The specialty of orthodontics received a new impetus with the work of Angle. He organized and classified the various abnormalities of the teeth and jaws and devised many methods of treating them. Through a series of books and pamphlets he standardized appliances, inventing the systems now widely used, with modifications.

Angle's chapter, "The Angle system of regulation and retention of teeth," represented the first edition of what was later separately published as Angle's textbook on orthodontics with the same title. This chapter reappeared in the second edition of Haskell's manual (1890). The first separate edition of Angle's work was a revised and enlarged version of what originated as the chapter, issued in 1892. That separate edition was identified as the third edition.