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Pore size and connectivity of artificial bone scaffolds play key role in regulating cell ingrowth and vascularization during healing. The objective of this study was to develop a novel process for preparing 3D pore-interconnected open-cell bone substitutes with varying pore sizes. This was achieved by thermal-induced expansion, drying, then sintering the mixture of biphasic calcium phosphate (BCP) and a thermal responsive porogen comprising chitosan (CS) and hydroxypropyl methyl cellulose (HPMC). The interpolymer complexes (IPCs) of CS/HPMC were prepared and investigated by FT-IR. The mixtures of IPCs/BCP were heated up to 100 °C for analyzing their thermal expansion properties. This resulted in ~13% and ~42% volume increment for IPC-1/BCP and IPC-2/BCP, respectively, while ~230% volume increased in the case of IPC-3/BCP (therefore chosen for sintering bone blocks). Heating rate-dependent (0.20–0.25 °C/min range) sintering profiles for IPC-3/BCP were utilized to produce BCP bone blocks. Gasification of IPC during sintering resulted in the formation of interconnected porous structures, and the morphology was investigated by SEM, revealing varying sizes ranging from 106 ± 13 μm to 1123 ± 75 μm. The pore size range of bone blocks from 235 ± 46 μm to 459 ± 76 μm portrayed significantly high MC3T3-E1 cell viability with prominent filopodial extensions, and elongated cells, depicting efficient biocompatibility. Therefore, the process for preparing porous interconnected 3D bone blocks were feasible, thereby serving as an alternative for potential bone tissue engineering applications.

Background/purpose: Dysregulation of cell cycle checkpoint control may lead to the independence of growth regulating signals. Checkpoint protein such as the PD-1/PD-L1 immune checkpoint involving tumor cells and host immune defense lymphocytes is a well-studied therapeutic target in oncology. Acting at a cell surface receptor on plasma membrane integrin αvβ3, thyroxine stimulates intracellular accumulation of PD-L1 in cancer cells. Although resveratrol also binds to integrin αvβ3, it reduces PD-L1 expression. Materials and methods: In current studies, we investigated the roles of resveratrol and thyroxine in regulating expression of proliferation-related genes and checkpoint genes, PD-L1, BTLA in two oral cancer cell lines. Results: Thyroxine suppressed the expression of pro-apoptotic BAD but induced proliferative CCND1 expression in SSC-25 cells and OEC-M1 cells. It activated expression of PD-L1 and BTLA in both cell lines. On the other hand, resveratrol suppressed the expression of all. Alternatively, it activated BAD expression. Thus thyroxine induces checkpoint gene expression which may promote proliferation in cancer cells. Alternatively, resveratrol reverses the stimulatory effects of thyroid hormone to induce anti-proliferation. Conclusion: These findings provide new insights into the antagonizing effect of resveratrol on the thyroxine-induced expression of checkpoint genes and proliferative genes in oral cancers. Keywords: L-thyroxine, Resveratrol, Checkpoint genes, Oral cancer

Osteoconduction is an important consideration for fabricating bio-active materials for bone regeneration. For years, hydroxyapatite and β-calcium triphosphate (β-TCP) have been used to develop bone grafts for treating bone defects. However, this material can be difficult to handle due to filling material sagging. High molecular weight hyaluronic acid (H-HA) can be used as a carrier to address this problem and improve operability. However, the effect of H-HA on bone formation is still controversial. In this study, low molecular weight hyaluronic acid (L-HA) was fabricated using gamma-ray irradiation. The viscoelastic properties and chemical structure of the fabricated hybrids were evaluated by a rheological analysis nuclear magnetic resonance (NMR) spectrum. The L-MH was mixed with H-HA to produce H-HA/L-HA hybrids at ratios of 80:20, 50:50 and 20:80 (w/w). These HA hybrids were then combined with hydroxyapatite and β-TCP to create a novel bone graft composite. For animal study, artificial bone defects were prepared in rabbit femurs. After 12 weeks of healing, the rabbits were scarified, and the healing statuses were observed and evaluated through micro-computer tomography (CT) and tissue histological images. Our viscoelastic analysis showed that an HA hybrid consisting 20% H-HA is sufficient to maintain elasticity, however, the addition of L-HA dramatically decreases the dynamic viscosity of the HA hybrid. Micro-CT images showed that the new bone formations in the rabbit femur defect model treated with 50% and 80% L-HA were 1.47 (p &lt, 0.05) and 2.26 (p &lt, 0.01) times higher than samples filled with HA free bone graft. In addition, a similar tendency was observed in the results of HE staining. These results lead us to suggest that the material with an H-HA/L-HA ratio of 50:50 exhibited acceptable viscosity and significant new bone formation. Thus, it is reasonable to suggest that it may be a potential candidate to serve as a supporting system for improving the operability of granular bone grafts and enhancing new bone formations.

