TY  - CONF
AU  - Rudolf, Rebeka
AU  - Fercec, Janko
AU  - Lazić, Vojkan
AU  - Veselinović, Valentina
AU  - Tomić, Sergej
PY  - 2017
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2201
AB  - The aim of this paper was to analyse the characteristic properties of different commercially available NiTi archwires (diameter 0.014 ''). Characteristic properties were determined by using DSC analysis for identification of phase temperatures and a tensile test for obtaining the mechanical properties, while semi-quantitative EDS analysis was used for their chemical composition. Analysis of phase temperatures showed that nickel- titanium orthodontic archwires, in the austenitic phase, were exhibiting superelastic effect in the oral environment (T=37 degrees C). The uniaxial stress-strain curves showed different values for the beginning and the end of loading due to the stress and transformation range. The investigation of the chemical composition showed an equiatomic NiTi alloy. The aim of the first phase of biocompatibility assessment of Ni-Ti archwires was to investigate the potential cytotoxicity on a model of rat thymocytes, where a direct contact exists between the archwire and the cells. The test was chosen because of the high sensitivity of thymocytes to proapoptotic stimuli and because the test includes the culture of non-adherent, non-proliferating cells, such as thymocytes, which is much more convenient for the evaluation of a material's cytotoxicity in direct contact, compared to the adherent cells such as fibroblasts. The experiment was designed to cultivate the Ni-Ti archwire samples with rat thymocytes, using different surface-over-volume ratios of the archwires in complete medium. The cytotoxic effect was evaluated by measuring the apoptosis. The aim of the second phase of the study was to investigate further the cytotoxic effects of Ni-Ti archwires in the short-term (24h) and long-term (48h) cultures of rat's thymocytes, which are highly sensitive to pro-apoptotic stimuli, where a direct contact exists between archwires and the cells.
PB  - Springer-Verlag Singapore Pte Ltd, Singapore
C3  - Proceedings of the International Conference on Medical & Biological Engineering 2017 (Cmbebih 2017
T1  - Characterisation of NiTi orthodontic archwires characteristic functional properties
VL  - 62
SP  - 323
EP  - 332
DO  - 10.1007/978-981-10-4166-2_49
ER  - 

@conference{
author = "Rudolf, Rebeka and Fercec, Janko and Lazić, Vojkan and Veselinović, Valentina and Tomić, Sergej",
year = "2017",
abstract = "The aim of this paper was to analyse the characteristic properties of different commercially available NiTi archwires (diameter 0.014 ''). Characteristic properties were determined by using DSC analysis for identification of phase temperatures and a tensile test for obtaining the mechanical properties, while semi-quantitative EDS analysis was used for their chemical composition. Analysis of phase temperatures showed that nickel- titanium orthodontic archwires, in the austenitic phase, were exhibiting superelastic effect in the oral environment (T=37 degrees C). The uniaxial stress-strain curves showed different values for the beginning and the end of loading due to the stress and transformation range. The investigation of the chemical composition showed an equiatomic NiTi alloy. The aim of the first phase of biocompatibility assessment of Ni-Ti archwires was to investigate the potential cytotoxicity on a model of rat thymocytes, where a direct contact exists between the archwire and the cells. The test was chosen because of the high sensitivity of thymocytes to proapoptotic stimuli and because the test includes the culture of non-adherent, non-proliferating cells, such as thymocytes, which is much more convenient for the evaluation of a material's cytotoxicity in direct contact, compared to the adherent cells such as fibroblasts. The experiment was designed to cultivate the Ni-Ti archwire samples with rat thymocytes, using different surface-over-volume ratios of the archwires in complete medium. The cytotoxic effect was evaluated by measuring the apoptosis. The aim of the second phase of the study was to investigate further the cytotoxic effects of Ni-Ti archwires in the short-term (24h) and long-term (48h) cultures of rat's thymocytes, which are highly sensitive to pro-apoptotic stimuli, where a direct contact exists between archwires and the cells.",
publisher = "Springer-Verlag Singapore Pte Ltd, Singapore",
journal = "Proceedings of the International Conference on Medical & Biological Engineering 2017 (Cmbebih 2017",
title = "Characterisation of NiTi orthodontic archwires characteristic functional properties",
volume = "62",
pages = "323-332",
doi = "10.1007/978-981-10-4166-2_49"
}

Rudolf, R., Fercec, J., Lazić, V., Veselinović, V.,& Tomić, S.. (2017). Characterisation of NiTi orthodontic archwires characteristic functional properties. in Proceedings of the International Conference on Medical & Biological Engineering 2017 (Cmbebih 2017
Springer-Verlag Singapore Pte Ltd, Singapore., 62, 323-332.
https://doi.org/10.1007/978-981-10-4166-2_49

Rudolf R, Fercec J, Lazić V, Veselinović V, Tomić S. Characterisation of NiTi orthodontic archwires characteristic functional properties. in Proceedings of the International Conference on Medical & Biological Engineering 2017 (Cmbebih 2017. 2017;62:323-332.
doi:10.1007/978-981-10-4166-2_49 .

Rudolf, Rebeka, Fercec, Janko, Lazić, Vojkan, Veselinović, Valentina, Tomić, Sergej, "Characterisation of NiTi orthodontic archwires characteristic functional properties" in Proceedings of the International Conference on Medical & Biological Engineering 2017 (Cmbebih 2017, 62 (2017):323-332,
https://doi.org/10.1007/978-981-10-4166-2_49 . .

