A time for change of tooth numbering systems.

Tooth numbering provides dentists with an essential shortcut in clinical record-keeping. Today, three systems are favored worldwide: the Zsigmondy/Palmer system, the universal system, and the FDI two-digit system. Histories of these tooth numbering methods are traced, and the strengths and deficiencies of each are discussed. The FDI two-digit system-used throughout the world, but not in the USA-is the only method that makes visual sense, cognitive sense, and computer sense. It deserves consideration by American dentists as our official tooth numbering system.