Tooth whitening enamel layer may also be gradually thinned or even perforated by the various forms of tooth wear. Teeth may be darkened by a buildup of surface stains (extrinsic staining), which hides the natural tooth color; or the tooth itself may discolor (intrinsic staining). Extrinsic stains can become internalised through enamel defects or cracks or as a result of dentine becoming exposed but most extrinsic stains appear to be deposited on or in the dental pellicle. Causes of extrinsic staining include: Changes in the thickness of the dental hard tissues would result in intrinsic discolouration. There are a few causal factors
Human tooth development appliances, an area of bone under compressive force from a tooth moving toward it has a high osteoclast level, resulting in bone resorption. An area of bone receiving tension from periodontal ligaments attached to a tooth moving away from it has a high number of osteoblasts, resulting in bone formation. Thus, the tooth or teeth are slowly moved along the jaw so as to achieve a dentition that works in harmony. In this way, the width of the space between the alveoli and the root is kept about the same. The connection between the gingiva and the tooth is called