TY  - JOUR
AU  - Čolić, Miodrag
AU  - Tomić, Sergej
AU  - Rudolf, Rebeka
AU  - Marković, Evgenija
AU  - Šćepan, Ivana
PY  - 2016
UR  - https://smile.stomf.bg.ac.rs/handle/123456789/2090
AB  - Superelastic (SE) and thermo-activated (TA) nickel-titanium (NiTi) archwires are used in everyday orthodontic practice, based on their acceptable biocompatibility and well-defined shape memory properties. However, the differences in their surface microstructure and cytotoxicity have not been clearly defined, and the standard cytotoxicity tests are too robust to detect small differences in the cytotoxicity of these alloys, all of which can lead to unexpected adverse reactions in some patients. Therefore, we tested the hypothesis that the differences in manufacture and microstructure of commercially available SE and TA archwires may influence their biocompatibility. The archwires were studied as-received and after conditioning for 24 h or 35 days in a cell culture medium under static conditions. All of the tested archwires, including their conditioned medium (CM), were non-cytotoxic for L929 cells, but Rematitan SE (both as received and conditioned) induced the apoptosis of rat thymocytes in a direct contact. In contrast, TruFlex SE and Equire TA increased the proliferation of thymocytes. The cytotoxic effect of Rematitan SE correlated with the higher release of Ni ions in CM, higher concentration of surface Ni and an increased oxygen layer thickness after the conditioning. In conclusion, the apoptosis assay on rat thymocytes, in contrast to the less sensitive standard assay on L929 cells, revealed that Rematitan SE was less cytocompatible compared to other archwires and the effect was most probably associated with a higher exposition of the cells to Ni on the surface of the archwire, due to the formation of unstable oxide layer.
PB  - Springer, Dordrecht
T2  - Journal of Materials Science-Materials in Medicine
T1  - Differences in cytocompatibility, dynamics of the oxide layers' formation, and nickel release between superelastic and thermo-activated nickel-titanium archwires
VL  - 27
IS  - 8
DO  - 10.1007/s10856-016-5742-1
ER  - 

@article{
author = "Čolić, Miodrag and Tomić, Sergej and Rudolf, Rebeka and Marković, Evgenija and Šćepan, Ivana",
year = "2016",
abstract = "Superelastic (SE) and thermo-activated (TA) nickel-titanium (NiTi) archwires are used in everyday orthodontic practice, based on their acceptable biocompatibility and well-defined shape memory properties. However, the differences in their surface microstructure and cytotoxicity have not been clearly defined, and the standard cytotoxicity tests are too robust to detect small differences in the cytotoxicity of these alloys, all of which can lead to unexpected adverse reactions in some patients. Therefore, we tested the hypothesis that the differences in manufacture and microstructure of commercially available SE and TA archwires may influence their biocompatibility. The archwires were studied as-received and after conditioning for 24 h or 35 days in a cell culture medium under static conditions. All of the tested archwires, including their conditioned medium (CM), were non-cytotoxic for L929 cells, but Rematitan SE (both as received and conditioned) induced the apoptosis of rat thymocytes in a direct contact. In contrast, TruFlex SE and Equire TA increased the proliferation of thymocytes. The cytotoxic effect of Rematitan SE correlated with the higher release of Ni ions in CM, higher concentration of surface Ni and an increased oxygen layer thickness after the conditioning. In conclusion, the apoptosis assay on rat thymocytes, in contrast to the less sensitive standard assay on L929 cells, revealed that Rematitan SE was less cytocompatible compared to other archwires and the effect was most probably associated with a higher exposition of the cells to Ni on the surface of the archwire, due to the formation of unstable oxide layer.",
publisher = "Springer, Dordrecht",
journal = "Journal of Materials Science-Materials in Medicine",
title = "Differences in cytocompatibility, dynamics of the oxide layers' formation, and nickel release between superelastic and thermo-activated nickel-titanium archwires",
volume = "27",
number = "8",
doi = "10.1007/s10856-016-5742-1"
}

Čolić, M., Tomić, S., Rudolf, R., Marković, E.,& Šćepan, I.. (2016). Differences in cytocompatibility, dynamics of the oxide layers' formation, and nickel release between superelastic and thermo-activated nickel-titanium archwires. in Journal of Materials Science-Materials in Medicine
Springer, Dordrecht., 27(8).
https://doi.org/10.1007/s10856-016-5742-1

Čolić M, Tomić S, Rudolf R, Marković E, Šćepan I. Differences in cytocompatibility, dynamics of the oxide layers' formation, and nickel release between superelastic and thermo-activated nickel-titanium archwires. in Journal of Materials Science-Materials in Medicine. 2016;27(8).
doi:10.1007/s10856-016-5742-1 .

Čolić, Miodrag, Tomić, Sergej, Rudolf, Rebeka, Marković, Evgenija, Šćepan, Ivana, "Differences in cytocompatibility, dynamics of the oxide layers' formation, and nickel release between superelastic and thermo-activated nickel-titanium archwires" in Journal of Materials Science-Materials in Medicine, 27, no. 8 (2016),
https://doi.org/10.1007/s10856-016-5742-1 . .