Rinsing postprocessing procedure of a 3D-printed orthodontic appliance material: Impact of alternative post-rinsing solutions on the roughness, flexural strength and cytotoxicity

Anna-Lena Lambart; Alexander B Xepapadeas; Bernd Koos; Ping Li; Sebastian Spintzyk

doi:10.1016/j.dental.2022.06.010

Rinsing postprocessing procedure of a 3D-printed orthodontic appliance material: Impact of alternative post-rinsing solutions on the roughness, flexural strength and cytotoxicity

Dent Mater. 2022 Aug;38(8):1344-1353. doi: 10.1016/j.dental.2022.06.010. Epub 2022 Jun 22.

Authors

Anna-Lena Lambart¹, Alexander B Xepapadeas², Bernd Koos², Ping Li³, Sebastian Spintzyk⁴

Affiliations

¹ Department of Orthodontics, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany; Medical Materials Science and Technology, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany.
² Department of Orthodontics, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany.
³ Center of Oral Implantology, Stomatological Hospital, Southern Medical University, South Jiangnan Road No. 366, Guangzhou 510280, China; Medical Materials Science and Technology, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany. Electronic address: pingli_88@smu.edu.cn.
⁴ Medical Materials Science and Technology, University Hospital Tübingen, Osianderstrasse 2-8, Tübingen 72076, Germany; ADMiRE Lab - Additive Manufacturing, intelligent Robotics, Sensors and Engineering, School of Engineering and IT, Carinthia University of Applied Sciences, Europastraße 4, 9524 Villach, Austria.

PMID: 35752470
DOI: 10.1016/j.dental.2022.06.010

Abstract

Objective: The present study evaluated the effect of different rinsing postprocessing solutions on surface characteristics, flexural strength, and cytotoxicity of an additive manufactured polymer for orthodontic appliances. These solutions have been deemed an alternative to the standard isopropanol which is a flammable liquid, known to have toxic effects.

Methods: Tested specimens were manufactured using direct light processing of an orthodontic appliance polymer (FREEPRINT® splint 2.0, Detax) and post-processed with different post-rinsing solutions, including isopropanol (IPA), ethanol (EtOH), EASY 3D Cleaner (EYC), Yellow Magic7 (YM7), and RESINAWAY (RAY), respectively. All groups were post-cured following the manufacturer's instructions. Surface topography and roughness (Ra and Rv) were evaluated. In addition, flexural strength was measured by a three-point bending test. An extract test was performed to evaluate cytotoxicity. The data were analyzed by the Kruskal-Wallis test with Dunn's multiple comparisons test (p < 0.05).

Results: Various post-rinsing solutions did not significantly affect the roughness values (Ra and Rv). Specimens post-processed with EtOH (98.1 ± 12.4 MPa) and EYC (101.1 ± 6.3 MPa) exhibited significantly lower flexural strength compared to the groups of IPA (110.7 ± 5.3 MPa), RAY (112.1 ± 5.6 MPa) and YM7 (117.3 ± 5.9 MPa), respectively. Finally, there were no cytotoxic effects of parts cleaned with different post-rinsing solutions.

Significance: Considering the use of 3D-printed orthodontic appliance materials, different rinsing postprocessing procedures did not affect surface characteristics. However, the flexural strength was significantly influenced, which could be attributed to the chemical ingredients of the post-rinsing solutions. Various post-rinsing treatments had no alternation concerning cytocompatibility.

Keywords: Additive manufacturing; Cytotoxicity; Flexural strength; Polymers; Post-processing; Vat photopolymerization.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

2-Propanol
Dental Materials*
Flexural Strength*
Materials Testing
Orthodontic Appliances
Polymers
Printing, Three-Dimensional
Surface Properties

Substances

Dental Materials
Polymers
2-Propanol