Background: Wire syndrome (WS) is increasingly reported and associated with significant dento-periodontal consequences. However, no standardized diagnostic criteria or consensual classification exist, complicating early detection and potentially leading to confusion with orthodontic relapse, or periodontal pathology. This study aimed to develop for the first time a diagnostic approach for WS, define clinical diagnostic criteria, and propose a severity-based classification applicable in routine practice.

Materials and methods: A four-phase methodology was implemented using two retrospective case series (n=53). Phase 1 combined a literature review and expert clinical analysis to identify candidate diagnostic criteria and a preliminary severity grading. Phase 2 involved interdisciplinary expert consensus to refine decisive and non-decisive criteria. Phase 3 assessed inter-rater reliability using Gwet's AC1 coefficient on confirmed WS cases. Phase 4 evaluated discriminant validity in an independent cohort including both WS and non-WS cases.

Results: Three decisive criteria were retained, all required to confirm the diagnosis of WS (AC1=0.86): two dental criteria (differences in dental surface visibility or inclination/torque; misalignment of incisal edges or canine cusps) and one periodontal criterion (misalignment of gingival margins with or without gingival recession). Additional dental and periodontal non-decisive criteria were identified as optional complexity factors. Three severity grades were defined - early (grade 1), moderate (grade 2), and severe (grade 3) - based on gingival recession depth.

Conclusions: This Severity-Based Classification of Wire Syndrome provides a reliable and reproducible tool applicable across dental specialties and easily integrated into routine retention follow-up using three photographs, facilitating systematic early detection of WS.