Recently, Professor Xu Tianmin's team won the third prize in 2020 Chinese Medical Science and Technology Award with the program entitled "The Physiological Anchorage Spee-wire System (PASS)".

Molar forward displacement in extraction case is believed anchorage loss caused by reaction of retraction force on anterior teeth. However, studies on craniofacial growth show upper molars move forward even without orthodontic appliance. Professor Xu's team's studies on US metallic implant sample and Chinese growth sample show this kind of molar forward displacement can even reach 1/4 of a premolar extraction space during 12~14 years of age. They call this molar displacement physiologic anchorage loss and the form of it is upper molar forward tipping. Relative to upper molar, upper canine tips backward until fully eruption. The findings suggest that as long as we can prevent molar forward tipping and reduce canine backward displacement resistance, canine may move back automatically into extraction space without orthodontic force. Physiologic anchorage control technique is designed according to natural teeth growth pattern and therefore making anchorage control simpler and more effective.

Professor Xu's team has been committed to the study of physiological Anchorage control for many years, and has put forward a complete solution and correction system with China's independent intellectual property rights. In the hardware, the invention: XBT (crossed buccal tube) (Chinese invention patent), in the initial stage of orthodontic treatment can prevent the loss of physiological anchorage; MLF (multi-horizontal low friction brackets) (patented by Chinese and American inventions), can reduce the resistance of physiological tooth movement; tongue force mediator (patented by Chinese invention), use the physiological force of tongue muscle to control molars vertically. In terms of theoretical innovation, the dynamic growth and development of molars are organically integrated into the process of orthodontic treatment, and a four-dimensional orthodontic concept is put forward.