Abstract: A filler member for use in molding a dental model in a dental impression formed in a mold carried in a mandibular dental impression tray. The tray has a u-shaped trough formed by inner and outer u-shaped walls joined by a bottom wall. The inner wall defines a lingual space. The filler member is made from shape-retaining material with a smooth surface and is shaped to fill at least the upper portion of the lingual space in the impression tray when placed therein. The filler member is placed in the lingual space in a manner to prevent model forming material, used in molding the model, from entering the lingual space on the tray from the upper portion of the tray.