Abstract: This invention relates to a dental impression tray having a U-shaped rim that can be positioned about the upper teeth of a patient. The upper posterior end of the impression tray is closed by a dam made of a preferably pliable material. Openings are provided in the U-shaped rim to permit the escape of hardenable material that may be placed under pressure as the dentist moves the impression tray into proper position in order to obtain the necessary impression of the upper teeth. The dam prevents unwanted posterior flow of the hardenable material into the throat of a patient.