The document discusses the history, causes, materials, and techniques of tooth bleaching. It begins with the earliest known uses of tooth whitening in the 1300s and progresses to modern techniques. The main causes of tooth discoloration discussed are extrinsic stains from foods/drinks and intrinsic stains from issues such as tetracycline use, fluorosis, and pulpal pathology. Common bleaching materials mentioned are hydrogen peroxide, carbamide peroxide, and sodium perborate. Techniques covered include in-office bleaching using these agents along with light activation, and home bleaching using custom-fitted night guards. Advantages and disadvantages are also briefly touched on.