Comparison of Preformed Orthodontic Archwires with Modified Dental Arch Forms: A Cross-Sectional Study

Background Selecting an archwire that respects a patient’s native arch form is central to stability and periodontal safety. Evidence from the last five years shows substantial heterogeneity in arch dimensions across populations, with contemporary preformed nickel–titanium (NiTi) archwires often wider than natural arches at the canine level. [1–6] This study quantified Yemeni adult arch dimensions and predominant arch forms and compared them with commonly used preformed NiTi archwires using a bracket‑point–based reference graph. Methods In this cross‑sectional analysis, pretreatment casts from 222 subjects (Class I and II; 16–28 years) were digitized. Clinical bracket points defined transverse widths (intercanine, Wc; intermolar, Wm) and depths (Dc, Dm). Arch form was categorized as tapered, ovoid, or square. Twenty‑seven rectangular 0.019×0.025‑inch NiTi archwires from 11 manufacturers were traced on a CBP reference grid that incorporated bracket‑base offsets. Archwire widths at the canine (L3) and first‑molar (L6) levels were compared with sample means. Repeatability was assessed on a subsample. [7–13] Results Ovoid was the predominant arch form followed by tapered and square. Males exhibited larger transverse dimensions than females. Across brands, most preformed NiTi archwires were wider than natural arches at the canine level. Mean (archwire – arch) differences were approximately + 3.4 mm at maxillary canines and + 1.9 mm at maxillary first molars; in the mandible, + 4.1 mm at canines and + 1.5 mm at first molars. Closest overall matches were 3M Ortho Form I (tapered), Dentaurum Arch Form I (tapered), and Ormco Ortho Small. [3, 5, 6, 14–18] Conclusions No single preformed archwire matched the Yemeni adult sample across arches and landmarks. Clinical selection should bias toward archwires ≈ 3–4 mm narrower at canines and ≈ 2 mm narrower at first molars to preserve patient‑specific arch forms, with individualized adjustments where needed. Reporting followed STROBE. [19, 20]