Zsigmondy System
Palmer notation is a system used by dentists to associate information to a specific tooth.
It was originally termed the Zsigmondy system after the Austrian dentist Adolf Zsigmondy who developed the idea in 1861, using a Zsigmondy cross to record quadrants of tooth positions.[2]. Adult teeth were numbered 1 to 8, and the child primary dentition (also called deciduous, milk or baby teeth) were depicted with a quadrant grid using Roman numerals I, II, III, IV, V to number the teeth from the midline. Palmer changed this to A, B, C, D, E. This makes it less confusing and less prone to errors in interpretation.
The Palmer notation consists of a symbol (?? ??) designating in which quadrant the tooth is found and a number indicating the position from the midline. Adult teeth are numbered 1 to 8, with deciduous (baby) teeth indicated by a letter A to E. Hence the left and right maxillary central incisor would have the same number, “1″, but the right one would have the symbol, “?”, underneath it, while the left one would have, “?”. -Source