Polymers for conventional, subtractive, and additive manufacturing of occlusal devices differ in hardness and flexural properties but not in wear resistance

• Published in: Dental materials 2021-03, Vol.37 (3), p.432-442
• Main Authors: Wesemann, Christian, Spies, Benedikt Christopher, Sterzenbach, Guido, Beuer, Florian, Kohal, Ralf, Wemken, Gregor, Krügel, Marei, Pieralli, Stefano
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Antagonists; CAD-CAM; Cyclic loads; Dental enamel; Dental restorative materials; Dentistry; Diamond pyramid hardness; Flexural Strength; Hardness; Humans; Indenters; Injection; Injection molding; Lithography; Manufacturing; Material properties; Materials Testing; Modulus of rupture in bending; Occlusal devices; Polymers; Premolars; Resins; Statistical analysis; Statistical methods; Stereolithography; Surface Properties; Thermal cycling; Variance analysis; Wear; Wear resistance
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2020.11.020

•Conventional, milled, and additive manufactured polymers showed comparable wear•Enamel antagonist wear was not influenced by the investigated materials•Additive manufactured polymers showed decreased mechanical properties To investigate the wear resistance of polymers for injection molding, subtractive and additive manufacturing of occlusal devices in comparison with enamel antagonist wear and material properties (i.e., hardness, flexural strength, and flexural modulus). Injection molding was compared with milling and the additive technologies stereolithography, low force stereolithography, and digital light processing. For each material, eight specimens were produced for wear measurements. Extracted human premolars served as indenters. All samples were subjected to two series of a 2-body wear test consisting of 200,000 circular loading cycles with an applied load of 1) 20 N and 2) 50 N in a thermocycling environment (5/55 °C, 30 s, 3860 cycles, H2O). Wear resistance was characterized by means of maximum depth and volume of the resulting traces. In addition, enamel wear of the indenters and Vickers hardness, flexural strength, and flexural modulus of the polymers were determined. Wear was statistically analyzed with linear general models for repeated measures and material properties with one-way ANOVA with post-hoc Tukey-HSD tests. Wear of the antagonists was not influenced by the material (P ≥ 0.343). Likewise, no differences in wear resistance were found between materials after cyclic loading with 20 N or 50 N (P ≥ 0.074). Material properties investigated revealed decreased values for the resins for the additive manufacturing with the exception of flexural strength of one material. Within the limitations of this in-vitro study, arylates for conventional, subtractive, and additive manufacturing of occlusal devices differ in material properties but not in wear resistance and antagonist wear.