Variation in form of mandibular, light, round, preformed NiTi archwires

Abstract

Objective: To evaluate the variation in form of nickel-titanium (NiTi) archwires by comparing them with the dental arch form of normal Japanese subjects before and after placing them in the first molar tubes. Materials and Methods: The mandibular dental casts of 30 normal subjects were scanned, and the dental arch depths and widths from the canine to the first molar were measured. Standardized images of 34 types of 0.016-inch preformed NiTi archwires were also taken in a 37uC environment, and the widths were measured and then classified by cluster analysis. Images of these archwires placed in a custom jig with brackets attached at the mean locations of the normal mandibular central incisors and first molar were additionally taken. The widths of the pooled and classified archwires were then compared with the normal dental arch widths before and after placement in the jig and among the groups (P , .05). Results: The archwires were classified into three groups: small, medium, and large. The archwire widths in the small and medium groups were narrower than those at all examined tooth widths, except in the case of the premolars of the medium group. After placement in the jig, the pooled archwire widths were found to be significantly narrower and wider at the canine and second premolar, respectively, than at the dental arch, but not in the individual comparisons between groups. Conclusion: The variation observed in the mandibular NiTi archwire forms significantly decreased following fitting into the normal positions of the first molars. (Angle Orthod. 2016;86:796-803.)

Can 3D imaging and digital software increase the ability to predict dental arch form after orthodontic treatment?

“…Preserving the dental arch form during orthodontic treatment is an important factor in the stability of the treatment outcome. 7 Unplanned contraction or expansion, especially at the intercanine and intermolar regions, can lead to instability. 8,14,15 Thus, correct selection of the primary archwire at the onset of treatment is highly important.…”

“…16 Also, racial differences that cause variations in dimensions and form of dental arch compared with the available archwires further highlight the significance of proper selection of a preformed archwire that best fits the dental arch. 7,17,18 Diagnostic software programs can provide accurate information and aid in determining more complex patterns of arch form. In addition, advances in computer analyses enable better definition of arch form individually for each patient.…”

“…6 In orthodontic treatment planning, the dental arch form of the patient should be initially determined and further preserved during treatment to achieve optimal esthetics, function, and stability. 7,8 Nouri et al 9 showed that the software environment enables a better fit of archwire with the dental arch and agreement of orthodontists is higher in the selection of archwires for regular occlusion patients.…”

Impact of the prefabricated forms of NiTi archwires on orthodontic forces delivered to the mandibular dental arch

“…Means and standard deviations (SDs) of the normal canine depth (4.84 mm ± 0.70 mm) and mean first molar depth (26.66 mm ± 1.57 mm) at the bracket slot (BS) points, which represented the position of the base of the bracket slot of the dental arch form of subjects with normal occlusions, were established based on our previous studies [ 14 , 21 ]. Means ± SDs as the normal ranges for ICWs (30.18 mm ± 1.32 mm) and IMWs (55.72 mm ± 2.66 mm) of the dental arch form were also established using data from the same previous studies [ 14 , 21 ].…”

Agreement of the clinician's choice of archwire selection on conventional and virtual models

“…Most orthodontists selected archwires subjectively by visual assessment of the adaptation of the archwires to the facial axis or facial surface of the teeth, incisal edges and cusp tips, or the facial portion of the proximal contacts. 5,[10][11][12] One study showed wide variation in the dimensions of working archwires fabricated on identical dental casts using subjective assessment among 30 clinicians. 13 McNamara et al 6 raised a question regarding the possibility of using digital models for accurate archwire selection.…”