Sodium tripolyphosphate (STPP)

Most tooth surface stains consist of tightly linked proteins, carbohydrates and calcium. Whitening agents help remove tooth surface stains either by physical interaction or by chemical interaction with the stain components. An example of physical stain removal is using a polishing agent with higher abrasivity, like DCPA or DCPD. An example of chemical stain removal involves the use of sodium tripolyphosphate (STPP), which is effective by complexing (chelating) the calcium component of the stain. Other whitening agents used in toothpastes include certain enzymes and oxidizing agents.