Title Utjecaj korozivnog medija na strukturu i svojstva zubnih keramika Title (english) Corrosion media influence on the structure and properties of dental ceramics Author Sanja Štefančić Mentor Ketij Mehulić (mentor)Mentor Lidija Ćurković (komentor)Committee member Marko Jakovac (predsjednik povjerenstva)Committee member Jasenka Živko-Babić (član povjerenstva)Committee member Asja Čelebić (član povjerenstva)Committee member Zdravko Schauperl (član povjerenstva)Committee member Suzana Šegota (član povjerenstva)Granter University of Zagreb Defense date and country 2013-07-02, Croatia Scientific / art field, BIOMEDICINE AND HEALTHCARE Universal decimal classificationUDC ) 616.31 - Stomatology Abstract Zbog specifičnih svojstva cirkonij-oksidna (Y-TZP) zubna keramika ima široku primjenu u stomatologiji. Stoga je važno ispitati njenu kemijsku postojanost. Sva ispitivanja su provedena na tri skupine uzoraka Y-TZP zubne keramike BruxZir (Glidewell Laboratoriji 2012): čisti i polirani Y-TZP (uzorak C), polirani Y-TZP s dodatkom A3 boje(uzorak A3) i YTZP glazirani s dodatkom A3 boje (uzorak A3G). U svrhu karakterizacije određen im je kemijski sastav (PIXE analizom), fazni sastav (XRD analizom) i mikrostruktura (SEM analizom). Kemijska postojanost uzoraka praćena je: mjerenjem količine eluiranih iona (AAS i ICP MS metodom), mjerenjem parametara hrapavosti na mikro skali (profilometrom) i nano skali (AFM-om), mjerenjem tvrdoće po Vickersu (u rasponu od HV0,05 do HV3). Prema standardu ISO 6872 ispitivanje kemijske postojanosti zubne keramike provodi se u 4 %-tnoj vodenoj otopini octene kiseline pri 80 C tijekom 16 sati. U ovom radu produženo je vrijeme izloženosti uzoraka do 768 sati (32 dana) u svrhu određivanja brzine korozije. Najveća brzina korozije i promjena parametara hrapavosti na mikro skali određena je za uzorak A3G što se može pripisati kongruentnom otapanju glazure. Izmjerene promjene parametara hrapavosti (na nano skali) i daleko manje brzine korozije uzoraka C i A3 ukazuju na izuzetno dobru kemijsku postojanost cirkonij-oksidne (Y-TZP) zubne keramike u navedenim uvjetima. Vrijednosti tvrdoće (HV3) uzoraka C i A3 prije i poslije korozije nisu se značajno promijenile.XRD analizom je utvrđeno da tijekom procesa korozije dolazi do djelomične fazne transformacije ZrO2iz tetragonske u monoklinsku.
Abstract (english) Objectives: Among dental applications, the zirconia based ceramics are widespread becauseof their general properties. Therefore the aim of this study was to determine chemical stability of Y-TZP dental ceramics by modified standard method ISO 6872. Materials andmethods:Three different sample groups of Y-TZP material BruxZir (Glidewell Laboratories 2012.) wereused: sample (C) - pure polished zirconia, sample A3 - polished zirconia with addition of A3 dye and sample A3G - zirconia with A3 dyeand a glazed. Chemical compositon of Y-TZP was determined by PIXE method, phase composition was determined by XRD, microstructure was analysed by SEM. Chemical stability of investigated samples was monitoring by: measuring eluted ions (using AAS and ICP MS methods), measuring surface roughness parameters on microscale (using Perthometer) and nano scale (using AFM), determination Vickers hardness (in range from HV0.05 to HV3). According to the standard ISO 6872 chemical stability of dental ceramics is carried out in4 wt% CH3COOH aqueous solution at 80 C during16 h. In this work exposure time was extended up to 768 hours (32 days) inorder to determine the corrosion rate. Results: Maximum corrosion rate and changing of the roughness parameters on the microscale is determined for sample A3G which can be attributed to the congruent dissolution of glaze. The measured changes of the roughness parameters (at the nanoscale) and much less corrosion rate of samples C and A3 indicate extremely good chemical resistance zirconiumoxide (Y-TZP) dental ceramics ininvestigated conditions. Hardness values (HV3) for samples C and A3 before and after corrosion were not significantly changed. XRD analysis showed that the corrosion processcourse partial tetragonal to monoclinic phase transformation of ZrO2. The roughness parameters, for sample A3G, was significantly increased, showing higher penetration depthin all surface areas after immersion in corrosive media. All three sample groups showed the decreases of hardness by increasing of applied load. Conclusions: The measured changes of roughness parameters (at the nanoscale) and much less corrosion rate for samples C and A3 indicate their extremely good chemical resistance of zirconiumoxide (Y-TZP) dental ceramics in investigated conditions.
Keywords
Y-TZP
elucija iona
kemijska degradacija
hrapavost površine
tvrdoća po Vickersu
Language croatian URN:NBN urn:nbn:hr:127:435541 Study programme Title: dental medicine Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2017-02-14 11:38:12
