NBDHE Review Questions: Quiz 189 March 17, 2016 by Hassan Shah When mandibular teeth are to be extracted, the patient should be positioned so that the occlusal plane of the mandibular arch is A. parallel to the floor when the mouth is wide open. B. perpendicular to the floor when the mouth is wide open. C. parallel to the floor when the teeth are closed together. D. perpendicular to the floor when the teeth are closed together. Δ