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

Cristina Godoy

Date of original Performance / Presentation

January 2026

Publication Date / Copyright Date

1-1-2026

Abstract

Introduction: The extraction of four premolars is commonly used in comprehensive orthodontic treatment to resolve malocclusions involving crowding or flared incisors. Because extraction therapy often takes longer due to the added difficulty of managing the extraction spaces, knowledge of factors that could prolong the overall treatment duration in postgraduate orthodontic clinics is vital to education and patient care. Objective: To examine the association between nine patient-, provider-, and appointment-related variables and the treatment duration of comprehensive orthodontic treatment with four-premolar extractions in a postgraduate orthodontic clinic, and to identify which of those variables have the greatest impact. Methods: A retrospective analysis was conducted on a sample of 90 patients who completed comprehensive orthodontic treatment with four-premolar extractions at the NSU postgraduate orthodontic clinic between 2010 and 2025. The dependent variable was treatment duration in months. Normality was assessed using the Shapiro-Wilk test. Bivariate associations were evaluated using Spearman correlations and Mann-Whitney U tests. Multiple linear regressions were conducted to show the independent impact of nine predictors including sex, age at start of treatment, total number of faculty, total number of resident providers, number of assigned faculty, percentage of assigned faculty coverage, number of emergency appointments, number of appointment intervals greater than six weeks, and presence of at least one impacted maxillary canine on the treatment duration. Results: The mean treatment duration was 40.3 months (SD = 14.8; median = 36 months; range, 18–92 months). Bivariate analysis revealed that the number of appointment intervals over six weeks long had the strongest association with treatment duration (ρ = 0.82, P < .001), followed by number of residents (ρ = 0.52, P < .001) and number of faculty (ρ = 0.39, P < .001). Sex (P = .55) and presence of impacted maxillary canines (P = .79) were not significantly associated with treatment duration in bivariate or multivariate analyses. The Enter multiple regression model explained 79.1% of the variance in treatment duration (adjusted R² = 0.791). Both this model and the secondary stepwise regression identified the same four statistically significant predictors: number of appointment intervals over six weeks (β = 0.75, P < .001), number of faculty (β = 0.26, P < .001), percentage of assigned faculty coverage (β = 0.15, P = .02), and number of residents (β = 0.13, P = .046). Conclusion: Overall, number of appointment intervals over six weeks long was the strongest predictor of treatment duration, with each additional extended interval associated with an increase of approximately 1.17 months of treatment. Provider-related variables, specifically the number of faculty and residents involved per case and the percentage of assigned faculty coverage, were also independent significant predictors, highlighting the critical role of continuity of care in determining treatment efficiency. These findings support targeted quality improvement efforts focused on reducing the number of lengthy appointment intervals and minimizing unnecessary provider transitions throughout treatment.

Disciplines

Dentistry

Keywords

academic setting; faculty coverage; orthodontic; postgraduate; premolar extraction; treatment duration

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