20.500.12556/DKUM-99528 Zobni implantati iz cirkonija: elektrokemijsko določanje korozijskih parametrov v umetni slini z dodatkom organskih kislin Zirconium dental implants: electrochemical determinantion of corrosion in artificial saliva supplemented with organic acids Dolgoročna učinkovitost kovinskih biomaterialov v ustnem okolju je močno odvisna od njihove interakcije s slino in njenimi spreminjajočimi se kemijskimi pogoji. V magistrskem delu smo analizirali korozijske lastnosti cirkonija med potopitvijo v umetni slini ob dodatku jabolčne, vinske in mlečne kisline. Korozijsko odpornost vzorcev smo ovrednotili z elektrokemijsko impedančno spektroskopijo (EIS) in potenciodinamsko polarizacijo, rezultate pa primerjali z gravimetrijskimi meritvami. Eksperimentalni del raziskave smo izvedli pri temperaturi 37 ˚C in atmosferskem tlaku 101,3 kPa, na ta način smo se čim bolje približali pogojem v ustni votlini. Pred začetkom elektrokemijskih meritev smo pripravili raztopino umetne sline s preračunanimi vrednostmi organskih kislin, ki jih lahko dnevno zaužijemo s hrano in pijačo. Prav tako smo skrbno pripravili površine vzorcev, da bi zagotovili primerljive eksperimentalne pogoje. Priprava vzorcev je obsegala brušenje, poliranje, razmaščevanje, ultrazvočno čiščenje in sušenje s komprimiranim zrakom. Pripravljene vzorce smo termostatirali v izbranih medijih 24, 48, 72 in 96 ur. Po posameznem času izpostavitve smo izvedli meritve EIS, nato pa še potenciodinamsko polarizacijo. Rezultate EIS smo prikazali z Nyquistovimi in Bodejevimi diagrami. Korozijsko odpornost cirkonija v posameznih preiskovanih medijih smo ocenili na podlagi vrednosti parametra R2, impedance in faznega kota. Rezultate smo dodatno ovrednotili s potenciodinamsko polarizacijo, pri kateri smo analizirali korozijski potencial (Ecorr), širino pasivnega območja in gostoto toka v pasivnem območju. Rezultati so pokazali, da cirkonij v vseh preiskovanih medijih ohranja korozijsko odpornost zaradi tvorbe zaščitne oksidne plasti. Prisotnost organskih kislin sicer vpliva na posamezne elektrokemijske parametre in s tem na stabilnost pasivne plasti. Meritve EIS so pokazale, da je imel cirkonij v raztopini umetne sline z dodatkom jabolčne kisline pri vseh časih izpostavitve najvišjo upornost pasivne plasti. Dodatek mlečne kisline je do 48 ur pasivacije povzročil najnižjo korozijsko odpornost, po tem času pa je pasivni film postal stabilnejši in odpornejši. Nasprotno se je odpornost pasivnega filma v umetni slini z dodatkom vinske kisline po 48 urah pasivacije postopoma zmanjševala. Rezultati elektrokemijskih meritev so se v veliki meri ujemali z rezultati gravimetrične metode. Na podlagi pridobljenih rezultatov lahko zaključimo, da izbrane organske kisline vplivajo na elektrokemijske lastnosti cirkonija, vendar ne preprečujejo nastanka zaščitne pasivne plasti na njegovi površini. Visoke vrednosti upora prenosa naboja, nizke gostote toka v pasivnem območju in prisotnost izrazitega pasivnega območja potrjujejo dobro korozijsko odpornost cirkonija v vseh preiskovanih medijih. Ti rezultati potrjujejo, da je cirkonij zaradi učinkovite pasivacije, kemijske stabilnosti in visoke odpornosti proti koroziji primeren material za uporabo v dentalni implantologiji. The long-term effectiveness of metallic biomaterials in the oral environment strongly depends on their interaction with saliva and its changing chemical conditions. In this master’s thesis, the corrosion properties of zirconium were investigated during immersion in artificial saliva containing malic, tartaric, and lactic acid. The corrosion resistance of the samples was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, and the results were compared with gravimetric measurements. The experimental part of the study was performed at a temperature of 37 °C and an atmospheric pressure of 101,3 kPa to simulate the conditions present in the oral cavity as closely as possible. Before the electrochemical measurements, an artificial saliva solution was prepared with concentrations of organic acids corresponding to typical daily dietary intake from food and beverages. The sample surfaces were also carefully prepared to ensure comparable experimental conditions. The preparation procedure included grinding, polishing, degreasing, ultrasonic cleaning, and drying with compressed air. The prepared samples were immersed in the selected media under thermostatic conditions for 24, 48, 72, and 96 hours. After each exposure period, EIS measurements were performed, followed by potentiodynamic polarization measurements. The EIS results were presented using Nyquist and Bode plots. The corrosion resistance of zirconium in the investigated media was evaluated based on the R₂ values, the size of the Nyquist semicircle, impedance, and phase angle. The results were further evaluated using potentiodynamic polarization, where the corrosion potential (Ecorr), the width of the passive region, and the current density in the passive region were analyzed. The results showed that zirconium maintained its corrosion resistance in all investigated media due to the formation of a protective oxide layer. However, the presence of organic acids affected individual electrochemical parameters and consequently influenced the stability of the passive layer. EIS measurements showed that zirconium in artificial saliva supplemented with malic acid exhibited the highest passive layer resistance across all exposure times. The addition of lactic acid caused the lowest corrosion resistance during the first 48 hours of passivation; however, after this period, the passive film became more stable and resistant. In contrast, the resistance of the passive film in artificial saliva with added tartaric acid gradually decreased after 48 hours of passivation. The results obtained from electrochemical measurements were largely consistent with the results of the gravimetric method. Based on the obtained results, it can be concluded that the selected organic acids affect the electrochemical properties of zirconium but do not prevent the formation of a protective passive layer on its surface. High charge transfer resistance values, low current densities in the passive region, and the presence of a distinct passive region confirm zirconium’s good corrosion resistance in all tested media. These results confirm that zirconium is a suitable material for use in dental implantology due to its effective passivation, chemical stability and high corrosion resistance. cirkonij dentalni implantati korozija umetna slina organske kisline elektrokemijske metode zirconium dental implants corrosion artificial saliva organic acids electrochemical methods true true false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-08-19 10:38:45 2026-09-11 14:48:26 2026-09-12 03:05:08 0000-00-00 00:00:00 2026 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 MAG_Kobe_Stozinic_Laura_2026.pdf MAG_Kobe_Stozinic_Laura_2026.pdf 1 B98A89E3BAB24F3B8369E9EB024F89AC c0529ee42164d53e0460e2b90e2198b399359a063f5bde28f555a2958c4a506e 3b08b007-acf8-11f1-b668-00155d0001be https://dk.um.si/Dokument.php?lang=slv&id=212060 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0