RESUMEN
This study was aimed at clarifying the functional role of the patient to delineate this step through two recognized positions: the first was deeply breathing, and the second was the head flexion. Ten patients were selected with no apparent undercuts and medium viscous saliva to obtain a more detailed, reliable ZOE impression, which was further functionally corrected with wax. After its calibration, the retentive measuring device was used to measure the displacing force for both comparable functional impressions. It could be clearly seen from the results of this study that forces needed to displace the upper impression while establishing posterior palatal seal were considered. When the patient is breathing deeply, this displacing force was less than that when the patient flexing the head