Qianbing Wan

Fluoridated hydroxyapatite coatings on titanium obtained by electrochemical deposition.

Hydroxyapatite (HA) and fluoridated hydroxyapatite (FHA) coatings were deposited on titanium substrates using an electrochemical technique. Different concentrations of F(-) ions were incorporated into the apatite structure by adding NaF into the electrolyte. Typical apatite structures were obtained for all the coatings after electrodeposition and subsequent post-treatment, including alkaline immersion and vacuum calcination. The coatings were uniform and dense, with a thickness of approximately 5 microm. When the F-concentration was higher than 0.012 M in the electrolyte, a saturation of F in the coating occurred and the F/Ca ratio in the coatings became almost constant (F/Ca ratio=0.125). The FHA coatings showed higher bonding strength and lower dissolution rate than HA coating, particularly for those with a fluoridation level of 0.5-0.625. Compared with pure Ti, FHA and HA coatings exhibited higher biological affinity like cell proliferation and alkaline phosphatase activity. Regarding clinical application, it is suggested that a moderate content of F, such as Ca(5)(PO(4))(3)(OH)(0.375-0.5)F(0.5-0.625), be most suitable as a compromise among cell attachment, cell proliferation, apatite deposition and dissolution resistance.

The possible role of estrogen in the incidence of temporomandibular disorders

Epidemiologic literatures suggest that temporomandibular joint disorders (TMD) are more prevalent in women than in men. It is affecting approximately 7-15% of the adult population in North America, and 80% of patients treated for TMD are women. The severity of symptoms is also related to the age of the patients. The gender and age distribution of TMD suggests a possible link between its pathogenesis and estrogen. It has been reported that estrogen could influence the development, restitution and metabolism of the temporomandibular joint and associated structures such as bone, cartilage and articular disc. Estrogen can also influence the regulative mechanism of pain. In this article, we will use the hypothesis that the overwhelming majority of patients treated for temporomandibular disorders are women and use the available literature to examine the role of estrogens in TMD.

Osteogenic activity and antibacterial effect of zinc oxide/carboxylated graphene oxide nanocomposites: Preparation and in vitro evaluation.

The aim of this study was to prepare nanocomposites of carboxylated graphene oxide (GO-COOH) sheets decorated with zinc oxide (ZnO) nanoparticles (NPs) and investigate their advantages in the field of bone tissue engineering. First, ZnO/GO-COOH nanocomposites were synthesized by facile reactions, including the carboxylation of graphene oxide (GO) and the nucleation of ZnO on GO-COOH sheets. The synthesized ZnO/GO-COOH nanocomposites were then characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and transmission electron microscopy (TEM). The biocompatibility, osteogenic activity and antibacterial effect of ZnO/GO-COOH nanocomposites were further investigated. In the nanocomposites, ZnO nanoparticles with a size of approximately 12nm were uniformly decorated on GO-COOH sheets. Compared with GO-COOH and the control group, ZnO/GO-COOH nanocomposites significantly enhanced ALP activity, osteocalcin production and extracellular matrix mineralization as well as up-regulated osteogenic-related genes (ALP, OCN, and Runx2) in MG63 osteoblast-like cells. Moreover, ZnO/GO-COOH nanocomposites had an antibacterial effect against Streptococcus mutans. These results indicated that ZnO/GO-COOH nanocomposites exhibited both osteogenic activity and antibacterial effect and had great potential for designing new biomaterials in the field of bone tissue engineering.

A Self-Disinfecting Irreversible Hydrocolloid Impression Material Mixed with Chlorhexidine Solution

OBJECTIVE To examine the antibacterial effect and several physical properties of an irreversible hydrocolloid impression material mixed with chlorhexidine solution. MATERIALS AND METHODS The experimental irreversible hydrocolloid specimens were prepared and allocated into four groups (Group0.1 g/L, Group0.2 g/L, Group0.5 g/L, Group1.0 g/L) according to the concentrations of chlorhexidine solution used as the mixing liquid. Specimens mixed with distilled water served as a control. The antibacterial effect, three-dimensional accuracy, flowability, and setting time were tested. Statistical analysis was performed using a one-way analysis of variance and a Tukey test, which was used for multiple comparisons (alpha=.05). RESULTS Zones of growth inhibition were observed around the test specimens, but not around the control specimens, and there were significant intergroup differences in the diameters of the inhibition zones. In the accuracy test, no significant differences (P>.05) were detected among all the measurements for all groups, and the accuracy was clinically acceptable. Also, no significant differences in the flowability (P=.987) and setting time (P=.103) were detected. CONCLUSION Chlorhexidine self-disinfecting irreversible hydrocolloid impression material can exhibit varying degrees of antibacterial activity without influencing the three-dimensional accuracy, flowability, and setting time.

