Dental bleaching compositions in the shape of a dental tray or tray-like form include a substantially solid adhesive layer and a dental bleaching gel. A barrier layer may be included on an outer surface of the adhesive layer to form a dental bleaching device. The adhesive layer comprises a substantially solid adhesive composition that has increased adhesiveness to oral tissue when moistened with saliva or water. The adhesive layer is formed from an intermediate composition that is heated to drive off the solvent. Using a bleaching gel separate from the adhesive layer improves the potency and stability of the bleaching agent, as the bleaching gel is not heated like the adhesive layer. The shape of the dental bleaching device facilitates placement of the device over a person's teeth with substantially less manipulation compared to the use of initially flat bleaching strips. The moistened adhesive composition reliably adheres the dental bleaching composition or device against a user's teeth during a bleaching procedure. Because a substantial portion of the adhesive composition remains solid or semi-solid during bleaching, the adhesive composition maintains a substantial portion of its adhesive properties and internal cohesive strength compared to, e.g., a bleaching gel used by itself.