A tray-shaped dental treatment device includes a moisture-resistant barrier layer having a front side wall and a bottom wall, and a dental treatment composition. In addition, the tray-shaped dental treatment device includes at least one of the following anatomical features to enhance the fit of the device: (1) the bottom wall includes a plurality of cuts positioned to help the bottom wall better conform to abrupt changes in the diameters of a person's teeth where the bicuspids and canines meet, or (2) the bottom wall includes at least one V-shaped or U-shaped indentation configured to be inserted into the depression typically found along the top surfaces of a person's molars, or (3) the front side wall and bottom wall include radii of curvature that account for typical flaring of a patient's incisors.