Objective We investigated the importance of reactive oxygen species (ROS) on developing gingival overgrowth (GO) and then introduced the antioxidant strategy to prevent, or even reduce GO. Background Gingival overgrowth is a common side effect of the patients receiving cyclosporine A (CsA), an immune suppressant. Although it has been broadly investigated, the exact pathogenesis of the induced GO is still uncertain. Methods We cultured human primary gingival fibroblasts and used animal model of GO to investigate the ameliorative effects of antioxidants on CsA-induced GO. To examine the CsA-induced oxidative stress, associated genes and protein expression, and the overgrown gingiva of rats by using immunocytochemistry, confocal laser scanning microscopy, real-time PCR, ELISA, gelatin zymography, gingival morphological, and immunohistochemical analysis. Results We found for the first time that ROS was responsible for the CsA-induced oxidative stress and TGF-β1 expression in human primary gingival fibroblasts, as well as the GO of rats. The antioxidants (oxidative scavenger of vitamin E and an antioxidative enzyme inducer of hemin) ameliorated CsA-induced pathological and morphological alterations of GO without affected the CsA-suppressed il-2 expression in rats. CsA-induced oxidative stress, HO-1, TGF-β1, and type II EMT were also rescued by antioxidants treatment. Conclusions We concluded that CsA repetitively stimulating the production of ROS is the cause of CsA-GO which is ameliorated by treating antioxidants, including vitamin E and sulforaphane. Furthermore, the immunosuppressive effect of CsA is not interfered by antioxidant treatments in rats. This finding may thus help the clinician devise better prevention strategies in patients susceptible to GO.

Low-molecular-weight hyaluronic acid (LMWHA) was integrated with superparamagnetic Fe3O4 nanoparticles (Fe3O4 NPs). The size distribution, zeta potential, viscosity, thermogravimetric and paramagnetic properties of the LMWHA-Fe3O4 NPs were systematically examined. For cellular experiments, MCF7 breast cancer cell line was carried out. In addition, the cell targeting ability and characteristics of the LMWHA-Fe3O4 NPs for MCF7 breast cancer cells were analyzed using the thiocyanate method and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The experimental results showed that the LMWHA-Fe3O4 NPs were not only easily injectable due to their low viscosity, but also exhibited a significant superparamagnetic property. Furthermore, the in vitro assay results showed that the NPs had negligible cytotoxicity and exhibited a good cancer cell targeting ability. Overall, the results therefore suggest that the LMWHA-Fe3O4 NPs have considerable potential as an injectable agent for enhanced magnetic resonance imaging (MRI) and/or hyperthermia treatment in breast cancer therapy.

Periodontitis is an inflammatory disease of the supporting tissues of the teeth induced by periodontopathic bacteria that results in the progressive destruction of periodontal tissues. Treatment of periodontitis is painful and time-consuming. Recently, herbal medicines have been considered for use in treating inflammation-related diseases, including periodontitis. Resveratrol and its derivative 2,3,5,4'-tetrahydroxystilbene-2-O-β-glucoside (THSG), a polyphenol extracted from Polygonum multiflorum, have anti-inflammatory properties and other medical benefits. Here, we highlight the importance of resveratrol and its glycosylated derivative as possible complementary treatments for periodontitis and their potential for development as innovative therapeutic strategies. In addition, we present evidence and discuss the mechanisms of action of resveratrol and THSG on periodontitis, focusing on Porphyromonas gingivalis-induced inflammatory responses in human gingival fibroblasts and animal modeling of ligature-induced periodontitis. We also illuminate the signal transduction pathways and the cytokines involved.

