Wire Syndrome Associated with Multistrand Orthodontic Retainers: A Proposed Etiopathogenic Concept

Background/Objectives: Wire syndrome (WS) is a recognized post-orthodontic complication associated with bonded fixed retainers. It is characterized by abnormal, unexpected or excessive tooth movement in teeth that are still being held in place by a wire retainer. WS is likely to be underdiagnosed due to its slow, often asymptomatic, progression in the early stages, as well as due to a lack of knowledge among practitioners. This article proposes an etiopathogenic concept for WS associated with twisted or braided multistrand wires, with the aim of improving our understanding of the mechanisms involved in its onset and iatrogenic progression for the purposes of prevention and clinical management. Materials and Methods: A narrative review of the available clinical and experimental data in the literature was conducted to identify factors that could be involved in the initiation and progression of WS. Results: The qualitative analysis suggested that WS is the result of a multifactorial phenomenon that combines intrinsic factors linked to the mechanical properties of the orthodontic retainer and extrinsic factors corresponding to functional, muscular, and parafunctional stresses exerted on the teeth. Several etiopathogenic scenarios can be proposed, including loss of wire-composite adhesion, maintenance of this adhesion in the context of excessive muscular forces, and a mixed mechanism. In all cases, secondary deformation of the wire could alter its mechanical properties progressively, leading to unintended orthodontic activation of the appliance. This review also emphasizes the importance of rigorous retainer placement protocols, prolonged post-orthodontic follow-up and preventing excessive mechanical stress. Artificial intelligence could be a promising way to detect WS early on through the automated analysis of successive optical impressions. Conclusions: This review puts forward a coherent etiopathogenic concept for WS associated with multistrand wires. This concept is based on the interaction between wire deformation, progressive alteration to the wire-composite interface and mechanical stresses in the oral environment. This concept could explain the wide clinical variability of the syndrome, as well as its often slow and insidious progression. A better understanding of these mechanisms is essential for improving the prevention, early diagnosis, and clinical management of WS.