Master of Science (M.S.) in Dentistry
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College of Dental Medicine
Publication Date / Copyright Date
Nova Southeastern University
Ezra Brown. 2018. Comparison of Preformed Archwires to Pretreatment Dental Casts Representing Normal Occlusions. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, College of Dental Medicine. (78)
Introduction: Preformed nickel-titanium archwires have become an almost universal standard for archwire selection in clinical practice. However, previous studies have found that that the intercanine and intermolar widths may be altered with the use of these wires. The patient’s original arch form should not be changed. To our knowledge, previous studies have not yet assessed the intercanine and intermolar widths of preformed archwires when categorized into ovoid, tapered, and square arch forms. Therefore, the purpose of this study was to evaluate the inter-arch dimensions of commercially available preformed nickel-titanium archwires relative to normal occlusion dental arches and when compared to archwires categorized into ovoid, tapered, and square arch forms. Methods: A total of 45 class I normal occlusion mandibular dental casts, 18 archwires, and tapered, square, and ovoid arch form templates were scanned. Casts were categorized into ovoid, tapered and square arch forms via best-fit method. Descriptive statistics of the intercanine and intermolar widths of all archwires and dental casts were assessed. We conducted linear-contrasts using robust-standard errors with a Bonferroni-Holm adjustment to measure the differences in inter-arch dimensions between pretreatment casts and preformed archwires by matching and differing arch forms. Concordance reliability and or intra-class correlation will be used to look for consistency between the measurements. Results: The intercanine and intermolar widths of preformed archwires (31.15 mm, SD 2.37 mm; M = 53.43, SD = 4.30 mm) were significantly larger than pretreatment casts (M = 26.11 mm, SD = 2.33 mm; M = 44.22 mm, SD = 2.98 mm) [SE = 0.65, p < 0.000, difference =5.06 mm: 95% 3.75, 6.36; SE = 0.95, P < 0.000, difference = 9.21 mm: 95% 7.31, 11.10]. The inter-arch dimensions among arch forms were very similar and all were significantly larger than pretreatment casts except for one condition: there was no statistically significant difference in the intercanine widths between square casts (M = 27.55 mm, SD = 1.37 mm) and tapered archwires (M = 30.18 mm, SD = 3.19 mm); SE = 0.95, p = 0.058 [difference = 2.63 mm: 95% CI: -0.06, 5.33). Conclusions: The average intercanine and intermolar widths of preformed archwires were significantly greater than pretreatment casts of normal occlusion archwires. It is recommended that orthodontists use archwires with narrower arch forms and inter-arch dimensions with the notion that archwires must always be individualized to the patient at some point.
Arch Form, Orthodontics, Preformed Archwires
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