Composition and methods that include potassium nitrate for whitening and / or reducing tooth sensitivity. The dental compositions may optionally include a dental bleaching agent, such as hydrogen peroxide or carbamide peroxide. The dental compositions may be applied directly to the person's teeth, or they may be loaded into a comfortable fitting, flexible, thin-walled dental tray and placed over the person's teeth. In that case, the dental compositions will include a tackifying agent, such as carboxypolymethylene, dispersed within a solvent, which assists the composition in retaining the dental tray over the person's teeth as a result of the adhesive properties of the dental composition rather than due to mechanical interlocking of the tray over the person's teeth. The dental compositions may further include anticariogenic and antimicrobial agents.