Paradigm Shift by Straight Wire Appliance and Its Impact on Anchorage Control

Abstract

Classical anchorage like in Tweed Edgewise and Begg technique all includes tip back bends on molars. With the development of straight wire appliance, especially the wide spread of NiTi wire that makes bending tip backs impractical if not impossible, orthodontists then gradually discard tip back bend and look for other anchorage methods. We then see a lot of TPA, Nance bar, headgear, and more and more TAD. Our recent study showed the conventional headgear can’t prevent upper molar from forward tipping on straight wire technique probably because it can’t resist 24 hours tip forward moment exerted by a straight wire on conventional molar tube when the dental arch was not straight before treatment. TAD is absolute anchorage; it won’t yield at all when pitting with other teeth. Then we see a lot of alveolar defects or root resorption of anterior teeth especially with the application of CBCT imaging technology. The emergence of TAD represents the end of the time of ever looking for stronger anchorage and meanwhile the advent of a new time of looking for more individualized and more physiologic anchorage.