The special section, “100 years of orthodontic history,” published in the December 2015 issue of the AJO-DO , delineates the important events in the past 100 years of orthodontics and provides a rich perspective to young orthodontists on how the field has developed. The timeline shows how far the practice of orthodontics has evolved; moreover, these major events could serve as building blocks to push the boundaries in the future.

Two clinician-scientists, Kaare Reitan and Per Rygh, who fundamentally contributed to the biology of tooth movement, are missing in the history timeline.

1951 Kaare Reitan

Histological analyses of periodontal tissue reaction in response to orthodontic tooth movement

1973 Per Rygh

Ultrastructure changes in periodontium as a function of orthodontic tooth movement

Reitan (1903-2000) and Rygh (1930-2008) extensively studied the histology of tooth movement in humans and rodents. Their findings partly defined the principles of tooth movement biology: the core of our daily orthodontic practice. In my opinion, we should add these 2 people to the list.

Editor’s note: Both Kaare Reitan and Per Rygh are included in another Centennial Special Section, “100 years of publishing, 100 people of influence,” in the May 2015 issue of the Journal (Am J Orthod Dentofacial Orthop 2015;147 (Suppl 2):S147-54).