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KJO Korean Journal of Orthodontics

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pISSN 2234-7518
eISSN 2005-372X
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Korean J Orthod

Published online December 10, 2020

Copyright © The Korean Association of Orthodontists.

General trends in aligner thickness and gap width after thermoforming procedures of six commercial clear aligners with nano-CT evaluation: an in-vitro study.

Mario Palonea, Mattia Longob, Niki Arvedab, Michele Nacucchic, De Pascalis Fabioc, Giorgio Alfredo Spedicatod, Giuseppe Sicilianie, Luca Lombardof

a Reasearch Fellow, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
b Student, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
c Researcher, Division for Sustainable Materials, Research Centre of Brindisi, S.S. 7 Appia km 706,00, I-72100 Brindisi, Italy.
d Professor, School of Economics, Management and Statistics, University of Bologna
e Professor and Chairman, School of Dentistry, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
f Associate Professor and Chairman, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.

Correspondence to:Dr. Mario Palone, Research Fellow, Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy.
E-mail: mario.palone88@gmail.com
Telephone +39 3289523202

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objectives: To assess the effect of thermoforming on aligner thickness and gap width in six aligners systems with the same nominal thickness.
Materials and Methods: Six passive upper aligners were adapted to a single 3D-printed cast Each sample was subjected to high-resolution nano-CT. To investigate aligner thickness and gap width, a 2D analysis was conducted on a total of 204 measurements, assessing the effect of the following variables: tooth type (central incisor, canine and first molar), 2D reference point and aligner type. Data was analysed and compared using ANOVA and Tukey’s post-hoc testing (P<0.05).
Results: Tooth type, dental region and aligner type variables affect both the gap width and aligner thickness. Only in the F22, aligner thickness remains fairly stable across the arch.
Conclusions: All thermoformed samples displayed smaller aligner thickness and gap width at anterior teeth and both gingival and coronal centres than at posterior teeth and occlusal surfaces.

Keywords: Gap width, aligner thickness, thermoforming procedure, clear aligner therapy

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Korean J Orthod

Published online December 10, 2020

Copyright © The Korean Association of Orthodontists.

General trends in aligner thickness and gap width after thermoforming procedures of six commercial clear aligners with nano-CT evaluation: an in-vitro study.

Mario Palonea, Mattia Longob, Niki Arvedab, Michele Nacucchic, De Pascalis Fabioc, Giorgio Alfredo Spedicatod, Giuseppe Sicilianie, Luca Lombardof

a Reasearch Fellow, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
b Student, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
c Researcher, Division for Sustainable Materials, Research Centre of Brindisi, S.S. 7 Appia km 706,00, I-72100 Brindisi, Italy.
d Professor, School of Economics, Management and Statistics, University of Bologna
e Professor and Chairman, School of Dentistry, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.
f Associate Professor and Chairman, Postgraduate School of Orthodontics, University of Ferrara, Via Luigi Borsari 46, Ferrara 44121, Italy.

Correspondence to:Dr. Mario Palone, Research Fellow, Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy.
E-mail: mario.palone88@gmail.com
Telephone +39 3289523202

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objectives: To assess the effect of thermoforming on aligner thickness and gap width in six aligners systems with the same nominal thickness.
Materials and Methods: Six passive upper aligners were adapted to a single 3D-printed cast Each sample was subjected to high-resolution nano-CT. To investigate aligner thickness and gap width, a 2D analysis was conducted on a total of 204 measurements, assessing the effect of the following variables: tooth type (central incisor, canine and first molar), 2D reference point and aligner type. Data was analysed and compared using ANOVA and Tukey’s post-hoc testing (P<0.05).
Results: Tooth type, dental region and aligner type variables affect both the gap width and aligner thickness. Only in the F22, aligner thickness remains fairly stable across the arch.
Conclusions: All thermoformed samples displayed smaller aligner thickness and gap width at anterior teeth and both gingival and coronal centres than at posterior teeth and occlusal surfaces.

Keywords: Gap width, aligner thickness, thermoforming procedure, clear aligner therapy