Investigation of glazed Y-TZP dental ceramics corrosion by surface roughness measurement/Ispitivanje hrapavosti povrsine glazirane Y-TZP zubne keramike nakon izlaganja korozivnom mediju

Introduction: Among dental applications, the zirconia based ceramics are widespread because of their general properties. The changes in superficial surface roughness correspond to the structural changes in the material caused by the influence of corrosion. The aim of this study was to determine chemical stability of glazed Y-TZP using surface roughness measurements. Materials and methods: Five samples of Y-TZP material BruxZir (Glidewell Laboratories S 2012.) with the addition of pigment A3 were sintered, polished and glazed to imitate the finishing process in producing monolithic crowns. After determining the mass of the sample, each sample was immersed in 10 ml of 4 wt. % C[H.sub.3]COOH aqueous solution. The roughness was measured five times before and after immersion. Results: All measured roughness parameters have significantly increased, showing higher penetration depth in all surface areas after immersion in 4 wt. % C[H.sub.3] COOH aqueous solution compared to the initial values. Weight loss of investigated dental ceramics samples was 2.45 mg/[cm.sup.2] ± 0.026. Conclusion: Highly acidic conditions augment surface roughness of Y-TZP glazed dental ceramics. Key words Dental Porcelain; Surface Properties; Corrosion Uvod: Cirkonij-oksidna (Y-TZP) keramika zbog specificnih svojstava cesto se primjenjuje u stomatologiji. Gradivni materijal moze korodirati ako na njegovoj povrsini postoji razlika u koncentraciji elektrolita. Nekvalitetna obrada povrsine nadomjeska pridonosi korozivnim procesima koji i sami dodatno narusavaju povrsinsku morfologiju. Svrha ovog istrazivanja bila je ustanoviti kemijsku stabilnost glaziranog Y-TZP-a mjerenjem parametara hrapavosti povrsine. Materijali i metode: Pripremljeno je pet uzoraka keramike Y-TZP (BruxZir, Glidewell Laboratories S 2012) s dodatkom pigmenta A 3. Svi su bili sinterirani, polirani i glazirani--tako su simulirani zavrsni postupci u izradi monolitickih nadomjestaka. Nakon odrecivanja mase uzorka svaki je uronjen u 10 mL 4-postotne otopine octene kiseline. Svi parametri hrapavosti izmjereni su pet puta i to prije izlaganja korozivnom mediju i poslije toga postupka. Rezultati: Znacajan porast izmjerenih parametara hrapavosti, u odnosu na pocetne vrijednosti, upucuje na prodiranje 4-postotne vodene otopine octene kiseline. Zabiljezen je i gubitak tezine uzoraka i to u iznosu od 2,45 mg/[cm.sup.2] ± 0,026. Zakljucak: Vrlo kiseli uvjeti povecavaju povrsinsku hrapavost glazirane zubne keramike Y-TZP. Kljucne rijec