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Alkaline-heat (AH) treatment is a feasible method to prepare Titanium (Ti) based metals with an active ceramic coating for biological applications. Currently, the AH treated Ti substrates are usually sterilized with ethylene oxide gas (EO) or Gamma-ray irradiation (GI) before biological experiments and clinical implantation. However, the EO process is complex and residual gas is toxic for tissue and cells whereas radioactive source is difficult to access for GI and therefore both methods are not practical for dental offices and laboratories. Previously, hydrothermal sterilization (HS) was proposed for all kinds of Ti based endosseous implants and had been proven promising for clinical applications due to its advantage of restoring the osseointegration of Ti implants stored for long-term. In this study, the effects of HS on properties of AH treated Ti were studied in comparison with conventional autoclaving (AC). Both sterilizations were carried out at 121 °C for 20 min in a common autoclave and distilled water was used as medium for HS only. Results showed that, both AC and HS altered the nano-structure of the ceramic coating formed by AH and caused significant Sodium (Na) loss. AC decreased crystallinity of the coating by forming numerous nano-sheets, whereas HS increased the crystallinity, densified the coating and improved its scratch resistance. AC depressed the formation of apatite, in contrast, a complete apatite layer was formed on the HS specimen after being immersed in simulated body fluid (SBF) for 4 days. Both attachment and proliferation of osteoblast-like MC3T3-E1 cells on the HS specimens were better than that on the AC ones. Decontamination, superhydrophilicity and high crystallinity from HS were believed to be the main contributors. In summary, the current results showed that HS can be used as a sterilization method for AH treated Ti implants in biomedical applications. [ABSTRACT FROM AUTHOR]

Titanium and its alloys have been widely used in the manufacture of endosseous implants due to excellent biocompatibility, low elastic modulus, and good chemical stability. However, the titanium based metals are essentially bioinert materials. In order to improve their bioactivity, biological coatings are usually applied. Recent studies found that, compared with hydroxyapatite coating, dicalcium phosphate anhydrous (DCPA, Monetite) coating maybe more bioactive due to higher solubility and release of Ca and P ions. In this work, DCPA coating was prepared through a novel and simple method. Briefly, high concentration DCPA solution was sprayed onto superhydrophilic titanium and the specimens were dried fast in an air-circulating oven. After repeating the process over 100 times, a compact coating was fabricated. The microstructure, chemical composition, wettability, and in vitro bioactivity of the coating were analyzed and evaluated. Results showed that the coating fully covered the substrate and consisted of a large number of uniformly sized DCPA granules that packed together closely. The coating showed good wettability and could keep the property for a long time. After immersion in simulated body fluid for 2 weeks, a large amount of bone-like apatite with low crystallinity was induced implying a good bioactivity. [ABSTRACT FROM AUTHOR]

Dental implants made of pure titanium suffer from abrasion and scratch during routine oral hygiene procedures. This results in an irreversible surface damage, facilitates bacteria adhesion and increases risk of peri-implantitis. To overcome these problems, titanium nitride (TiN) coating was introduced to increase surface hardness of pure titanium. However, the osteoconductivity of TiN is considered to be similar or superior to that of titanium and its alloys and therefore surface modification is necessary. In this study, TiN coating prepared through gas nitriding was partially oxidized by hydrothermal (HT) treatment and ozone (O 3 ) treatment in pure water to improve its osteoconductivity. The effects of HT treatment and O 3 treatment on surface properties of TiN were investigated and the osteoconductivity after undergoing treatment was assessed in vitro using osteoblast evaluation. The results showed that the critical temperature for HT treatment was 100 °C since higher temperatures would impair the hardness of TiN coating. By contrast, O 3 treatment was more effective in oxidizing TiN surfaces, improving its wettability while preserving its morphology and hardness. Osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression and mineralization were improved on oxidized specimens, especially on O 3 treated specimens, compared with untreated ones. These effects seemed to be consequences of partial oxidation, as well as improved hydrophilicity and surface decontamination. Finally, it was concluded that, partially oxidized TiN is a promising coating to be used for dental implant. [ABSTRACT FROM AUTHOR]

