Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Department

College of Dental Medicine

First Advisor

Jeffrey Thompson

Date of original Performance / Presentation

January 2022

Publication Date / Copyright Date

1-1-2022

Abstract

Introduction: Different materials have been tested as orthodontic archwire to provide varying types of forces. Ranging from Titanium-Molybdenum alloy (TMA) to super elastic alloy (Nickel-Titanium), each material has unique properties that may be advantageous for a particular stage in orthodontic treatment or technique. Some clinicians have started to substitute Stainless Steel (SS) and Cobalt-Chromium alloy (Cr-Co) in a Multiloop Edgewise Archwire (MEAW) technique with a more recent material, Niobium-Titanium-Tantalum-Zirconium alloy (Gummetal, GM). This novel technique using GM is called Gummetal Edgewise Archwire (GEAW). Thus, the goal of this study is to investigate LDR of GEAW in comparison to TMA with a vertical loop, and conventional orthodontic wires used in the MEAW technique—SS and Cr-Co. The effect of increasing inter-backet distance and dimension of the loop on LDR is also evaluated. Methods: SS, Cr-Co, GM, and TMA wires were divided into 10 subgroups—5 maxillary regions (U2-3, U3-4, U4-5, U5-6, U6-7) and 5 mandibular regions (L2-3, L3-4, L4-5, L5-6, L6-7). Each subgroup had 5 specimens, with total of 200 specimens for this study. Each specimen was prepared by same examiner according to predetermined dimensions for each subgroup of specific wire type. Cr-Co specimens were heated to increase their stiffness. Each specimen was mounted on two brackets that were bonded to a metal fixture attached to the mechanical testing system (Instron Model 8841), and LDR was measured using a two-point bend test at a speed of 1.0 mm/min with maximum deflection of 1.0 mm. LDR was calculated by finding greatest slope within activation range using software (Bluehill 2 Version 2.26). Results: Kruskal-Wallis test showed that there were statistically significant differences among the medians of four groups: H(2) = 16.21, p = 0.001; H(2) = 11.31, p = 0.010; H(2) = 17.86, p < 0.001; H(2) = 11.72, p = 0.008; H(2) = 11.62, p = 0.009; H(2) = 17.58, p < 0.001; H(2) = 16.14, p = 0.001; H(2) = 17.86, p < 0.001; H(2) = 12.71, p = 0.005; H(2) = 16.21, p = 0.001 (in order of L2-3, L3-4, L4-5, L5-6, L6-7, U2-3, U3-4, U4-5, U5-6, U6-7). Pairwise comparisons using Dunn’s test indicated that LDR was significantly greater for Cr-Co than TMA and GM in L2-3 (p = 0.008, 0.003 respectively), TMA than SS in L3-4 (p = 0.012), GM than TMA in L4-5 (p = 0.030), GM and Cr-Co than SS in L4-5 (p < 0.001, p = 0.038 respectively), GM and Cr-Co than SS in L5-6 (p = 0.027, 0.012), Cr-Co than SS in L6-7 (p = 0.008), Cr-Co than GM and TMA in U2-3 (p < 0.001, p = 0.032 respectively), SS than GM in U2-3 (p = 0.035), GM and TMA than SS in U3-4 (p = 0.008, 0.003 respectively), GM than Cr-Co in U4-5 (p = 0.038), GM and TMA than SS in U4-5 (p < 0.001, p = 0.030 respectively), GM and Cr-Co than SS in U5-6 (p = 0.016, 0.008 respectively), GM than SS in U6-7 (p < 0.001). A Wilcoxon test was used for the analysis of changing inter-bracket span or loop dimension. For all four groups, LDR was significantly lower when inter-bracket span changed from 5.0 mm to 7.0 mm (p < 0.05), and when inter-bracket span changed from 7.0 mm to 9.0 mm (p < 0.05). For SS and Cr-Co, LDR was significantly lower when a horizontal loop changed from 4.5mm to 6.5mm (p < 0.05), and when a horizontal loop changed from 6.5mm to 7.5mm (p < 0.05). For TMA, LDR was significantly lower when vertical loop changed from 2.5mm to 3.5mm (p < 0.05). For GM, LDR was significantly lower for when vertical loop changed from 0.0 mm to 2.5 mm (p < 0.05). Conclusions: LDR measured under 10 different clinical settings for MEAW and GEAW were different among four groups: SS, Cr-Co, GM, and TMA. While GM had lower LDR in anterior regions (2-3) compared to SS and Cr-Co, GM had a higher LDR in posterior regions. GM and TMA displayed mostly similar levels of LDR which raises the question of whether TMA could also be used as a substitute for GM. Increasing inter-bracket distance or loop dimension within the same wire type decreased LDR for all four groups, which could be useful to control LDR. Whether GEAW can completely replace MEAW remains controversial, and further studies are needed.

Disciplines

Dentistry

Keywords

GEAW; Gummetal; Load deflection rate; MEAW; Multiloop edgewise archwire

Download

Download Full Text (936 KB)

Download
To access this thesis/dissertation you must have a valid nova.edu OR mynsu.nova.edu email address and create an account for NSUWorks.

Free My Thesis

If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the Free My Thesis button.

  Contact Author

Share

 
COinS