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Restorative Dentistry 2016
October 20-21, 2016
Volume 4, Issue 5 J Interdiscipl Med Dent Sci
ISSN: 2376-032X JIMDS, an open access journal
conferenceseries .com
October 20-21, 2016 Houston, USA
International Conference on
Restorative Dentistry and Prosthodontics
Rifat Gozneli et al., J Interdiscipl Med Dent Sci 2016, 4:5(Suppl)
Effects of PVD silica coating and multiple firing on low temperature degradation of aYTZ-Pceramic
monoclinic content and flexural strength changes
Rifat Gozneli, Tutku Cakır-Omur and Yasemin Ozkan
Marmara University, Turkey
Aim: Low temperature degradation or aging of zirconia is a negative phenomenon related to the transformation ability of the
tetragonal phase. The t-m phase transformation leads to micro and macro cracking of the zirconia. The purpose of the study
is to find out the effect of silica coating by Physical Vapor Deposition (PVD) system and multiple firing on Low Temperature
Degradation (LTD) and biaxial flexural strength of a Y-TZP ceramic after surface grinding and hydrothermal aging.
Materials & Methods: 90 disc shaped specimens (15 x1.2 mm) were equally divided into nine groups (n=10) according to the
test protocols. For each group, a different surface or heat treatments was applied: Aging (LTD), silica coating + LTD, grinding
+ LTD, grinding + silica coating + LTD, 3 times firing + LTD, grinding + 3 times firing + LTD, 5 times firing + LTD, grinding
+ 5 times firing + LTD and a control group. Accelerated aging was performed in steam autoclave (134° C, 2 bar) for 12 hours.
Following each treatment protocols, X-ray diffraction analysis was used to estimate the relative amount of monoclinic phase
and corresponding Transformed Zone Depth (TZD). Additionally, the biaxial flexure test was used to calculate the flexural
strength. Statistical analysis was conducted with Kruskal Wallis test and Turkey’s multiple comparison test.
Results: The tetragonal-to-monoclinic phase transformation of the Y-TZP ceramic was retarded by the application of PVD
silica coating only in the ground surfaces. The lowest monoclinic content was detected in grinding + 5 firing + LTD group. The
biaxial flexural strength (MPa) of grinding + LTD group was significantly higher than control and silica coating + LTD groups.
There was no significant difference between the other groups.
Conclusion: Multiple firing may be useful to decrease the relative monoclinic content after grinding procedures. PVD silica
coating did not change LTD resistance and biaxial flexure strength of zirconia. However, further studies about the treatment of
LTD should be made including the examinations on chipping problem in veneer ceramics.
Biography
Rifat Gozneli has completed his PhD in 2004 from Marmara University, Istanbul, Turkey and continued his Post-doctoral studies in Marmara University School of
Dentistry. He is now an Associate Professor and also working as a Tutor. He has published more than 20 papers in international and national journals. He has been
serving as a reviewer in national journals. He is the Member of Turkish Proshodontics and Implantology Association and Prosthodontics Academy and Gnathology
Association in Turkey.