Comparative analysis of mechanical properties of orthodontic aligners produced by different contemporary 3D printers

• Published in: Orthodontics & craniofacial research Vol. 25; no. 3; pp. 336 - 341
• Main Authors: Zinelis, Spiros, Panayi, Nearchos, Polychronis, Georgios, Papageorgiou, Spyridon N., Eliades, Theodore
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.08.2022
• Subjects: 3-D printers; 3D printing; clear aligners; Comparative analysis; Incisors; instrumented indentation testing; Mechanical properties; Orthodontics; Statistical analysis; instrumented indentation testing; 3D printing; clear aligners; mechanical properties
• ISSN: 1601-6335; 1601-6343
• DOI: 10.1111/ocr.12537

Objective The aim of this study was to compare the mechanical properties of orthodontic aligners among different commercially available 3D printing devices. Materials and Methods Five 3D printers (Ka:rv LP 550, Swinwon; “KAR”), (L120, Dazz 3D; “L12”), (MiiCraft 125, Miicraft Jena; “MIC”), (Slash 2, Uniz; “SLS”) and (Pro 95, SprintRay; “PRO”) were used to prepare orthodontic aligners with dental resin (Tera Harz TC‐85DAW, Graphy). The central incisors of each aligner were cut, prepared and evaluated in terms of Martens‐Hardness (HM), indentation‐modulus (EIT) and elastic‐index (ηIT) as per ISO14577‐1:2002. Force‐indentation curves were recorded and differences among printers were checked with generalized linear regressions (alpha=5%). Results Statistically significant differences were seen for all mechanical properties (P < .05), which were in descending order: HM (N/mm2) as median (Interquartile Range [IQR]): SLS 108.5 (106.0‐112.0), L12 103.0 (102.0‐107.0), KAR 101.5 (97.5‐103.0), MIC 100.0 (97.5‐101.5) and PRO 94.0 (93.0‐96.0); EIT (MPa) as mean (Standard Deviation [SD]): SLS 2696.3 (124.7), L12 2627.8 (73.5), MIC 2566.2 (125.1), KAR 2565.0 (130.2) and PRO 2491.2 (53.3); and ηIT (%) as median (IQR): SLS 32.8 (32.3‐33.1), L12 31.6 (30.8‐32.3), KAR 31.3 (30.9‐31.9), MIC 30.5 (29.9‐31.2) and PRO 29.5 (29.1‐30.0). Additionally, significant differences existed between liquid crystal display (LCD) and digital light processing (DLP) printers for HM (P < .001), EIT (P = .002) and ηIT (P < .001), with aligners from the former having higher values than aligners from the latter printer. Conclusion Under the limitations of this study, it may be concluded that the mechanical properties of 3D‐printed orthodontic aligners are dependent on the 3D printer used, and thus, differences in their clinical efficacy are anticipated.