MC3T3-E1 Cells on Titanium Surfaces with Nanometer Smoothness and Fibronectin Immobilization

The present study was aimed to evaluate the viability and total protein contents of osteoblast-like cells on the titanium surface with different surface mechanical treatment, namely, nanometer smoothing (Ra: approximately 2.0 nm) and sandblasting (Ra: approximately 1.0 μm), and biochemical treatment, namely, with or without fibronectin immobilization. Fibronectin could be easily immobilized by tresyl chloride-activation technique. MC3T3-E1 cells were seeded on the different titanium surfaces. Cell viability was determined by MTT assay. At 1 day of cell culture, there were no significant differences in cell viability among four different titanium surfaces. At 11 days, sandblasted titanium surface with fibronectin immobilization showed the significantly highest cell viability than other titanium surface. No significant differences existed for total protein contents among four different titanium surfaces at 11 days of cell culture. Scanning electron microscopy observation revealed that smoothness of titanium surface produced more spread cell morphologies, but that fibronectin immobilization did not cause any changes of the morphologies of attached cells. Fibronectin immobilization provided greater amount of the number of attached cells and better arrangement of attached cells. In conclusion, the combination of sandblasting and fibronectin immobilization enhanced the cell viability and fibronectin immobilization providing better arrangements of attached cells

Rapid analysis of metallic dental restorations using X-ray scanning analytical microscopy

Objectives: X-ray scanning analytical microscopy (XSAM) makes it possible to analyze small specimens in air without pretreatment. The purpose of this study was to utilize XSAM for the rapid analysis of metallic dental restorations by microsampling. Methods: Six different dental alloys were scratched with brand-new silicone points to obtain metal on the silicone point for compositional analysis. The fluorescent spectra of XSAM were measured to determine the metal attached to the specimen. Results: The major components of the six dental metals, except for palladium, were clearly detected. The identification of palladium was difficult since the fluorescent X-ray of palladium is quite close to that of rhodium, which is the source metal of the incident X-rays. However, with a slight modification of XSAM, palladium was also identified. The total time required for sampling and analysis with XSAM was less than 10 min. The amount of the attached metal was estimated to be less than 30 μg. This amount of sampling does not damage metal restorations. Significance: XSAM analysis using the microsampling technique is useful for the rapid analysis of metallic restorations

Quantitative analysis of biologic specimens by X-ray scanning analytic microscopy

X-ray scanning analytic microscopy (XSAM) can be used to visualize the elemental distribution in biologic specimens. In this article, the authors prepared standard specimens for XSAM and performed quantitative analysis of various elements dissolved in soft tissues. Two different types of standard specimens were prepared. Methylmethacrylate (MMA) resin-based standard specimens were prepared with organic compounds of elements for low-concentration standards and lithium borate glass-based standard specimens were prepared with oxides of elements for higher concentration standards. Using these standard specimens, the P and Ca concentrations in normal rat tissue and dissolved Ni, Fe, and Ni concentrations around metal-implanted tissues were quantitatively analyzed. The estimated concentrations of dissolved Fe, Cu, and Ni from the implants were 1000, 40, and 20 mM, respectively. From the concentration levels causing inflammation around these implants, the high toxicity for soft tissue of Ni and Cu at low concentrations, for example, 10 mM, was confirmed. The toxicity of Cu was estimated as next to that of Ni. In contrast, Fe had low toxicity despite high concentrations of dissolved Fe of as much as 1000 mM. In this article, it was possible to estimate the nonmetallic elements and low-concentration metallic elements dispersed in soft tissue by XSAM

Modification of the dentin surface by using carbon nanotubes.

Recent studies have shown that carbon nanotubes (CNTs) can be used as biomedical materials because of their unique properties. CNTs effect nucleation of hydroxyapatite, because of which considerable interest has been generated regarding the use of CNTs in dentistry. However, there are only a few reports on the use of CNTs as dental materials. In this study, we investigated the changes induced in the surfaces of tooth slices by the application of a coating of CNTs by observing CNT-coated tooth slices both macroscopically as well as under a scanning electron microscope. Further, we investigated the effect of CNT coating on the tensile bond strength of dentin adhesives. CNTs adhered easily to the tooth surfaces when tooth slices were suspended in a CNT-dispersed solution. Interestingly, it was observed that CNTs selectively adhered to the surfaces of dentin and cementum, possibly by adhering to their exposed collagen fibers. In addition, the CNT coating did not affect the tensile bond strength of dentin adhesives. These results indicate that coating of the teeth with CNTs can be a possible application of CNTs as dental materials

Toxicity evaluations of various carbon nanomaterials

After the discovery of fullerene and carbon nanotubes, various carbon nanomaterials were discovered or synthesized. The carbon nanomaterials have remarkable properties, different from bulk materials with the same chemical composition, and are therefore useful for industrial applications. However, the toxicity of nanomaterials may also differ from that of the bulk materials; this difference poses a concern. The physical similarity of nanomaterials to asbestos has led to evaluations for toxicity by many researchers using various methods. In this review, we compile and compare the toxicity evaluations of each carbon nanomaterial

Preparation and Properties of Dental Composite Resin Cured under Near Infrared Irradiation

A composite resin (CR) with photo-polymerization is widely used for dental filling material. Current CR has a restriction on the photo-polymerization depth because of the scattering of irradiated blue visible (VIS) light. Rare earth doped Y2O3 particles (Y2O3:RE) are known to emit blue VIS light under near infrared (NIR) excitation by an upconversion process. The particles can act as both filler to reinforce and illuminator to cure the resin by emitting blue VIS light under the irradiation of the NIR light, which propagates more deeply due to its longer wavelength. In this study, CR with Y2O3:RE was prepared. The Young's modulus of CR with Y2O3 was comparable with that of commercial CR, however, the hardness was lower than that of commercial CR. CR with Y2O3:RE was successfully cured with NIR irradiation. Then, the feasibility of Y2O3:RE as the NIR polymerization initiator using its upconversion emission for CR was suggested