Influence of metal coping fabrication technologies on mechanical properties of porcelain fused to metal crowns

Uvod: Dentalni porcelani in keramike se uporabljajo za izdelavo estetskih prevlek, mostičkov, lusk, inlejev, onlejev. Porcelan je po naravi zelo krhek material, zato ga v največ primerih nanašamo na kovinsko ogrodje. Takšne prevleke imenujemo kovinsko- porcelanske prevleke. V diplomskem delu je predstavljena izdelava kovinskih ogrodij na tri različne načine (ulivanje kovinskih ogrodij po klasični metodi, CAD/CAM-izdelava kovinskih ogrodij z metodo selektivnega laserskega taljenja in rezkanja). Pri kovinsko porcelanski vezi se močno razlikujejo trije parametri, to so adhezija, fizikalni parametri (retencija, koeficient termične ekspanzije), modul elastičnosti ter kemijski parametri (kovinski oksidi). Namen: Namen diplomskega dela je raziskati mehanske lastnosti preizkušancev ter opredeliti, kakšna je njihova strižna trdnost ter posledično, kolikšne so mehanske lastnosti vezi med kovinskim ogrodjem in porcelanskim plaščem. Metode dela: Literatura smo iskali v knjižnici Zdravstvene in Medicinske fakultete v Ljubljani, na podlagi predhodnega iskanja v sistemu COBISS. Članke smo iskali po zbirki podatkov PubMed, ScienceDirect ter z iskalnikom Google učenjak in vsebuje tako domača kot tuja strokovna dela. V eksperimentalnem delu diplomskega dela so bili izdelani preizkušanci. Praktični del temelji na analizi rezultatov, ki smo jih dobili z izdelavo preizkušancev. Rezultati: V rezultatih so predstavljeni kovinsko-porcelanski preizkušanci, ki smo jih izdelali po treh tehnologijah, in sicer smo stereolitografsko natisnjene preizkušance vložili v kiveto, jih ulili iz kovine, s tehnologijo CAD-CAM s pomočjo računalnika zmodelirali želene preizkušance ter jih poslali v rezkalni center, kjer smo jih zrezkali. Del preizkušancev smo 3D natisnili s tehnologijo selektivnega laserskega varjenja. Na preizkušance smo kasneje sintrali porcelansko maso in opravili mehanski preizkus trdnosti vezi med preizkušancem in porcelansko maso. Razprava in zaključek: Cilj strižnega preizkusa je bil ugotoviti strižne trdnosti vezi med z različno tehnologijo izdelanimi kovinskimi ogrodji in porcelansko maso. Tehnologije se med seboj močno razlikujejo, posledično pa se razlikuje tudi jakost vezi med kovinskim ogrodjem in porcelanskim plaščem. Jakost vezi prednjači pri rezkanih konstrukcijah, sledijo ulite, nato pa selektivno lasersko taljene konstrukcije.Introduction: Dental porcelain and ceramics are used for making esthetic crowns, dental bridges, veneers, inlays and onlays. Porcelain is very fragile by nature, therefore it is in the most cases fused on the metal frame. Such crowns are named porcelain fused to metal crowns. In this diploma work three different ways of metal crown production are presented (casting the metal frames by classical method, CAD/CAM production of metal frames with the method of selective laser melting and milling). The metal-porcelain bond/joint differs in three parameters, these are adhesion, physical parameters (retention), coefficient of thermical expansion), modul of elasticity and chemical parameters (metal oxides). Purpose: The purpose of this diploma work is to research the mechanical properties of porcelain fused to metal samples and to define their shear strenght and consequently what are the mechanical properties of bonds/joints between metal frame and porcelain coat. Working methods: We searched the literature in the library of the Faculty of Health Sciences and the Faculty of Medicine in Ljubljana on the basis of the previous searching in the COBISS system. The articles were sought by means of the data collection PubMed, ScienceDirect, and by the Google Scholar. It includes domestic and also foreign scientific literature. In the experimental part of this diploma work porcelain fused to metal samples were produced. Results: Here the samples are presented and they were made according to three different technologies: the stereolitography printed samples we put into casting ring and casted from metal, with CAD/CAM technology, which means that we made samples with the help of the computer and we sent them to milling centre where they were milled. Some samples were 3D printed with the selective laser melting technology. Later we sintered porcelain mass on samples and made the mechanical test of bond/joint strenght between the metal frame and porcelain mass. Discussion and conclussion: The aim of shear strenght test was to find out the bond/joint strenght between metal frames made by different technologies, and porcelain coat. Technologoies differ a lot among themselves, consequently also differs the intensity of bonds/joints between the metal frame and porcelain coat. The best bond/joint intensity is at the milled metal framework, then follows the casted metal framework and then selective laser melted framework