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Open AccessArticle

Changes in Roughness and Mechanical Properties of Invisalign® Appliances after One- and Two-Weeks Use

1
Department of Orthodontics, University of Sydney Dental School, Sydney, NSW 2010, Australia
2
Clinic of Orthodontics and Pediatric Dentistry, Center of Dental Medicine, University of Zurich, 8032 Zurich, Switzerland
3
Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, 11527 Athens, Greece
*
Author to whom correspondence should be addressed.
Materials 2019, 12(15), 2406; https://doi.org/10.3390/ma12152406
Received: 16 July 2019 / Revised: 23 July 2019 / Accepted: 26 July 2019 / Published: 28 July 2019
(This article belongs to the Special Issue Current and Future Trends in Dental Materials)
The aim of this study was to estimate the possible changes of surface roughness and the mechanical properties of Invisalign® appliances over one- and two-week of service. Forty appliances with attachments were retrieved after the end of orthodontic treatment from different patients. Half of them had been used for one week (1W), and the rest for two weeks (2W). Ten unused Invisalign® appliances were used as the control (CON). An equal number of teeth possessing attachments were cut of aligners deriving from all groups (1W, 2W, and CON), and the Sa, Sq, Sz, Sc, and Sv roughness parameters of the internal surface of the aligner attachment area and the opposite lingual side (which was in contact to enamel) were determined by optical profilometry. Then, ten first molars originating from all groups were embedded in acrylic resin, and were ground and polished. Instrumented indentation testing (IIT) was performed in order to determine the Martens hardness (HM), indentation modulus (EIT), and relaxation index (RIT), according to ISO 14577-2002. The produced data were statistically processed by one- or two-way analysis of variance (ANOVA) and multiple comparison post-hoc tests (a = 0.05). Both the surface roughness and mechanical properties of the retrieved groups (1W and 2W) showed statistically significant differences compared with CON, but without statistically significant differences between each other. The roughness variables of the as-received material were shown to be reduced after intraoral service demonstrating a wear effect. Ageing has a detrimental effect on the surface roughness and mechanical properties of Invisalign® appliances, although this effect is restricted to the first week of clinical usage. View Full-Text
Keywords: Invisalign®; orthodontic appliances; mechanical properties; relaxation; instrumented indentation testing Invisalign®; orthodontic appliances; mechanical properties; relaxation; instrumented indentation testing
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Papadopoulou, A.K.; Cantele, A.; Polychronis, G.; Zinelis, S.; Eliades, T. Changes in Roughness and Mechanical Properties of Invisalign® Appliances after One- and Two-Weeks Use. Materials 2019, 12, 2406.

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