A Novel Bi-dimensional Archwire for Miniscrew-supported En-masse Retraction

This study was designed as a prospective single-arm pilot clinical trial to provide an initial clinical evaluation of a novel bi-dimensional archwire specifically developed for miniscrew-supported en-masse retraction of the maxillary anterior teeth. In adult orthodontic patients requiring extraction-based treatment, effective space closure depends not only on anchorage control, but also on the ability of the active retraction system to maintain acceptable control of the maxillary incisors during sliding mechanics. Conventional continuous rectangular stainless-steel archwires provide rigidity, but they may still be associated with frictional resistance, wire deformation, and incomplete torque control during retraction.

The archwire investigated in this study was newly developed as a single continuous stainless-steel assembly composed of a 0.019 × 0.025-inch anterior segment and 0.016 × 0.022-inch posterior segments joined by laser welding. The design was intended to combine greater anterior stiffness, to support better torque control of the maxillary incisors, with reduced posterior friction and binding during sliding mechanics. The intervention was applied under direct skeletal anchorage using self-drilling orthodontic miniscrews inserted bilaterally between the maxillary second premolars and first molars. Retraction was performed using nickel-titanium closed-coil springs delivering approximately 250 g of force per side.

Eligible participants were adult patients with skeletal Class II malocclusion and Class II Division 1 dental malocclusion who required extraction of the maxillary first premolars and en-masse retraction of the maxillary anterior teeth as part of their treatment plan. After leveling and alignment, the novel bi-dimensional archwire was inserted and the retraction phase was initiated. Participants were followed prospectively until completion of the en-masse retraction phase.

The primary outcome of the study was the monthly rate of maxillary anterior en-masse retraction assessed on three-dimensional digital dental models. The secondary outcome was the change in maxillary incisor torque measured on standardized lateral cephalometric radiographs using the bracket-archwire angle. This pilot trial was undertaken to determine whether this newly developed archwire could function as a clinically feasible biomechanical option and to generate preliminary outcome estimates for future randomized controlled trials.

Inclusion criteria

• Adults aged 18-28 years with skeletal Class II malocclusion (ANB angle 5°-7°)
• Class II Division 1 dental malocclusion according to Angle classification
• An average or vertical facial growth pattern
• A treatment plan requiring extraction of the maxillary first premolars
• A need for maxillary anterior en-masse retraction
• The presence of all permanent maxillary teeth except the third molars

Exclusion criteria

• Patients with previous orthodontic treatment,
• Craniofacial anomalies, systemic diseases affecting bone metabolism
• Active periodontal disease
• Poor oral hygiene
• Missing maxillary permanent teeth, or were using
• The use of medications known to influence bone metabolism