guide plane [ME, guiden, to guard; L, planum, level ground] , 1. a part of an orthodontic appliance that has an established inclined plane for changing the occlusal relation of the maxillary and mandibular teeth and for permitting their movement to normal positions. 2. a plane that is developed on the occlusal surfaces of occlusion rims for positioning the mandible in centric relation. 3. two or more parallel vertical surfaces of abutment teeth shaped to direct the path of placement and removal of a partial denture.
