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

Richard Singer

Date of original Performance / Presentation

January 2022

Publication Date / Copyright Date

1-1-2022

Abstract

Objectives: To evaluate treatment outcomes in matched bicuspid extraction cases between treatment modalities using sliding mechanics and closing loop mechanics for space closure using a novel instrument for orthodontic treatment outcome assessment; the parameter of interest was a Treatment Outcome Score (TOS) across four Treatment Direction Indicators. Methods: In this retrospective matched-pair case study we used, pre- and post-treatment orthodontic records of 32 paired patients who exhibited Class I malocclusions and who were treated with four bicuspid extractions and when either sliding mechanics or closing loop mechanics were used. Patient records were randomly selected from NSU’s postgraduate orthodontic clinic. Cases were categorized and matched upon ‘Pre-treatment Difficulty Indicators’ (DIi0) using propensity score matching. In addition to age and sex, the following four indicators were used in the matching process: ANB, Frankfort Mandibular Plane Angle (FMA), Frankfort Mandibular Incisor Angle (FMIA) or Incisor Mandibular Plane Angle (IMPA) (for FMA  20), and lower lip to E-plane. Matched cases were assessed using a Treatment Outcome Score (TOS) across four Treatment Direction Indicators (TDIi), ordinal variables defined as the signed directional changes in the following four dependent variables from patient records: ANB, FMA, FMIA or IMPA (for FMA  20), and lower lip to E-plane; where, TDIi = sgn(DIi) = sgn(DIi0 – DIi1). Data was analyzed by means of univariate, bivariate, and multivariable Poisson Logistic regression (OR), or Multinomial Generalized Linear Modeling (PR differences) (controlling for age and sex) to provide descriptive statistics, crude associations of differences in each of the TDIi’s by treatment and to examine the multivariable associations between treatment modality and each TDIi , as well as, between treatment modality and Treatment Outcome Score (TOS= ∑_(i=1)^4▒〖TDI〗_i ), respectively. Results: No statistically significant differences were found when assessing the direction of change in each individual TDI or the sum of the direction of changes for the treatment variables. The difference in pre- and post-treatment difficulty indicator measurements describe a statistically significant greater reduction in ANB and LL-EP for the closing loop group. Additionally, we found increases in FMA and proclination of the mandibular incisors across both groups. Conclusions: 1) There were no significant associations between treatment modality and the direction of change in each individual treatment variable. 2) There were no significant associations between treatment modality and the sum of the direction of changes for the treatment variables. 3) There was a significant difference in the change between pre- and post-treatment ANB and LL-EP values for the closing loop group compared to the sliding group.

Disciplines

Dentistry

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