58 - Experimental Silver-Infiltrated Glass on Biofilm Formation in Monolithic Zirconia

Abstract

The aim of this study was to evaluate the effect of different coating applications of experimental glass with silver particles on surface properties, biofilm formation and inhibition of microbial adhesion to yttria-stabilized tetragonal zirconia (Y-TZP). 105 YZ T zirconia samples (VITA Zahnfabrik, Germany) with dimensions of 5.0 ×5.0 ×2.0 mm were divided into 7 groups: Polished YZ (P), Glazed YZ (G), YZ with infiltration glass (INF), YZ + 4% Ag (Ag4), YZ + 5% Ag (Ag5), YZ with glass + 4% silver (IAg4) and YZ with glass + 5% silver (IAg5). The experimental infiltration glass was made from silicic acid, which was obtained when sodium meta silicate (Na 2 SiO 3 5H 2 O) passed through aqueous solution (10% m / m) and an ion exchange resin (IR120 - Rohm and Haas). The glass with was obtained through a similar protocol, which was then followed by the addition of silver nitrate (AgNO 3 ) and silicon (SiO 2 ), aluminum (Al 2 O 3 ), calcium (CaO), sodium (Na 2 O), and potassium (K 2 O) oxides. The product upon completion comprised 5% AgNO 3 , 65% SiO 2 , 1.1% Al 2 O 3 , 0.59% K 2 O, 14.54% Na 2 O, 8.93% CaO and 3.41% MgO. Specimens were submitted to the following tests: surface roughness, colony-forming unit count (CFU) of Candida albicans, Streptococcus mutans and Streptococcus sanguinis, and Scanning Electron Microscopy (SEM). The different coating exhibited notable differences, both in relation to surface roughness, and bacterial and fungal adhesion. Regarding surface roughness, the Ag5 and IAg5 had a rougher profile when compared to the other groups, that were smoother and statistically similar to each other. However, in the CFU tests of Candida albicans and Streptococcus mutans groups P, G, and INF showed higher adherence of microorganisms, while all silver groups had less biofilm adherence, being statistically similar to each other. In the SEM it was possible to observe that all the groups of glass with silver (Ag4, IAg4, Ag5 and IAg5) presented silver particles anchored to the zirconia-glass system. The application of silver coating made the surface of the monolithic Vita HT zirconia resistant to the tested oral pathogens, causing inhibition of bacterial growth in the nearby surrounding region and also preventing the formation of biofilm on the ceramic surface.