No reliable evidence to guide initial arch wire choice for fixed appliance therapy

Area of Science:

• Orthodontics
• Biomaterials Science

Background:

• Initial arch wires are crucial in the early stages of orthodontic treatment.
• Various materials, including stainless steel and nickel-titanium (NiTi), are used, each with purported benefits.

Purpose of the Study:

• To systematically review randomized controlled trials (RCTs) comparing the efficacy of different initial arch wire materials.
• To assess the impact of these materials on the speed of tooth alignment and patient-reported pain.

Main Methods:

• A comprehensive search of multiple databases (Cochrane Oral Health Group's Trials Register, CENTRAL, Medline, Embase) was conducted.
• Included were RCTs of initial arch wires in patients with fixed orthodontic appliances.
• Study selection, data extraction, and risk of bias assessment were performed independently by at least two reviewers.

Main Results:

• Nine RCTs involving 571 participants were included, all with a high risk of bias.
• No meta-analysis was possible due to heterogeneity in comparisons and outcomes.
• Insufficient evidence exists to determine differences in alignment rate or pain between stainless steel and NiTi wires, or between different types of NiTi wires.

Conclusions:

• There is a lack of reliable evidence supporting the superiority of any specific initial arch wire material for alignment speed or pain reduction.
• The effect of initial arch wire materials on root resorption remains uninvestigated.
• Well-designed, adequately-powered RCTs are necessary to establish the clinical significance of initial arch wire material performance.