Purpose: of the study is to investigate the ultimate flexural strength and Young’s modulus of some materials, which can be used for complete denture fabrication by Masked stereolithography 3D printing technology. Design/methodology/approach: Three groups of five specimens each were fabricated. Two of the groups are 3D printed by Masked SLA 3D printer of two commonly used denture base resins. The third group is set to be a control as the specimens were fabricated of a heat-curing acrylic resin. A three-point flexural test tested the objects, and the data collected was used to determine ultimate flexural strength and Young’s modulus calculation. All the results are compared to the ISO Standard 20795-1. Findings: The data shows that the mean ultimate flexural strength of the 3D printed specimens is 87 MPa - 89 MPa. Their results are very similar to those for the heat-curing acrylic resin, which means the ultimate flexural strength is 93 MPa. The mean Young’s modulus obtained for the first group of 3D printed specimens is 2263.21 MPa and 2377.44 MPa for the second one. As for the control group, 2396.06 MPa is achieved. When ISO Standard 20795-1 is inspected, all the data obtained covers the minimum requirements. Research limitations/implications: The limitations of the study concern to some additional factors that should be observed for more detailed evaluation. For example, the level of the final polymerization of light-curing resins for 3D printing, their ability to washstand to different defect and denture-bearing area characteristics (the notch for the labial and buccal frenulum, chambers for torus release, etc.), the ability of the materials to withstand to cyclic load, etc. Practical implications: 3D printing is faster and cheaper than conventional methods for complete denture fabrication. The knowledge about the mechanical properties of the different materials for 3D printing is very valuable for properly selecting a material and approach for complete denture fabrication. Originality/value: Nowadays, 3D printing is essential in dentistry. For this reason, observation and knowledge of the raw materials properties is very important for the proper choice of a material and/or technology for each clinical case.
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The paper presents the results of the study of the titanium implant–elastomeric membrane attachment, conducted from the point of view of potential utilization of the results in forecasting the durability of retention elements representing a new solution of dentures based on implants. The examination was carried out using a device designed by the author, which allowed the simulation of the process of inserting and removing dentures. Titanium counter specimens, simulating implants, were subjected to surface modification through their sandblasting with 350 ěm and 500 ěm abrasives, so as to diversify their roughness. The elastomeric membranes constituting a retention element of the attachment were made of a silicone material, Molloplast B. The influence of the number of cycles (one cycle meaning one insertion and removal of a denture) on the attachment’s retention force was studied. In order to better reflect the natural conditions, the device was equipped with a chamber which made it possible to perform the examination in an artificial saliva environment. The study has shown that the application of the polymer material Molloplast B for constructing the new type retention elements of dentures based on implants ensures practically constant values of the attachment's retention force in the required 6-month utilization period. After the time of denture usage, being eight times longer than originally assumed, the loss of retention force does not exceed 43% in any of the attachments investigated and the retention force values still allow the attachments to operate, although their effectiveness is partly reduced.
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