Abstract

Introduction: The fabrication of thermoformed orthodontic aligners involves processes that irreversibly alter material properties, resulting in aligners that exhibit high variation in thickness. The non-uniform thickness can lead to unpredictable forces that can adversely affect orthodontic tooth movement. With recent technological advancements enabling the printing of orthodontic aligners, it is of clinical interest to investigate their variation of thickness.

Purpose: This study utilized Micro-Computed Tomography (Micro-CT) and Geomagic Control X metrology software to compare the thickness of thermoformed and direct printed aligners.

Materials and Methods: Intraoral scans of 13 orthodontic patients were used to generate standard tessellation language (STL) files using a TRIOS intraoral scanner. One set of maxillary and mandibular thermoformed aligners using a 1.016 mm thick PET-G plastic, and one set of direct printed aligners, digitally designed to be 1.016 mm thick, were manufactured by Orchestrate 3D and Park Dental Research Group. The fabricated aligners were then scanned by a RayScan Micro-CT machine, and the resultant STL files were imported into Geomagic Control X software. The aligners were digitally superimposed, and the thicknesses was measured at 27 landmarks on the buccal, lingual, and occlusal surfaces of the central incisors, left canine, left first premolar, and left first molar. Wilcoxon paired sample T-tests were then used to compare the thicknesses of the thermoformed and direct printed aligners. All statistical analyses were conducted at α = 0.05.

Results: A total of 26 thermoformed and 26 direct printed aligners were included in the analysis. Compared to the intended 1.016 mm aligner thickness, the direct printed aligners exhibited a mean thickness of 1.10 mm, which was more accurate than the thermoformed aligners with a mean thickness of 0.540 mm (p-value < 0.001). The difference in thickness between the direct printed aligners and thermoformed aligners was statistically significant when analyzed by arch, site, and tooth (p < 0.001).

Conclusions: There is a statistically significant difference in the thickness of printed and thermoformed aligners. Printed aligners are the “gold standard” for aligners as they more closely match their designed thickness.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

School of Dentistry

First Advisor

V. Leroy Leggitt

Second Advisor

James Farrage

Third Advisor

Toufic Jeiroudi

Degree Name

Master of Science in Orthodontics and Dentofacial Orthopedics (MSODO)

Degree Level

M.S.

Year Degree Awarded

2023

Date (Title Page)

9-2023

Language

English

Library of Congress/MESH Subject Headings

Orthodontic Appliances, Removable; Printing, Three-Dimensional

Type

Thesis

Page Count

x, 57 p.

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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