Dental implant made of pure titanium (Ti) is prone to scratch and abrasion during routine oral hygiene procedures. This results an increase in surface roughness and therefore, facilitates the adhesion of bacteria. In severe cases, this could lead to peri-implantitis. To overcome this problem, surface modification of Ti is necessary to improve its abrasion resistance. Besides, a strong implant–gingiva interface should also be guaranteed to prevent the adhesion of bacteria. In this study, titanium nitride (TiN) coating was first prepared with gas nitriding to increase surface hardness of pure the substrate. Then, the TiN was hydrothermally treated in CaCl 2 solution in order to improve its soft tissue biocompatibility. The effect of hydrothermal treatment temperature on surface properties of TiN was investigated and its biocompatibility was assessed in vitro using NIH3T3 fibroblast cell. It was determined that 120 °C was the critical temperature for the hydrothermal treatment condition. Treatment below 120 °C could incorporate Ca into TiN surface, oxidize TiN surface partially and then improve the wettability while preserving its morphology and hardness. Fibroblast cell attachment and proliferation were improved and cell spreading was enhanced on hydrothermally treated specimens compared with untreated ones. Improved wettability, Ca incorporation and negative surface due to interstitial N were believed to be the main reasons. Hydrothermal treatment is expected to make TiN a promising dental implant coating with excellent abrasion resistance and good soft tissue affinity. [ABSTRACT FROM AUTHOR]

• Hydrothermal sterilization can be used for final surface modification. • Ag was combined on to hydroxyapatite (HA) coating as silver phosphate, Ag 3 PO 4. • Sterilized Ag-contained HA coating showed excellent antibacterial property. Plasma sprayed hydroxyapatite (HA) coatings are widely used on bone implants due to excellent osteoconductivity. However, the coating also provides an appropriate environment for biofilm formation. To prevent bacteria adhesion, this study tried to modify the HA coating with silver (Ag) by hydrothermal sterilization in dilute silver nitrate (AgNO 3) solution at 121 °C for 20 min. Surface morphology, phase and chemical composition and antibacterial ability of the sterilized coating were investigated. After treatment, Ag was successfully incorporated onto the HA coating surface as in situ growing silver phosphate (Ag 3 PO 4) compound and the distribution of Ag element was homogeneously. Inhibition zone test showed that, the sterilized HA coating had an excellent antibacterial ability against Staphylococcus aureus (S. aureus). This simple and feasible method shows promising potential for clinical applications. [ABSTRACT FROM AUTHOR]

Surface oxidation is found to improve the osseointegration of titanium nitride (TiN) coatings on implantable titanium devices; nevertheless, systematic studies on effects of oxidation are still needed. In this study, multi-arc ion plated (MAIP) titanium nitride (TiN) coating was hydrothermally oxidized in pure water and then the structural, corrosion and wear properties of the coating were studied. A dense oxide layer of 20–50 nm in thickness is formed on TiN after hydrothermal oxidation above 200 °C. The layer is composed of flat anatase particles with a length of 50–150 nm and smaller anatase nanocrystallines located on their surface. The passivation behavior of TiN becomes much stronger in simulated saliva after oxidation treatment, showing a wider passivation range, a lower corrosion current and greatly improved impedance. In addition, the open circuit potential (OCP) of oxidized TiN remains much higher than that of untreated after 50 days of immersion. Sliding friction experiments against zirconia (ZrO 2) ceramic balls show that the wear type for the untreated TiN coating involves severe plowing and deformation. In contrast, only slight plowing is found on the surface of TiN covered with a compact anatase layer; the friction coefficient decreases sharply and the wear loss decreases obviously. [Display omitted] 1. Anatase nanolayer forms on TiN coating after hydrothermal oxidation in water. 2. Hydrothermal oxidation improves corrosion resistance of TiN in artificial saliva. 3. Anatase nanolayer contributes to obvious lubrication and wear reduction. [ABSTRACT FROM AUTHOR]