Impact of gastric acidic challenge on surface topography and optical properties of monolithic zirconia.
OBJECTIVE
To evaluate the surface topography and optical properties of monolithic zirconia after immersion in simulated gastric acid.


METHODS
Four partially stabilized (PSZ) and one fully stabilized (FSZ) zirconia materials were selected for the study: Prettau (PRT, Zirkonzahn), Zenostar (ZEN, Ivoclar), Bruxzir (BRX, Glidewell), Katana (KAT, Noritake) and FSZ Prettau Anterior (PRTA, Zirkonzahn). IPS e.max (Ivoclar) was used as a control. The specimens (10×10×1.2mm, n=5 per material) were cut, sintered, polished and cleaned before immersed in 5ml of simulated gastric acid solution (Hydrochloric acid (HCl) 0.06M, 0.113% solution in deionized distal water, pH 1.2) for 96h in a 37°C incubator. Specimens were weighed and examined for morphological changes under scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Surface roughness was evaluated by a confocal microscope. Surface gloss and translucency parameter (TP) values were determined by a reflection spectrophotometer before and after acid immersion. The data was analyzed by one-way ANOVA followed by Tukey's HSD post hoc test (p<0.05).


RESULTS
PRTA displayed the most weight loss (1.40%) among the zirconia specimens. IPS e.max showed about three times more weight loss (3.05%) than zirconia specimens as an average. SEM examination indicated areas of degradation, bead-like shapes and smoothening of the polishing scratches after acid immersion. EDX displayed ion interactions and possible ion leaching from all specimens. Sa and Sq values for PRTA, ZEN and IPS e.max were significantly lower (p<0.05) after acid immersion. TP values increased significantly for PRT, ZEN and IPS e.max (p<0.05), while the surface gloss of ZEN, PRTA and IPS e.max increased (p<0.05).


CONCLUSIONS
Monolithic zirconia materials show some surface alterations in an acidic environment with minimum effect on their optical properties. Whether a smoother surface is in fact a sign of true corrosion resistance or is purely the result of an evenly progressive corrosive process is yet to be confirmed by further research.
Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Turku, Finland; Turku Clinical Biomaterials Centre (TCBC), University of Turku and City of Turku, Finland; Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, NC, USA. Electronic address: dr.taiseer@gmail.com.
Taiseer A
TA
Sulaiman
Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Turku, Finland; Turku Clinical Biomaterials Centre (TCBC), University of Turku and City of Turku, Finland.
Aous A
AA
Abdulmajeed
Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Turku, Finland; Turku Clinical Biomaterials Centre (TCBC), University of Turku and City of Turku, Finland.
Khalil
K
Shahramian
Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, 20500 Turku, Finland.
Leena
L
Hupa
Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, NC, USA.
Terrence E
TE
Donovan
Turku Clinical Biomaterials Centre (TCBC), University of Turku and City of Turku, Finland; Department of Biomaterials Science, Institute of Dentistry, University of Turku, and Division of Welfare, Turku, Finland.
Pekka
P
Vallittu
Department of Prosthetic Dentistry, Institute of Dentistry, University of Turku, Turku, Finland; Turku Clinical Biomaterials Centre (TCBC), University of Turku and City of Turku, Finland; Clinic of Oral Diseases, Turku University Central Hospital, Turku, Finland.
Timo O
TO
Närhi
D003343:Corrosion; D003764:Dental Materials / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry*; D008422:Materials Testing; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D055095:Optics and Photonics; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
D003764:Dental Materials; D015040:Zirconium; D006851:Hydrochloric Acid
Corrosion resistance; Monolithic zirconia; Optical properties; Simulated gastric acid; Surface topography