Osteogenic activity and antibacterial effect of porous titanium modified with metal‐organic framework films

As a new class of crystalline nanoporous materials, metal-organic frameworks (MOFs) have recently been used for biomedical applications due to their large surface area, high porosity, and theoretically infinite structures. To improve the biological performance of titanium, MOF films were applied to surface modification of titanium. Zn-based MOF films composed of zeolitic imidazolate framework-8 (ZIF-8) crystals with nanoscale and microscale sizes (nanoZIF-8 and microZIF-8) were prepared on porous titanium surfaces by hydrothermal and solvothermal methods, respectively. The ZIF-8 films were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The nanoZIF-8 film exhibited good biocompatibility, whereas the microZIF-8 film showed obvious cytotoxicity to MG63 cells. Compared to pure titanium and alkali- and heat-treated porous titanium, the nanoZIF-8 film not only enhanced alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and expression of osteogenic genes (ALP, Runx2) in MG63 cells but also inhibited the growth of Streptococcus mutans. These results indicate that MOF films or coatings may be promising candidates for bone tissue engineering.

EFFECTS OF ULTRASONIC RADIATION INTENSITY ON THE OXIDATION OF SINGLE-WALLED CARBON NANOTUBES IN A MIXTURE OF SULFURIC AND NITRIC ACIDS

One of the most commonly used techniques for purification and eventual dispersion of single-wall carbon nanotubes (SWNTs) is oxidation using strong acid and ultrasonication. Literature review reveals that ultrasonication of varying radiation intensities have been used during the acid oxidation, but few have reported whether ultrasonication of different intensities would have different effects on the structure and properties of SWNTs and how the effects are. An investigation of the effects of ultrasonic radiation intensity on SWNTs during oxidation in a mixture of sulfuric and nitric acids was conducted. Ultrasonication using different intensities (50 W, 100 W, 200 W and 300 W) was used. The acid-treated SWNTs were characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential test Boehm titration test and Raman spectrum analysis. Data from these experiments showed that high intensities provided stronger oxidizing conditions than lower ones. As ultrasonic intensity increased, larger number of SWNTs were destroyed and consumed to produce carbonaceous impurities, and more defects appeared in the tube walls.

Synergistic Enhancement of Antitumor Efficacy by PEGylated Multi-walled Carbon Nanotubes Modified with Cell-Penetrating Peptide TAT

In the present study, a cell-penetrating peptide, the transactivating transcriptional factor (TAT) domain from HIV, was linked to PEGylated multi-walled carbon nanotubes (MWCNTs) to develop a highly effective antitumor drug delivery system. FITC was conjugated on MWCNTs-polyethylene glycol (PEG) and MWCNTs-PEG-TAT to provide fluorescence signal for tracing the cellular uptake of the nanocarrier. After loaded with an anticancer agent, doxorubicin (DOX) via π − π stacking interaction, the physicochemical characteristics, release profile and biological evaluation of the obtained nano-sized drug carrier were investigated. The DOX loaded MWCNTs-PEG and MWCNTs-PEG-TAT drug carriers both displayed appropriate particle size, excellent stability, high drug loading, and pH-dependent drug release profile. Nevertheless, compared with DOX-MWCNTs-PEG, DOX-MWCNTs-PEG-TAT showed improved cell internalization, intracellular distribution and potentiated anticancer efficacy due to the TAT-mediated membrane translocation, endosomal escape and nuclear targeting. Furthermore, the therapeutic efficacy of DOX was not compromised after being conjugated with MWCNTs-PEG-TAT and the proposed nanocarrier was also confirmed to have a good biocompatibility. In conclusion, our results suggested that the unique combination of TAT and MWCNTs as a multifunctional drug delivery system might be a powerful tool for improved anticancer drug development.

A systematic review of the survival and complication rates of inlay-retained fixed dental prostheses

OBJECTIVES The aim of this systematic review was to investigate the survival and complication rates of inlay-retainer fixed dental prostheses (IRFDPs). DATA/SOURCES A systematic search was conducted in the PubMed, EMBASE, and Cochrane Library databases in English and time filters (articles published from 1960) were used. STUDY SELECTION Randomized controlled trails (RCTs), controlled clinical trials (CCTs) and prospective cohort studies on IRFDPs with a mean follow-up period of at least 2 years were included. Among 501 screened articles, one RCT and ten prospective cohort studies were included in this study. Of the included studies, information on failure and complications was independently extracted by two reviewers in duplicate. The failure and complication rates of IRFDPs were pooled with a random effect model and Poisson regression was applied to further investigate the influence of framework materials. The estimated 3- and 5-year survival rates of IRFDPs were 92.6% (95% CI: 85.8-97.6%) and 87.9% (95% CI: 77.4-96.1%), respectively. Debonding, fracture, dentine hypersensitivity and secondary caries were primary complications. The estimated 5-year rates of debonding, veneer fracture and secondary caries were 5.3%, 15.2% and 2.7%, respectively. Additionally, fiber-reinforced composite IRFDPs exhibited a lower incidence of debonding and caries with a higher rate of veneer fracture compared with metal-based and all-ceramic IRFDPs (p<0.05). CONCLUSIONS Compared with conventional fixed dental prostheses (FDPs) and implant-supported single crowns (ISCs), IRFDPs exhibited an acceptable 3-year survival rate but higher complication rates of debonding and veneer fracture. CLINICAL SIGNIFICANCE IRFDPs can be recommended as viable short- or middle-term minimally invasive alternatives to short-span conventional FDPs and ISCs, while the clinical outcome of IRFDPs as long-term definitive restorations still calls for further research. The indications of IRFDPs should be strictly controlled and monitored.

