In vitro evaluation of oral streptococciadhesion with 2 different surface energy on grade 4 implant material modified with different surface stability of plasma polymerization technique

The aim of this in vitro study was to evaluate the applicability of the plasma polymerization technique with monomer containing thiol functional group on frequently used titanium implant biomaterial surfaces and the effect of the surface modification on microorganism adhesion.The study was performed using grade 4 commercial type (cp-Ti) pure titanium. A houndred and ten samples in 6 mm diameter and 2 mm height were prepared and each sample surfaces were metallographically polished with a diamond paste. 88 of these samples were modified with the plasma polymerization technique under different conditions. Control group was polished Ti surfaces consisted of 22 samples. In each group 2 samples selected randomly and immersed in artificial saliva. Before and after immersion samples surface analyzed with XPS, AFM, and contact angle measurements. Surface roughness and film thickness were determined by using atomic force microscopy. Contact angle measurements were performed with the sessile drop method using the OCA 20 contact angle system. Thereby, a video camera equipped with an image analyser visualizes the shape of the drop and the contact angle. The corresponding picture is saved in the computer and the contact angle is determined by software. 20 samples of each group divided 2 subgroups and incubated 72 hours with S. mutans and S. sanguis bacteria. Quantitative analysis of living bacteria adhered surfaces was performed using a colonyforming unit counting(CFU/ml).The study determined that plasma polymerized sample surfaces were smoother than the uncoated sample surfaces. Also, improvements in the hydrophilic character on modified titanium were determined by the contact angle measurements. The reduction of microorganism adhesion was significant on coated surfaces.In evaluation of adhesion of S. mutans and S. sanguis, contrary to expectations significant reduction of biofilm formation was seen on some of the samples. The unexpected reduction of bacterial adhesion was explained by covered reactivated Ti oxide surface, not related with surface energy. Also factors like covered Ti oxide surface and formation of stable, insoluble surfaces were reported more effective than surface energy.