română MEDDOUR BELKACEM, BREK SAMIR, SAOUDI ABDELHAK, BAKHOUCHE HIBAT ERRAHMANE
Abstract
The choice of material for an implant is considered one of the best for successful arthroplasty. The prosthesis implants for knee joints are usually made of metallic biocompatible materials and polymers. However, this work proposes the replacement of stainless steel with zirconia. Zirconia is known for its weak cracking strength; therefore, this paper aims to predict the cracking of the femoral implant made of zirconia. To do so, a pre-crack was created while performing a numerical simulation to determine the stress intensity factor. This procedure is repeated for the incremented length of the pre-crack until the stress intensity factor reaches the fracture toughness value. To extend the investigation, three areas of the femoral implant where the stress concentration could be expected were considered. In all cases, the simulation results showed good zirconia behavior against cracking, and no crack propagation was expected.
Keywords
crack, toughness fracture; zirconia; knee
IOANA GOMOIU, MĂDĂLIN ENACHE, SIMONA NEAGU, ROBERT RUGINESCU, MARIA DUMBRĂVICIAN, ILEANA MOHANU, ROXANA COJOC
Abstract
Mural biocleaning is an ecological method performed with bacterial cells or enzymes and polysaccharides of microbial origin. This process allows the removal of black scales, organic materials used in the previous restoration, and accidental or accumulated organic deposits over time. Lipases produced by the halotolerant bacterium Bacillus sp. BA N P3.3 (E) were used to remove some restoration materials (Paraloid® B72 acrylic resin and Transparent Casein Dispersion) as well as accidental organic deposits (beeswax, sunflower oil, soot) from the surface of the murals. A new bacterial gel (HG) was obtained using a halotolerant bacterial strain. Bacterial lipases were integrated into the bacterial gel (HGE) and then applied to the surface of the frescoes mock-ups for 5 hours and 10 hours. The results obtained in the case of biocleaning with lipases integrated in the bacterial gel were more efficient than those with esterases integrated in Agarart. In a single application step, more than 50% of the existing restoration materials or organic deposits on the frescoes mock-ups were removed. Biocleaning efficiency was evaluated by direct examination and microscopy (optical and scanning electron microscope). The biocleaning of murals with bacterial metabolites is safe, low cost, non-invasive, risk free and very competitive with chemical cleaning methods.
Keywords
halotolerant bacteria, biotechnologies for restoration, bacterial lipases, integrated lipases in halohydrogels, biocleaning with bacterial metabolites.
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Year
2024
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Issue
54 (2)
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Pages
101-107
CICEK KORKMAZ TORUN, FURKAN ALP TORUN, ZEYNEP OKTE
Abstract
Fluoride and strontium have been reported to improve apatite crystals when combined and are associated with significant reductions in acid reactivity. This study aimed to investigate the effect of single and combined application of fluoride and strontium solutions on the remineralization of initial enamel lesions. The buccal surfaces of teeth were divided into 4 regions and NaF, SrCl2 and NaF+SrCl2 combinations were applied. Initial surface microhardness was measured. Then, the teeth were kept in demineralization solution for 96 hours and their surface microhardness was measured again. After the solutions were applied to the relevant areas of the teeth, they were subjected to a 21-day pH cycle. At the end of 21 days, surface microhardness measurements were made again The difference between the initial and post-demineralization surface microhardness is statistically significant. Differences between the initial surface hardness and the surface hardness values measured after applying the solutions were found to be statistically significant. There was no statistically significant difference in surface microhardness values between the surfaces on which NaF, SrCl2 and their combinations were applied. Surface recovery was found to be statistically significantly higher in the NaF applied group compared to the other groups. When the findings of the study were evaluated, it was seen that the application of SrCl2 could be effective in the remineralization of enamel.
Keywords
fluorid, strontium, microhardness, remineralization
ȘTEFAN-ALEXANDRU GAFTONIANU, CARMEN CHIFIRIUC, ECATERINA ANDRONESCU ADRIAN SURDU, ALEXANDRA-CRISTINA BURDUȘEL, ROXANA TRUȘCĂ
Abstract
The work in this paper focuses on the preparation, characterization, and functionalization of magnetite (Fe₃O₄) and cerium oxide (CeO₂) nanostructures. The present work was carried out to prepare the nanoparticles with a high degree of uniformity and stability through advanced techniques, and the functionalization of the nanoparticles was targeted at improving their colloidal stability and biocompatibility. Morphostructural analysis disclosed some characteristics that could explain their behavior when applied in biomedical fields. The antimicrobial activity was assessed against pathogens such as Staphylococcus aureus and Escherichia coli, while the antitumor activity was evaluated on HeLa cell lines. The results indicated a good antimicrobial effect and a certain level of selectivity in cytotoxicity against cancer cells, which means these nanostructures may have potential in specific therapy. This study offers important information regarding how the properties of the nanomaterials can be optimized for their most effective use in antimicrobial and oncological treatments.
Keywords
Nanoparticles, magnetite, cerium oxide, antimicrobial activity, antitumor effect, functionalized nanostructures.
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Year
2024
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Issue
54 (3)
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Pages
198-204