Effect of 3D printing system and post-curing atmosphere on micro- and nano-wear of additive-manufactured occlusal splint materials

Junichiro Wada; Kanae Wada; Sufyan Garoushi; Akikazu Shinya; Noriyuki Wakabayashi; Tsutomu Iwamoto; Pekka K Vallittu; Lippo Lassila

doi:10.1016/j.jmbbm.2023.105799

Effect of 3D printing system and post-curing atmosphere on micro- and nano-wear of additive-manufactured occlusal splint materials

J Mech Behav Biomed Mater. 2023 Jun:142:105799. doi: 10.1016/j.jmbbm.2023.105799. Epub 2023 Mar 24.

Authors

Junichiro Wada¹, Kanae Wada², Sufyan Garoushi³, Akikazu Shinya⁴, Noriyuki Wakabayashi⁵, Tsutomu Iwamoto⁶, Pekka K Vallittu⁷, Lippo Lassila³

Affiliations

¹ Department of Biomaterials Science, Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, Turku, 20520, Finland; Department of Advanced Prosthodontics, Tokyo Medical and Dental University - TMDU, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan. Electronic address: wadajun.rpro@tmd.ac.jp.
² Department of Biomaterials Science, Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, Turku, 20520, Finland; Department of Pediatric Dentistry / Special Needs Dentistry, Tokyo Medical and Dental University - TMDU, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
³ Department of Biomaterials Science, Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, Turku, 20520, Finland.
⁴ Department of Biomaterials Science, Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, Turku, 20520, Finland; Department of Dental Materials Sciences, School of Life Dentistry at Tokyo, The Nippon Dental University, Japan.
⁵ Department of Advanced Prosthodontics, Tokyo Medical and Dental University - TMDU, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
⁶ Department of Pediatric Dentistry / Special Needs Dentistry, Tokyo Medical and Dental University - TMDU, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
⁷ Department of Biomaterials Science, Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, Turku, 20520, Finland; Wellbeing Services County of South-West Finland, Lemminkäisenkatu 23, 20520, Turku, Finland.

PMID: 37028121
DOI: 10.1016/j.jmbbm.2023.105799

Abstract

Although additive manufacturing has been widely applied for occlusal splint (OS) fabrication, it is still unclear whether 3D printing system and post-curing atmosphere would play a role in the wear resistance of additive-manufactured OS. Therefore, the aim of this study was to evaluate the effect of 3D printing system (liquid crystal display (LCD) and digital light processing (DLP)) and post-curing atmosphere (air and nitrogen gas (N₂)) on the wear resistance of hard and soft OS materials for additive-manufactured OSs (KeySplint® Hard and Soft). The evaluated properties were microwear (by two-body wear test) and nano-wear resistances (by nanoindentation wear test) as well as flexural strength and flexural modulus (by three-point bending test), surface microhardness (by Vickers hardness test), and nanoscale elastic modulus (reduced elastic modulus) and nano surface hardness (by nanoindentation test). For the hard material, the surface microhardness, microwear resistance, reduced elastic modulus, nano surface hardness, and nano-wear resistance were significantly affected by the printing system (p < 0.05), while all the evaluated properties except flexural modulus were significantly affected by the post-curing atmosphere (p < 0.05). Meanwhile, both the printing system and post-curing atmosphere significantly affected all the evaluated properties (p < 0.05). The specimens additive-manufactured by DLP printer tended to show higher wear resistance in the hard material groups and lower wear resistance in the soft material groups when compared to those by LCD printer. The post-curing at N₂ atmosphere significantly enhanced the microwear resistance of hard material groups additive-manufactured by the DLP printer (p < 0.05) and soft material groups additive-manufactured by the LCD printer (p < 0.01), while it significantly enhanced the nano-wear resistance of both hard and soft material groups regardless of the printing system (p < 0.01). It can be concluded that 3D printing system and post-curing atmosphere affect the micro- and nano-wear resistance of tested additively manufactured OS materials. In addition, it can be also concluded that the optical printing system providing higher wear resistance depends on the material type, and using nitrogen gas as a protection gas during post-curing enhances the wear resistance of tested materials.

Keywords: Additive manufacturing; CAD/CAM; Nitrogen gas; Occlusal splint; Post-curing; Two-body wear.

Publication types

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

MeSH terms

Flexural Strength
Materials Testing
Nitrogen
Occlusal Splints*
Printing, Three-Dimensional*
Surface Properties

Substances

Nitrogen