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Summary

Conflict of interest

Introduction
Achieving a stable, functional, and esthetic arch has long been the primary objective of orthodontic treatment. A key aspect in achieving these goals is the identification of a suitable arch form for each case. Preservation of the original arch form and size plays an important role in ensuring the long-term clozapine-n-oxide of orthodontic treatment results (Shapiro, 1974; Felton et al., 1987; DeLa Cruz et al., 1995). Felton et al. (1987) examined pretreatment, posttreatment, and postretention dental casts of 15 Class I and 15 Class II nonextraction orthodontically treated patients. When orthodontic treatment changed the arch form, the results frequently were unstable and relapsed to the pretreatment state. They concluded that in many cases, arch forms must be customized to obtain long-term stability (Felton et al., 1987). DeLa Cruz et al. (1995) examined the casts of 45 Class I and 42 Class II Division 1 malocclusion cases. Patients underwent extraction of the four first premolars and were followed for at least 10years after retention. The arch form rounded during treatment, followed by a change to a more tapered form during the postretention period. They concluded that the arch form tends to return to the pretreatment shape after retention.
Braun et al. (1999) superimposed 33 popular NiTi preformed archwire and bracket assemblies on maxillary and mandibular normal occlusion arch forms with the use of the Beta function. They found that the forms of the preformed wires did not emulate the natural human arch form. Specifically, all of the arch widths (measured at the canines and first molars) determined by the preformed wires were greater than the arch widths of the natural human arch form (Braun et al., 1999).

Materials and methods

Results
Coefficients and significance values for correlations between the MAEs were calculated for 10 randomly selected cases. Good reproducibility was observed (reliability: 0.91–0.98). All cases (combined, male, and female cases) displayed significant differences in MAE among the wires (P<0.001 by ANOVA, Table 1). Table 2 displays the brands and MAEs for the best-fitting wires in each group. In the upper arch, the best fit and least error were obtained with RMO Ovoid (0.0896cm) and Ormco Orthos Large (0.0899cm) for male cases, but with 3M Orthoform LA for female (0.0659cm) and combined cases (0.0855cm). In the lower arch, the best fit and least error were obtained with Ormco Orthos Large (0.0886cm) for male cases, 3M Orthoform LA (0.0695cm) and RMO Normal (0.0714cm) for female cases, and 3M Orthoform LA (0.0905cm), RMO Normal (0.0914cm), Ormco Orthos Large (0.0924cm), and Ormco Orthos Small (0.0947cm) for combined cases. When the results of both arches were matched as pairs, the best-fitting wires were clozapine-n-oxide Ormco Orthos Large for male cases and 3M Orthoform LA for female and combined cases.

Discussion
Correlation coefficients for MAEs between the original and redigitized data were 0.991 and 0.989 in the upper and lower arches, respectively (P<0.00 for both arches). The paired t test did not detect differences in the MAEs between the original and the redigitized data (P=0.360). Therefore, the method used can be considered sufficiently reliable. When a preformed archwire is used in orthodontic treatment, the form of the treated dental arch is altered to match the form of the wire. NiTi wires are highly elastic preformed archwires Cytological hybridization allow the introduction of larger cross-section wires and provide good efficiency during the early stage of orthodontic treatment (DeLa Cruz et al., 1995). Having archwires with forms that are harmonious with the normal dental arch form would be of great interest. Similar to studies by White (1978), Felton et al. (1987), Braun et al. (1999), and Camporesi et al. (2006), we compared preformed archwire forms to the dental arches of normal occlusion subjects. We studied 18 archwire designs from four popular orthodontic companies, including most designs and systems used in orthodontic practice and studied in prior investigations (Felton et al., 1987; Braun et al., 1999; White, 1978; Camporesi et al., 2006).