Objective: To evaluate the antibacterial property of ultraviolet rays (UV)-treated titanium and its alloy by observing the attachment and colony-forming units (CFU) of Staphylococcus Aureus (Sa) and Fusobacterium Nucleatum (Fn).
Methods: Both of the titanium and its alloy were divided into 2 groups according to the UV treatment protocol as the UV-treated group (UV-Ti, UV-A), and two control groups (C-Ti, C-A) were also prepared. Then the sand-blasted and acid etched titanium and its alloy disks were stored in the dark and sealed containers for 4 weeks and treated with or without UV light for 48 hours. The hydrophilicity of disks were measured using contact angle measuring device. The attachment of the two kinds of bacteria were observed using inverted fluorescence microscope after stained by the Hoechst 33342 which was part of blue fluorescent dyes used to stain DNA and the results were replenished and verified by the Safranine O staining. CFU were used to measure the antibacterial property of the materials.
Results: The contact angles of UV-Ti (1.32 ± 0.29)° and UV-A (0.89 ± 0.07)° were smaller than those of C-Ti (81.18 ± 1.46)° and C-A (83.34 ± 0.06)° (P < 0.05). After being cultured on the surface of the two kinds of materials for 15 min, 30 min and 1 h, the attachment of Sa and Fn on the surface of titanium [(31 ± 13, 73 ± 13, 263 ± 49), (10 ± 7, 26 ± 19, 105 ± 37)] and its alloy disks [(64 ± 19, 57 ± 16, 304 ± 53), (11 ± 5, 59 ± 18, 124 ± 53)] which were treated with the UV light were much lower than those in control titanium groups[(139 ± 30, 271 ± 51, 749 ± 172), (164 ± 16, 227 ± 65, 483 ± 64)] and its control alloy group [(174 ± 11, 387 ± 39, 1409 ± 262), (265 ± 45, 374 ± 133, 910 ± 103)] (P < 0.05). What's more, the CFU number of the two kinds of bacteria decreased sharply after the UV treatment (P < 0.05).
Conclusions: UV treatment can reduce the attachment and viability of different kinds of bacteria and the antibacterial effect will at least last for 24 hours.