Unit:
Speciality OrthodonticsΒιβλιοθήκη Οδοντιατρικής
Supervisors info:
Τσολάκης Απόστολος, Αναπληρωτής Καθηγητής, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Βασταρδή Ελένη, Αναπληρώτρια Καθηγήτρια, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Σηφακάκης Ιωσήφ, Αναπληρωτής Καθηγητής, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Original Title:
The mechanical properties of orthodontic aligners after different time periods of intraoral use.
Translated title:
The mechanical properties of orthodontic aligners after different time periods of intraoral use.
Summary:
Aim: The aim of this study is to evaluate the mechanical properties of the orthodontic aligners Clear Aligner®. It was also sought to examine the properties of the unprocessed raw material (PETG) used to manufacture these aligners and to compare them to those of the processed material.
Methods: 32 aligners used by 4 different patients were evaluated and studied at 0, 7, 10 and 14 days of use. Each aligner was divided in three segments (two posterior, one anterior) that resulted in 96 samples. Also 16 samples of unprocessed material (PETG) were studied. For all samples the elastic modulus, the ultimate tensile stress, and the yield stress were calculated by conducting tensile testing. Additionally, the material hardness was tested. The two-tailed Mann–Whitney test was performed to compare the measurements between the different samples. The level of significance was set at p-value 0.05.
Results: Analysis of the measurements indicated a statistically significant decrease of the elastic modulus between days 0 and 14 of use, of the ultimate tensile stress between days 0-7, and 7-10, and of the yield stress between days 0 and 7. Although any significant differences on hardness based on the day of use were observed, posterior segments demonstrated significantly higher values than anterior segments. All properties of the unprocessed material were statistically significantly higher than the processed samples.
Conclusions: The unprocessed material presented significant differences in every property tested in comparison to the processed aligners. It was found that the properties of the processed material may deteriorate over time during use. The present study provides evidence that thermoforming and ageing could potentially affect the mechanical properties of the aligners.
Main subject category:
Health Sciences
Keywords:
Orthodontic aligners, Aging, Mechanical properties
File:
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Siotou_Kalliopi_Master.pdf
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File access is restricted only to the intranet of UoA.
