Enhanced corrosion resistance of zinc-containing nanowires-modified titanium surface under exposure to oxidizing microenvironment.

Titanium (Ti) and its alloys as bio-implants have excellent biocompatibilities and osteogenic properties after modification of chemical composition and topography via various methods. The corrosion resistance of these modified materials is of great importance for changing oral system, while few researches have reported this point. Recently, oxidative corrosion induced by cellular metabolites has been well concerned. In this study, we explored the corrosion behaviors of four common materials (commercially pure Ti, cp-Ti; Sandblasting and acid etching-modified Ti, Ti-SLA; nanowires-modified Ti, Ti-NW; and zinc-containing nanowires-modified Ti, Ti-NW-Zn) with excellent biocompatibilities and osteogenic capacities under the macrophages induced-oxidizing microenvironment. The results showed that the materials immersed into a high oxidizing environment were more vulnerable to corrode. Meanwhile, different surfaces also showed various corrosion susceptibilities under oxidizing condition. Samples embed with zinc element exhibited more excellent corrosion resistance compared with other three surfaces exposure to excessive H2O2. Besides, we found that zinc-decorated Ti surfaces inhibited the adhesion and proliferation of macrophages on its surface and induced the M2 states of macrophages to better healing and tissue reconstruction. Most importantly, zinc-decorated Ti surfaces markedly increased the expressions of antioxidant enzyme relative genes in macrophages. It improved the oxidation microenvironment around the materials and further protected their properties. In summary, our results demonstrated that Ti-NW-Zn surfaces not only provided excellent corrosion resistance properties, but also inhibited the adhesion of macrophages. These aspects were necessary for maintaining osseointegration capacity and enhancing the corrosion resistance of Ti in numerous medical applications, particularly in dentistry.

Biocorrosion of pure and SLA titanium surfaces in the presence of Porphyromonas gingivalis and its effects on osteoblast behavior.

Objective: The study aims to investigate the biocorrosion behavior of Porphyromonas gingivalis on pure and SLA titanium surfaces and its effects on surface characteristics and osteoblast behavior. Methods: Pure and SLA titanium specimens were immersed in culture medium with P. gingivalis and incubated for 7 days. P. gingivalis colonization on the pure and SLA titanium surfaces was observed by scanning electron microscopy (SEM). The pure and SLA titanium surface characteristics were analyzed via X-ray photoelectron spectroscopy (XPS), surface roughness and surface wettability. The corrosion behaviors of pure and SLA titanium specimens were evaluated by electrochemical corrosion test. The osteoblast behavior of MC3T3-E1 cells on the pure and SLA titanium surfaces after P. gingivalis colonization was investigated by cell adhesion and western blot assays. Results: P. gingivalis colonized on the pure and SLA titanium surfaces was observed by SEM. The XPS analysis demonstrated reductions in the relative levels of titanium and oxygen and obvious reductions of dominant titanium dioxide (TiO2) on both titanium surfaces after immersing the metal in P. gingivalis culture. In addition, their roughness and wettability were changed. Correspondingly, the electrochemical corrosion test results revealed significant decreases in the corrosion resistance and increases in the corrosion rate of the pure and SLA titanium specimens after immersion in P. gingivalis culture. The results of the in vitro study showed that the pre-corroded pure and SLA titanium surfaces by P. gingivalis exhibited lower osteocompatibility and down-regulated the adhesion, spreading and osteogenic differentiation abilities of MC3T3-E1 cells. Conclusions: P. gingivalis was able to colonize on the pure and SLA titanium surfaces and weaken their surface properties, especially a decrease in the protective TiO2 film, which induced the biocorrosion and further negatively affected the osteoblast behavior.

[Incidence and mortality of oral and pharyngeal cancers in China, 2003 to 2007].

OBJECTIVE: To analyze the incidence and mortality of oral and pharyngeal cancers from 32 cancer registration centers, 2003 to 2007. METHODS: Data from 32 eligible cancer registries were included in this study. Both crude and age-standardized incidence and mortality of oral and pharyngeal cancers from 2003 to 2007 were calculated and stratified by area and gender. Age-stratified incidence and mortality, as well as the proportions of new and death cases of oral and pharyngeal cancer were also calculated at each site. RESULTS: Mouth, tongue and salivary gland were the most predilection sites of oral and pharyngeal cancers. The crude incidence for both oral and pharyngeal cancers was 3.15/10(5) from 2003 to 2007. The age-standardized incidence rates using the Chinese population (1982) and the World Segi's population were 1.75/10(5) and 2.26/10(5). The crude mortality of oral and pharyngeal cancer was 1.37/10(5) from 2003 to 2007; with age-standardized mortality rates, using the Chinese population (1982) and the World Segi's population were 0.69/10(5) and 0.94/10(5). Both incidence and mortality were higher in males than in females, higher in urban than in rural areas, and ascended with age. Age-standardized incidence and mortality in Zhongshan city ranked first among all the cancer registration areas. Age-standardized incidences by gender and area increased slightly from 2003 to 2007, while age-standardized mortalities were stable. CONCLUSION: Although the incidence and mortality of oral and pharyngeal cancer were low in China from 2003 to 2007, attention should also be paid since the exposure of relative risk factors did not seem to have reduced and the incidence increased slightly.