Background This study aimed to investigate the regenerative effects of 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside (THSG)-treated human dental pulp stem cells (DPSC) on the healing of experimental periodontal defects in rats. Methods The maxillary first molars of 30 male Sprague-Dawley rats were extracted, and after healing, bilateral periodontal defects were surgically created mesially in second molars. The defects were treated with Matrigel (as control), DPSC, or DPSC + THSG. After 2 weeks, the healed defects were evaluated using microcomputed tomography and through histological and immunohistochemical analyses. Results In the microcomputed tomography analysis, more new bone formation in the DPSC and DPSC + THSG groups was observed compared with the control group. The periodontal bone supporting ratio in site with DPSC + THSG was significantly higher than that in DPSC. Histologically, an enhanced new bone formation and more significant periodontal attachment were observed in the DPSC + THSG group. The expression levels of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), and osteopontin (OPN) in the DPSC + THSG group were significantly greater than those in other groups. Conclusions THSG-revolutionized DPSCs significantly shortened the regenerative period of periodontal defects by enhancing the cell recruitment and possibly the angiogenesis in rat models, which illustrate the critical implications for a clinical application and provide a novel tactic for periodontitis treatment.

Nano-diamino-tetrac (NDAT), a tetraiodothyroxine deaminated nano-particulated analog, has shown to inhibit expression of pro-inflammatory genes. NDAT inhibits expression of programmed death-ligand 1 (PD-L1). On the other hand, in addition to inhibiting inflammatory effect, the stilbene, resveratrol induces expression of cyclooxygenase-2 (COX-2) and its accumulation. Sequentially, inducible COX-2 complexes with p53 and induces p53-dependent anti-proliferation. In current study, we investigated mechanisms involved in combined treatment of NDAT and resveratrol on anti-proliferation in human oral cancer cells. Both resveratrol and NDAT inhibited expression of pro-inflammatory IL-1β and TNF-α. They also inhibited expression of CCND1 and PD-L1. Both resveratrol and NDAT induced BAD expression but only resveratrol induced COX-2 expression in both OEC-M1 and SCC-25 cells. Combined treatment attenuated gene expression significantly compared with resveratrol treatment in both cancer cell lines. Resveratrol reduced nuclear PD-L1 accumulation which was enhanced by a STAT3 inhibitor, S31-201 or NDAT suggesting that NDAT may inactivate STAT3 to inhibit PD-L1 accumulation. In the presence of T4, NDAT further enhanced resveratrol-induced anti-proliferation in both cancer cell lines. These findings provide a novel understanding of the inhibition of NDAT in thyroxine-induced pro-inflammatory effect on resveratrol-induced anticancer properties.

The common methods for synthesizing calcium phosphates include solid-state reaction, hydrothermal, sol–gel, and wet precipitation. The purpose of this study was to prepare various calcium phosphate bioceramics through a continuous reactor equipped with a static mixer. The precursors, amorphous calcium phosphate (ACP), and poor crystal hydroxyapatite (PC-HAp) were prepared using calcium and phosphate ion-containing solutions by adjusting the pH and the [Ca]/[P] input ratio. The phase transformation from precursors to HAp, alpha-tricalcium phosphates (α-TCP), beta-tricalcium phosphate (β-TCP), or biphasic calcium phosphate (BCP) was dependent on the sintering temperature.

The purpose of this in vivo study was to evaluate the effect of human dental pulp stem cells (hDPSCs) on various resorbable calcium sulfate/calcium phosphate bone grafts in bone regeneration. Granular particles of calcium sulfate dehydrate (CSD), α-calcium sulfate hemihydrate/amorphous calcium phosphate (α-CSH/ACP), and CSD/β-tricalcium phosphates (β-TCP) were prepared for in vitro dissolution and implantation test. The chemical compositions of specimen residues after dissolution test were characterized by XRD. The ratios of new bone formation for implanted grafts/hDPSCs were evaluated using mandible bony defect model of Lanyu pig. All the graft systems exhibited a similar two-stage dissolution behavior and phase transformation of poor crystalline HAp. Eight weeks post-operation, the addition of hDPSCs to various graft systems showed statistically significant increasing in the ratio of new bone formation (p

