The first comprehensive studies on root canal anatomy were published in the 1840s, with further contributions in the late 19th century using techniques like sectioning teeth and injecting materials into canals. In the early 20th century, improved methods like injecting celluloid or paraffin allowed for more detailed studies of variations. Landmark publications in the 1950s and 1960s further characterized the complex and variable nature of root canal anatomy using wax models and clearing techniques.