Effect of different ratios of titanium dioxide nanotubes on the mechanical and antibacterial properties of the bulk fill composite

Aim: The purpose of this thesis is; evaluation of the effect of adding titanium dioxide nanotubes in different proportions on the mechanical and antibacterial properties of fluid bulk fill composite resin under in vitro laboratory conditions. Material and Method: Titanium dioxide nanotubes were synthesized by the hydrothermal method under laboratory conditions. Characterization of nanotubes; SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) and Raman Spectroscopy. In Estelite Bulk Fill Flow, a fluid bulk fill resin; TiO2 nanotube was added in different proportions (0.1%, 0.5%, 1%). Four different groups were formed by not adding TiO2 nanotubes to the control group. In order to evaluate the mechanical properties of fluid bulk fill composite; tests such as Vicker's microhardness, surface roughness, bending strength were applied. In the evaluation of bending strength, the fractured surfaces of the composite resin were examined with SEM. In addition, evaluation of the antibacterial effectiveness of nanotube addition against S.mutans and L.casei bacteria was performed by applying direct contact test. When evaluating the findings obtained in the study, IBM SPSS Statistics 22 (IBM SPSS, Turkey) program is used. In addition, Mann Whitney U Test, Shapiro Wilks, Kruskal Wallis test, Dunn's test, Friedman Test and Wilcoxon sign test and significance was evaluated according to p <0.05. Results: The results of the mechanical tests are evaluated; Addition of TiO2 nanotube does not change the roughness of the surface of composites both before and after polishing, adding 0.5% and 1% TiO2 nanotube to the composite resin both before and after polishing increases the microhardness of the composite, creating creation on the sub-surfaces of the composite (p> 0.05), It was observed that both the roughness and microhardness values increased in all groups with the polishing application on the resins (p <0.05), and the addition of titanium dioxide nanotube did not cause any change in bending strength (p> 0.05). If the antibacterial results were evaluated, the addition of titanium dioxide nanotube did not give the fluid bulk fill composite resin an antibacterial effect against S.mutans bacteria (p> 0.05). For L. casei bacteria; Antibacterial efficacy was observed in the group containing 0.5% TiO2 nanotube (p <0.05). Conclusion: The addition of titanium dioxide nanotubes provided an increase in the upper surface microhardness value without negatively affecting the mechanical properties of the fluid bulk fill composite resin. Antibacterial activity was obtained against L.casei bacteria of the fluid bulk fill composite resin. Keywords: nanotube, flowable bulk fill composite resin, antibacterial agent, S.mutans, L.casei, three point bending strength, microhardness, surface roughness.