The degradation of Mirage Bioresorbable Microfiber Scaffold was evaluated in vitro and in vivo. The degradation in polymer molecular weight (MW), strut morphology, and integrity was accessed using gel permeation chromatography (GPC), X‐ray micro‐computed tomography (micro‐CT) evaluation. To simulate the physiological degradation in vitro, scaffolds were deployed in silicone mock vessels connected to a peristaltic pumping system, which pumps 37°C phosphate‐buffered saline (PBS, pH 7.4) at a constant rate. At various time points (30D, 60D, 90D, 180D, 270D, and 360D), the MW of microfibers decreased to 57.3, 49.8, 36.9, 13.9, 6.4, and 5.1% against the baseline. The in vivo degradation study was performed by implanting scaffolds in internal thoracic arteries (ITAs) of mini‐swine. At the scheduled sacrifice time points (30D, 90D, 180D, 270D, 360D, and 540D), the implanted ITAs were excised for GPC analysis; the MW of the implanted scaffolds dropped to 58.5, 34.7, 24.8, 16.1, 12.9, and 7.1, respectively. Mass loss of scaffolds reached 72.4% at 540D of implantation. Two stages of hydrolysis were observed in in vitro and in vivo degradation kinetics, and the statistical analysis suggested a positive correlation between in vivo and in vitro degradation. After 6 months of incubation in animals, significant strut degradation was seen in the micro‐CT evaluation in all sections as strut fragments and separations. The micro‐CT results further confirmed that every sample at 720D had X‐ray transmission similar to surrounding tissue, thereby indicating full degradation within 2 years. © 2017 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1842–1850, 2018.

The aim of the study was to investigate the efficacy of the addition of funoran to xylitol chewing gum in dental plaque. In a double-blinded randomized controlled clinical trial, 36 health adults (21–30 years old), who volunteered after informed consent, with >105 colony-forming units/ml mutans streptococci (MS) at baseline, were assigned randomly into one of three parallel study groups: xylitol+funoran gum (group A), sucrose gum group (group B), and control group (no gum have been provided; group C). The pH value, flash weight, and MS of dental plaque were recorded at baseline and after 2 weeks of treatment. A statistically significant reduction (p

Thyroid hormone, L-thyroxine (T4), induces inflammatory genes expressions and promotes cancer growth. It also induces expression of the checkpoint programmed death-ligand 1 (PD-L1), which plays a vital role in cancer progression. On the other hand, resveratrol inhibits inflammatory genes expressions. Moreover, resveratrol increases nuclear inducible cyclooxygenase (COX)-2 accumulation, complexes with p53, and induces p53-dependent anti-proliferation. In this study, we investigated the effect of T4 on resveratrol-induced anti-proliferation in oral cancer. T4 increased the expression and cytoplasmic accumulation of PD-L1. Increased expressions of pro-inflammatory genes, interleukin (IL)-1β and transforming growth factor (TGF)-β1, were shown to stimulate PD-L1 expression. T4 stimulated pro-inflammatory and proliferative genes expressions, and oral cancer cells proliferation. In contrast, resveratrol inhibited those genes and activated anti-proliferative genes. T4 retained resveratrol-induced COX-2 in cytoplasm and prevented COX-2 nuclear accumulation when resveratrol treated cancer cells. A specific signal transducer and activator of transcription 3 (STAT3) inhibitor, S31-201, blocked T4-induced inhibition and restored resveratrol-induced nuclear COX-2 accumulation. By inhibiting the T4-activated STAT3 signal transduction axis with S31-201, resveratrol was able to sequentially reestablish COX-2/p53-dependent gene expressions and anti-proliferation. These findings provide a novel understanding of the inhibitory effects of T4 on resveratrol-induced anticancer properties via the sequential expression of PD-L1 and inflammatory genes.

This study examines the relationship between the retention force and natural frequency of dental posts cemented with zinc phosphate cement. Forty-two decoronated maxillary incisors were collected and embedded in resin blocks. The 7-mm post spaces were prepared for all test samples prior to cementing the 13-mm Para-Posts with zinc phosphate cement. The natural frequency values and retention forces of the zinc phosphate cement–cemented Para-Posts in various liquid/powder mixing ratios were measured. Thereafter, the natural frequency values of the zinc phosphate cement–cemented posts were continuously detected during ultrasonic vibration. Moreover, both the natural frequency values and the dislodgement forces in response to ultrasonic vibrations were measured for the pretreated post samples. Results showed that the natural frequency values of the posts significantly decreased from 8.8 ± 0.8 to 5.0 ± 0.5 kHz ( P < 0.05) before and after ultrasound treatment, respectively. The natural frequency values and the dislodgement forces of tested posts had a highly linear relationship ( R2 = 0.99, P < 0.05). These findings suggest that natural frequency is a variable for monitoring the stability status of zinc phosphate cement–cemented dental posts.

