1 New Method Determining the Vertical Dimension of Rest for Completely Edentulous Patient -Using the Letter Mohammed M. Fuad* ABSTRACT: Determination of the correct VDO for an edentulous patient is generally agreed to be one of the most important steps in making a complete denture. One of the current methods for observing the interocclusal distance is to observe the distance between the occlusal surfaces during speech, with the Frankfort plane parallel with the floor. The aim of this work is to evaluate the arabic letter as a speaking method for determining the vertical dimension for completely edentulous patient. Twenty healthy completely edentulous male patients were selected for this study. The vertical dimension determined by the new physiologic speaking method using the letter was compared to the vertical dimension of occlusion determined by the physiologic swallowing method regarding the mean interarch distance (IAD) of each method. From results of this study, It was found that the difference between the mean interarch distance (IAD) of the two methods was within the free way space. It can be concluded that, the new physiologic speaking method using the letter may be considered as a simple, practical and scientific method for establishing the vertical dimension of rest. INTRODUCTION: Determining the vertical dimension of occlusion is a critical procedure for a totally or partially edentulous patient (Toolson and Smith, 2006). Determination of the correct VDO for an edentulous patient is generally agreed to be one of the most important steps in making a complete denture (Bissasu, 2001). It has been found that the greatest cause of full denture difficulties is the failure to duplicate the normal vertical dimension (Meyer, 2001). There are two vertical dimensions: vertical dimension of rest and vertical dimension of occlusion. According to Glossary of Prosthodontic Terms (1999), the following definitions should be mentioned: Rest vertical dimension: The distance between two selected points measured when the mandible is in the rest physiologic position. Occlusal vertical dimension: The distance measured between two points when the occluding members are in contact. The difference between the vertical dimension of rest and the vertical dimension while in occlusion *Lecturer of prosthodontics, Faculty of Dentistry Mansoura University