement of the maxillary facial contour increased anteriorly. The question as to why the maxillary facial contour had a significant progressive cause-and-effect relationship in two of the 12 patients and the mandibular facial contour did not remain unresolved. In a practical sense, it seems reasonable to establish the maxillomandibular relationship with the patient in a comfortable position. This and the ease of recording by the dentist are the primary considerations.