Typical electrospun polylactic acid (PLA) membranes revealing potential hydrophobicity and inflammation from acid release during degradation are major drawbacks as an ideal guided tissue regeneration (GTR) barrier. This study investigated the in vitro degradation properties of electrospun PLA/beta-tricalcium phosphate (β-TCP) membranes treated by polyethylene oxide dip-coating process. After surface modification, the membranes revealed good wettability in contact angle measurement. The addition of β-TCP can render good pH buffering properties for electrospun PLA membranes during the in vitro degradation test. The mechanical properties of the hybrid membrane showed no significant difference in suture pullout force at a dried or wetted state. For cell adhesion and proliferation, the membranes with hydrophilicity can enhance the cell attachment at early stage. Overall, these results show that electrospinning combined with dip coating is a feasible processing technology for producing hydrophilic fibrous GTR membranes. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.

The aim of this study was to develop an antibacterial polyelectrolyte complex (PEC) scaffold for treating dental bone defects. The PEC scaffold was composed of chitosan (CS), γ-polyglutamic acid (γ-PGA), and carboxy-methyl-cellulose (CMC). The resulted network structures formed via electrostatic crosslinking were characterized by using FTIR, gel content, equilibrium swelling ratio, volume change, and SEM test. The antibacterial property, cell cytotoxicity, and in vivo biocompatibility tests were conducted according to an agar diffusion method, ISO10993-5, and ISO 10993-6, respectively. The resulted specimens showed an interconnected pore structure with pore sizes ranging 100–500 μm. The equilibrium swelling ratio, volume change, and antibacterial property were inversely proportional to the gel content. The PEC-2 scaffold composed of 8 wt.% CS, and 2 wt.% γ-PGA + 2 wt.% CMC had more-suitable gel properties (gel content of 55.3 ± 1.1 wt.% and volume change of 97.7 ± 1.4 v/v%) with inhibition zones of 14.4 ± 0.3 mm for Escherichia coli and 13.0 ± 0.7 mm for Staphylococcus aureus. The cytotoxicity and cell attachment tests of the PEC scaffolds showed satisfactory cell compatibility. Moreover, the in vivo biocompatibility test of the PEC scaffolds revealed little foreign body reaction. For this reason, the newly developed antibacterial PEC scaffold may be a good alternative for dental applications.

To improve the bioactivity of titanium surfaces, glow discharge was used to facilitate collagen grafting on titanium disks. Titanium test specimens were pre-treated by glow discharge fed with a mixture of argon and allylamine (AA) gases. Treated titanium disks were then grafted with type I collagen using glutaraldehyde (GA) as a crosslinking agent. The surfaces of collagen-grafted titanium disks were evaluated using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). MG-63 osteoblast-like cells were cultured on the grafted titanium surfaces to examine the effect of collagen grafting in terms of cell morphology. Our results demonstrated that collagen component elements could be detected on the titanium surfaces. Morphology of the cells on the surfaces of collagen-grafted titanium disks indicated differentiation. These findings showed that type I collagen could be successfully grafted onto titanium surfaces using glow discharge technology, with enhanced biofunctionality demonstrated on osteoblastic cells.

Periodontitis, a chronic infection by periodontopathic bacteria, induces uncontrolled inflammation, which leads to periodontal tissue destruction. 2,3,5,4′-Tetrahydroxystilbene-2-O-beta-glucoside (THSG), a polyphenol extracted from Polygoni Multiflori, reportedly has anti-inflammatory properties. In this study, we investigated the mechanisms of THSG on thePorphyromonas gingivalis-induced inflammatory responses in human gingival fibroblasts and animal modeling of ligature-induced periodontitis. Human gingival fibroblast cells were treated with lipopolysaccharide (LPS) extracted fromP. gingivalisin the presence of resveratrol or THSG to analyze the expression of TNF-α, IL-1β, and IL-6 genes. Increased AMP-activated protein kinase (AMPK) activation and SirT1 expression were induced by THSG. Treatment of THSG decreased the expression of LPS-induced inflammatory cytokines, enhanced AMPK activation, and increased the expression of SirT1. In addition, it suppressed the activation of NF-κB when cells were stimulated withP. gingivalisLPS. The anti-inflammatory effect of THSG and P. Multiflori crude extracts was reproduced in ligature-induced periodontitis animal modeling. In conclusion, THSG inhibited the inflammatory responses ofP. gingivalis-stimulated human gingival fibroblasts and ameliorated ligature-induced periodontitis in animal model.

