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BACKGROUND: This in vitro study set out to find out how well oral cavity-dwelling bacteria can form biofilms and adhere on the surfaces of zirconium oxide samples created by 3D printing and milling technologies. METHODS: 5 strains of microorganisms were used for the study, and 40 zirconium oxide samples were prepared, which were divided into two groups (n = 20)-20 samples produced using removal technology comprised the control group, while 20 samples produced by 3D printing technology comprised the test group. The prepared samples were placed in culture media of bacteria and fungi that naturally occur in the oral cavity. Then, the intensity of biofilm build-up on the samples was determined using qualitative and quantitative methods. The results for both materials were compared with each other. RESULTS: No variations in the degree of biofilm deposition on zirconium oxide samples were found for the microorganisms Streptococcus mutans, Pseudomonas aeruginosa, Enterococcus faecalis, and Staphylococcus aureus. For Candida albicans fungi, more intense biofilm deposition was observed on samples made using 3D printing technology, but these differences were not statistically significant. CONCLUSION: The biofilm accumulation intensity of ceramics produced by additive technology is comparable to that of milled zirconium oxide, which supports the material's broader use in clinical practice from a microbiological perspective. This ceramic has demonstrated its ability to compete with zirconium oxide produced by milling techniques in in vitro experiments, but sadly, no in vivo tests have yet been found to determine how this material will function in a patient's oral cavity.
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Regarding the dynamic development of 3D printing technology, as well as its application in a growing part of industries, i.e., in the automotive industry, construction industry, medical industry, etc., there is a notable opportunity for its application in producing dental implants, which presents a promising alternative to traditional implant manufacturing methods. The medical industry is very restrictive regarding the applied materials, and it is necessary to use materials that exhibit very good mechanical and thermal parameters, show clinical indifference and biocompatibility, are non-allergenic and non-cancerous, and are likely to sterilize. Such materials are poly(aryl-ether-ketone)s (PAEK)s, mainly poly(ether-ether-ketone) (PEEK) and poly(ether-ketone-ketone) (PEKK), that are found to be high-performance polymers and can be defined as materials that retain their functionality even in extreme conditions. In the present paper, two types of PEEKs and PEKK were compared regarding their structural, mechanical, and thermal properties along with the biological activity toward selected strains. The tested samples were obtained with Fused Deposition Modeling (FDM) technology. The PEKK, after heat treatment, exhibits the most promising mechanical properties as well as less bacterial adhesion on its surface when compared to both PEEKs. Consequently, among the evaluated materials, PEKK after heat treatment stands out as the optimal selection for a dental prosthesis.
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BACKGROUND: The aim of this in vitro study was to determine the mechanical and functional properties of zirconium oxide ceramics made using 3D printing technology and ceramics produced using conventional dental milling machines. METHODS: Forty zirconia samples were prepared for this study: the control group consisted of 20 samples made using milling technology, and the test group consisted of 20 samples made using 3D printing technology. Their surface parameters were measured, and then their mechanical parameters were checked and compared. Density, hardness, flexural strength and compressive strength were tested by performing appropriate in vitro tests. After the strength tests, a comparative analysis of the geometric structure of the surfaces of both materials was performed again. Student's t-test was used to evaluate the results (p < 0.01). RESULTS: Both ceramics show comparable values of mechanical parameters, and the differences are not statistically significant. The geometric structure of the sample surfaces looks very similar. Only minor changes in the structure near the crack were observed in the AM group. CONCLUSION: Ceramics made using additive technology have similar mechanical and surface parameters to milled zirconium oxide, which is one of the arguments for the introduction of this material into clinical practice. This in vitro study has shown that this ceramic can compete with zirconium made using CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) methods.
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The paper presents the concept of a support system for the manufacture of machine spare parts. The operation of the system is based on a reverse engineering module enabling feature recognition based on a 3D parts scan. Then, a CAD geometrical model is generated, on the basis of which a machining strategy using the CAM system is developed. In parallel, based on the geometric model, a finite element model is built, which facilitates defining technological parameters, allowing one to minimize the risk of vibrations during machining. These parameters constitute input information to the CAM module. The operation of the described system is presented on the example of machining parts of the shaft class. The result is a replacement part, the accuracy of which was compared by means of the iterative closest point algorithm obtaining the RMSE at the level of scanner accuracy.
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The machinability of hard-to-cut CoCr alloys manufactured by Selective Laser Melting (SLM) technology is not yet sufficiently studied. Therefore, this work focuses on evaluation of surface texture formation during face turning of CoCr alloy. As part of the research, two specimen types were subject to comparison: made with the application of conventional casting and manufactured by additive manufacturing-SLM. A number of analytical and experimental methods were employed to describe the specimen composition and morphology, as: X-Ray Diffraction Analysis (XRD), optical metallurgical microscopy, confocal optical microscopy, and Vickers hardness HV0.1 measurements. In the next stage, the measurements of surface topographies formed during turning in a range of variable cutting speeds and feeds were carried out. Ultimately the multi-factor MANOVA (Multivariate Analysis of Variance) illustrating the influence of manufacturing technology, cutting speed, and feed ratio on selected surface parameters of samples was made. It has been demonstrated that during face turning with feeds up to 0.15 mm/rev, the similar values of surface roughness height and material ratio curve parameters were reached for both tested CoCr alloys. However, in a range of higher feed values, the surface quality of CoCr samples fabricated by SLM was lower than that reached for CoCr after casting process.
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Percutaneous nephrolithotomy (PNL) is an endoscopic technique used for treating large stones, multiple stones, and staghorn calculi. Although minimally invasive, complication rate of PNL reaches 25%, and it is partially associated with needle puncture during nephrostomy tract preparation. Continuous improvement of armamentarium and imaging methods and the introduction of three-dimensional (3D) visualizations optimize the procedure; however, the rapid and precise establishment of the nephrostomy tract is still difficult. In the present short communication, we present the PNL procedure assisted by a personalized 3D-printed surgical guide (SG) to ensure fast and precise needle access to the renal collecting system. We also describe the workflow for SG preparation, which consists of CT image acquisition and data segmentation, planning a safe needle insertion path, SG designing, and guide manufacturing. With the growing market of low-cost 3D printers, the presented technique can shorten the PNL procedure time and decrease the complication rate associated with needle puncture in a cost-efficient manner.