Tooth whitening the human eye and brain. Teeth are composed of a surface enamel layer, which is whiter and semitransparent, and an underlying dentin layer, which is darker and less transparent. These are calcified, hard tissues comparable to bone. The natural shade of teeth is best considered as such; an off-white, bone-color rather than pure white. Public opinion of what is normal tooth shade tends to be distorted. Portrayals of cosmetically enhanced teeth are common in the media. In one report, the most common tooth shade in the general population ranged from A1 to A3 on the VITA classical A1-D4 shade guide.
Human tooth ligaments attached to a tooth moving away from it has a high number of osteoblasts, resulting in bone formation. The gingiva ("gums") is the mucosal tissue that overlays the jaws. There are three different types of epithelium associated with the gingiva: gingival, junctional, and sulcular epithelium. These three types form from a mass of epithelial cells known as the epithelial cuff between the tooth and the mouth. The gingival epithelium is not associated directly with tooth attachment and is visible in the mouth. The junctional epithelium, composed of the basal lamina and hemidesmosomes, forms an attachment to the tooth. The