Objective Interleukin-1β (IL-1β) is an inflammatory molecule of the dental pulp. IL-1β stimulates cyclooxygenase-2 (COX-2) and prostaglandins production of pulp cells and affects the pulpal inflammation and repair. However, the effects of IL-1β on Monocyte Chemotactic Factor-1 (MCP-1) of dental pulp cells and its relation to transforming growth factor β-activated kinase-1 (TAK1), PI3K/Akt, and MEK/ERK signaling and COX activation are not fully clear. Design Human dental pulp cells were exposed to IL-1β with/without pretreatment and co-incubation by aspirin (a COX inhibitor), 5z-7-oxozeaenol (a TAK1 inhibitor), LY294002 (a PI3K/Akt inhibitor) or U0126 (a MEK/ERK inhibitor). Viable cell number was evaluated by MTT assay. MCP-1 mRNA expression was tested by reverse transcriptase-polymerase chain reaction (RT-PCR). MCP-1 and COX-2 protein expression was studied by western blot. MCP-1 in the culture medium was measure by ELISA. Results IL-1β showed little cytotoxicity to pulp cells. It stimulated MCP-1 mRNA and protein expression and MCP-1 secretion. Aspirin, U0126, LY294002 and 5z-7-oxozeaenol attenuated the IL-1β-induced MCP-1 expression. In addition, 5z-7-oxozeaenol, LY294002, U0126 and aspirin prevented the IL-1β-induced MCP-1 secretion of pulp cells. Conclusion These results indicate that IL-1β may be involved in the pulpal inflammatory and healing processes by inducing MCP-1 expression and secretion. These events are related to differential activation of TAK1, PI3K/Akt and MEK/ERK 1/2 signaling and COX activation. These results are important for future pharmacologic intervention of pulpal inflammatory diseases.

Glycosaminoglycans (GAGs), in particular chondroitin sulfate, are an accepted marker of chondrogenic cells. In this study, a cell-based sulfated GAG assay for identifying the chondrogenesis of mesenchymal stem cells was developed. Based on fluorescent staining using safranin O and 4’,6-diamidino-2-phenylindole (DAPI), this method was highly sensitive. The results were both qualitative and quantitative. The method is suitable for identifying the chondrogenic process and also for screening compounds. The method may be helpful for discovering novel bioactive compounds for cartilage regeneration.

In this study, supercritical fluid (SCF) technology is discussed in relation to biomaterial processing, especially the fabrication and processing of alloplastic bone graft. SCF offers excellent extraction properties for some compounds because of its favorable diffusivity, viscosity, zero surface tension, liquidlike density and solvating power, and other physical properties. The most desirable SCF solvent for extraction is supercritical carbon dioxide (SCCO 2 ), which is nontoxic, nonflammable, inexpensive, friendly to mankind, and environmentally benign and has mild supercritical conditions (T c = 31.2 °C, P c = 7.386 MPa). For the porous structure of porcine vertebra with its content of lipids, proteins, and inorganic substances in the cells and intercellular matrix, SCCO 2 combined with ethanol or glutaraldehyde (GA) is used to prepare novel porcine-derived bone grafts in three supercritical settings and one subcritical condition for control comparison. The biocompatibility of these novel bone grafts was tested with human MG63 osteoblast-like cells and mouse fibroblast 3T3 cells by MTT assay. The results revealed that materials processed by SCCO 2 combined with both ethanol and GA were not cytotoxic and allowed the differentiation and proliferation of test cells. The good performances of these novel bone grafts can be explained by the characteristics of SCF. Applications of SCF in biomaterials are very promising for bone regeneration and tissue engineering. Additional advanced in vitro and in vivo studies must be performed in the future for optimization.

