The success of an orthodontic treatment highly depends on appropriate archwire selection as well as a clinician's ability to predict response during treatment. Precise knowledge of the appliance properties is thus essential. When it comes to simulating the complex oral environment, in vitro methodologies cannot adequately model in vivo phenomena. Reusing archwires is common practise, although the detailed information of the influence of intraoral service on the materials still lacks. We are looking to fill this void by conducting in vivo retrieval analyses of phase transformation in superelastic orthodontic archwires during intraoral exposure using neutron spectroscopy. Retrieved and as-received nitinol archwires will be measured to determine the phase and texture change induced, relating this to mechanical property change, in order to inform practical treatment protocal adjustment.