Evidence map›Paper›PMID 38653792›Full record

ArticleJournal of orofacial orthopedics = Fortschritte der Kieferorthopadie : Organ/official journal Deutsche Gesellschaft fur Kieferorthopadie2025

Effect of thermomechanical aging on force system of orthodontic aligners made of different thermoformed materials : An in vitro study.

Tarek M Elshazly, Ludger Keilig, Diva Nang, Bijan Golkhani, Anna Weber, Hanaa Elattar, Sameh Talaat, Christoph Bourauel

Abstract read
In one paragraph

Article in Journal of orofacial orthopedics = Fortschritte der Kieferorthopadie : Organ/official journal Deutsche Gesellschaft fur Kieferorthopadie, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
7citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

7 citing papers in PubMed, 1 synthesis or guideline pooled it.

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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Tarek M ElshazlyOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany. tarek.m.elshazly@gmail.com.ORCID http://orcid.org/0000-0002-3219-9048
Ludger KeiligOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
Diva NangOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
Bijan GolkhaniOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
Anna WeberOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
Hanaa ElattarOrthodontic Department, Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia.
Sameh TalaatOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.
Christoph BourauelOral Technology Department, Dental School, University Hospital Bonn, Bonn, Germany.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeThe aim was to investigate the effect of aging by thermocycling and mechanical loading on forces and moments generated by orthodontic clear aligners made from different thermoplastic materials.

methodsA total of 25 thermoformed aligners made from 5 different materials, i.e., Essix ACE® and Essix® PLUS™ (Dentsply Sirona, Bensheim, Germany), Invisalign® (Align Technology, San Jose, CA, USA), Duran®+ (Iserlohn, Germany), Zendura™ (Fremont, CA, USA), underwent a 14-day aging protocol involving mechanical loading (a 0.2 mm vestibular malalignment of the upper left second premolar [tooth 25]) and thermocycling in deionized water (temperature range 5-55 °C). The 3D forces/moments exerted on tooth 25 of a resin model were measured at three time points: before aging (day 0), after 2 days and after 14 days of aging.

resultsBefore aging, extrusion-intrusion forces were 0.6-3.0 N, orovestibular forces were 1.7-2.3 N, and moments as mesiodistal rotation were 0.3-42.1 Nmm. In all directions, multilayer Invisalign® exhibited the lowest force/moment magnitudes. After aging, all materials showed a significant force/moment decay within the first 2 days, except Invisalign® for orovestibular and vertical translation. However, following thermomechanical aging, Duran®+ and Zendura™ aligners had equivalent or even higher vestibular forces (direction of mechanical load).

conclusionThermomechanical aging significantly reduced forces and moments during the first 48 h. Multilayer aligner materials exhibit lower initial forces and moments than single-layer ones, and were less influenced by aging. Material hardening was observed after subjecting some of the aligner materials to mechanical loading. Thus, orthodontists should be aware of possible deterioration of orthodontic aligners over time. This work also sheds light on how material selection impacts the mechanical behavior of aligners and may provide valuable guidance regarding optimal timing for the aligner changing protocol.

Indexed as

Dental Stress AnalysisOrthodontic Appliance DesignOrthodontic Appliances, RemovableTooth Movement TechniquesHumansIn Vitro TechniquesMaterials TestingStress, MechanicalBiomechanicsClear aligner appliancesOrthodontic forcesTooth movementTorque

Identifiers

PMID38653792
PMCPMC12373552

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.