Speech effects of Hawley and vacuum-formed retainers by acoustic analysis: A single-center randomized controlled trial

OBJECTIVE To investigate the effects of alteration on speech articulation of adult patients between Hawley retainers and vacuum-formed retainers by an objective acoustic analysis of vowels and voiceless fricatives. MATERIALS AND METHODS Twenty adults, aged 19.0-29.0 years, who had just finished active orthodontic treatment were included in this study. They were divided into a Hawley retainer group and a vacuum-formed retainer group by sortation randomization method. The assessment of speech sounds was performed objectively using acoustic analysis before and after retainer application at the following time points: before wearing (T0), immediately after wearing (T1), and at 24 hours (T2), 1 week (T3), 1 month (T4), and 3 months (T5). RESULTS The production of /з:/, /i:/, /f/, /θ/, /s/, and /∫/ sounds for the Hawley retainer group and /i:/, /θ/, /s/, and /∫/ sounds for the vacuum-formed retainer group showed severe speech impairment according to acoustic analysis (P < .05). A comparison of the Hawley retainer group with the vacuum-formed retainer group revealed that the performance of /i:/, /f/, and /s/ sounds were significantly different (P < .05). CONCLUSION Although sound distortion could be found in both the Hawley retainer group and the vacuum-formed retainer group, changes in articulation were more obvious in the Hawley retainer group.

Comment on "amine-modified graphene: thrombo-protective safer alternative to graphene oxide for biomedical applications".

’ In a recent issue of ACS Nano, we read with great interest the excellent article by Singh et al. detailing the fabrication of amine-modified graphene (G-NH2) and their application potential in biomedicine. However, we found that the authors neglected a key point that the performances of both microand nanosized graphene in biological context were essential for guiding their biomedical applications. In this study, the authors constructed a suspended graphene-amine membrane consisting of singleor few-layer sheets. Flow cytometric analysis showed that identical size distribution of different graphene derivatives was fabricated, and high-resolution transmission electronmicroscopy (HR-TEM) revealed that the average dimension of different graphene derivatives was 2 μm. Finally, the authors concluded that G-NH2was a far safer alternative toGOandwas thuspotentially safe for biomedical applications in areas such as imaging, drug delivery, as well as photothermal therapy. However, all the graphene derivatives in this study were microsized, and nanosized graphene oxide, a widely studiedmaterial with high biocompatibility, was not mentioned as a control group in this article. As this study mentioned, graphene derivatives were finally developed to act as diagnostic or therapeutic materials. Such materials often required site-specific cellular entry to deliver their payload to subcellular locations hidden beneath cell membranes. Sahay thought that the uptake of those materials was regulated by their size. For example, Raffas study showed thatmicrosized carbon nanotubes with length longer than 2 μm could hardly enter cells, and Gratton showed that the nanosized particles seemed to enter cells more rapidly than the microparticles. Moreover, the pharmacokinetic profile analysis between the two types (microand nanosized) of GO suggested that a material with a small lateral dimension might bemore suitable for potential biomedical applications. Furthermore, microsized graphene derivatives might induce inflammation response, which might not be suitable for biomedical applications such as drug delivery and cancer therapy. Once inside the cells, themicrosized (2 μm)GOmight formwrinkles and then induce a much stronger inflammatory response with high release of key cytokines than nanosized (350 nm) GO. Yue concluded that the high cytokine level induced by 2 μm GO might be attributed to the strong steric effect of microsized GO. Besides, histological micrographics of mice showed that a large number of mononuclear cells infiltrated subcutaneous adipose tissue, and lipid-filled vacuoles as well as tissue impairment appeared after 2 μm GO injection. In contrast, the inflammation response was weak under the treatment of 350 nm GO. Such observations were in agreement with those by Schinwald, who reported that microsized graphene induced an inflammatory response and granuloma formation in lung and pleural space. Low inflammatory profiles exerted by nanosized GO can be beneficial for applications in drug carrier and cancer therapy, where improved biocompatibility is demanded. In conclusion, the size of graphene derivatives might be the control factor of biocompatibility of graphene derivatives. Therefore, when investigating the biocompatibility of graphene derivatives, both microsized and nanosized graphene derivatives should be considered. Finally, we would like to congratulate the authors for their contributions to graphene functionalization, which is innovative to biomedical research.