Comparison of Stainless Steel Archwire and Dental Arch Widths

Objectives: For orthodontic treatment using the preadjusted edgewise appliance, numerous preformed stainless steel archwires with different arch forms are commercially available from several manufacturers. As few studies have investigated the width of preformed stainless steel archwires, the present study compared the widths of preformed stainless steel archwires with dental arch widths.
Methods:
The dental arch widths and depths of mandibular dental casts of 30 normal subjects (15 females, 15 males; mean age, 23 years 2 months) were measured at the canine, first and second premolars, and first molar in consideration of the thickness of mandibular brackets and means and standard deviations were calculated. Twenty types of 0.016-in mandibular round preformed stainless steel archwires were selected from 6 major manufactures. The archwire widths were measured at the canine, first and second premolars, and first molar at the mean corresponding depths for the normal subjects using a flat-bed scanner (GT-X970, EPSON, Nagano, Japan) and image processing software (ImageJ, version 1.49, National Institutes of Health, Bethesda, MD). The means of archwire widths were compared with those of the dental arch widths at each tooth using Student’s t-test (P<0.05).
Results: The means and standard deviations of archwire widths from the canine to the first molar were 27.95±1.48 mm, 38.9±2.21 mm, 45.66±2.47 mm, and 51.21±2.85 mm, respectively. The corresponding values for the dental arch widths were 30.19±1.33 mm, 41.07±1.82 mm, 47.99±2.58 mm, and 55.73±2.66 mm, respectively. The means of archwire widths were significantly narrower than those of the dental arch widths at each tooth (P<0.05).
Conclusions: The mean widths of preformed stainless steel archwires were approximately 2mm from the canine to the second premolar, and 4.5mm at the first molar narrower than those of the dental arch widths. This result suggests that some customizing of the preformed stainless steel archwires especially at the first molar will be needed.