Archwire Materials in Lingual Orthodontics: Biomechanical Performance, Material Properties, and Potential Chemical Health Risks – A Review of Evidence and Clinical Recommendations

Abstract

Background:
Lingual orthodontics presents unique biomechanical challenges due to reduced inter-bracket distance, altered lever arms, and increased torque demands. In addition to biomechanical considerations, archwire materials used in lingual appliances may pose potential chemical and biological risks related to corrosion, ion release, and long-term oral exposure.

Aim:
To review available evidence on archwire sequencing in lingual orthodontics with emphasis on wire material properties, biomechanical performance, and potential chemical health risks associated with commonly used orthodontic alloys.

Methods:
A narrative literature review was conducted using PubMed and Google Scholar up to September 2025. Clinical studies, finite-element analyses, typodont studies, reviews, and material science investigations related to lingual orthodontic archwires were included. Data on wire composition, mechanical behaviour, corrosion resistance, ion release, and clinical sequencing protocols were extracted.

Results:
Nickel-titanium, copper-nickel-titanium, titanium-molybdenum alloy, and stainless-steel wires demonstrate distinct biomechanical and chemical behaviours in lingual systems. Reduced lever arms and higher torque demands often necessitate earlier use of rectangular wires. Evidence suggests that corrosion and metal ion release—particularly nickel—may be influenced by wire composition, surface finish, oral pH, and treatment duration, potentially impacting oral biocompatibility.

Conclusion:
A staged wire-sequencing protocol adapted to lingual biomechanics and material properties is recommended. While current evidence supports the effective clinical use of existing archwire alloys, further research is needed to assess long-term chemical exposure risks and to establish standardised, health-oriented wire-selection guidelines for lingual orthodontics.