In this study, the barrier properties of Hf and nitrogen incorporated Hf films were investigated by Cu/Hf-N/Si structure. Hafnium and hafnium nitride films were prepared by reactive rf-magnetron sputtering on blank silicon wafers. The barrier properties were evaluated by sheet resistance, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 100.98 @m@W-cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as hcp-Hf->fcc-HfN. The thermal stability of Cu/Hf/Si and Cu/HfN"0"."4"7/Si contact system is evaluated by thermal stressing at various annealing temperatures. Nitrogen incorporated Hf films possess better barrier performance than sputtered Hf films. For the Cu/Hf/Si contact system, the interfacial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550 ^oC for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600 ^oC for 30 min. The Hf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. The Cu/HfN"0"."4"7/Si is fairly stable up to annealing at 650 ^oC for 30 min. In addition, no copper-hafnium and copper silicide compounds are found. Diffusion resistance of nitrogen-incorporated Hf barrier is more effective. The thermal stabilities of Cu/HfN"0"."4"7/n^+-p junction diodes are enhanced by nitrogen incorporation. The Cu/Hf/n^+-p junction diodes result in large reverse-biased junction leakage currents after annealing at 500 ^oC for 30 min. On the other hand, Nitrogen incorporated Hf diffusion barriers retained the integrity of junction diodes up to 550 ^oC with lower reverse current densities. Phase transformation of hafnium-based barrier films with nitrogen incorporation are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. Nitrogen incorporated hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, and thus improve the thermal stability of barrier layer.

Introduction: The objective of this in vitro study is to evaluate the effective and long-term occlusion of dentinal tubules using a novel calcium lactate phosphate (CLP) based desensitizing agent. Methods: Dentin disks (n = 9) were pre-etched using 1 M lactic acid for 30 s and individually treated with Colgate® Pro-Relief™ paste, CLP paste, and double distilled water (ddH2O) by a rubber-cupped handpiece. Dentin disks were analyzed under optical micrographs for pre-treatment, directly after treatment, and 14 days post-treatment. One-way ANOVA and post-hoc Tukey’s test were used to determine whether there were any statistically significant differences in dentinal tubule diameter. Results: A significant decrease occurred in the mean tubule diameter for dentin disks treated with CLP paste. A decrease was observed from 3.52 ± 0.83 µm to 2.62 ± 0.42 µm right after treatment, further decreasing to 1.71 ± 0.45 µm after immersion in artificial saliva for 14 days (p < 0.05). Conclusions: The results suggest that the CLP based desensitizing paste has remineralization properties and provides instant and lasting effectiveness in dentinal tubule occlusion.

The aims of this study were to observe the release of fluoride ions (F-) from GC-Fuji Lining-LC(R) glass-ionomer cement, to assess the diffusion process, and to measure fluoride diffusivity (D) in the set cement. Specimens of various dimensions and shapes, ranging from discs to cylindrical rods, were fabricated for both open and embedded modes of testing. In the open mode studies, specimens with different surface to volume ratios were selected and immersed in 37 degrees C distilled water. In the embedded mode studies, only one diametral surface of the rod-shaped specimens of different lengths and diameters was exposed. F- concentration was measured using a fluoride electrode. The storage solution was analysed at predetermined intervals hourly, daily, and weekly (up to 10 weeks). Immediately after each sampling, the old storage solution was discarded and replaced with new distilled water. F- release from the set cements was detectable (0.4-3.8 ppm, varied with sample geometry), even after a 10-week sampling interval. F- release was greater in ground set cements (0.37 ppm/mg powder) than in control samples of unmixed powder (0.01 ppm/mg powder) immersed for 1 h. Two mechanisms for F- release were proposed. One was short-term and involved rapid dissolution from the cement surface. The other was more gradual and resulted in the sustained diffusion of ions through the bulk cement, which can be modelled by applying a mathematical technique known as separation of variables to Fick's Second Law of Diffusion. The mean D of F- in embedded set cements of glass-ionomer was (1.4+/-0.5)x10-11 cm2/s, with higher apparent D observed in open mode samples [(7.6+/-1.4)x10-11 cm2/s].

A laser thermoacoustic technique was innovated to evaluate laser-induced acoustic emissions (AEs) in experimental dental composites aged with 75% ethanol solution. Experimental composite systems of 75/25 BisGMA/TEGDMA resin filled with 0, 12.6, 30.0, and 56.5 vol% of 8-μm silanized and unsilanized BaSiO 6 were analyzed. The sample size was 4.65 mm (diameter)×0.5 mm (thick). Aging effects of immersing in 75% ethanol for up to 14 h on AEs were then evaluated. A continuous-wave CO 2 laser was used to heat the samples. Acoustic emissions were collected as a function of filler fraction, laser power, silanization, and immersion time. Onset of burst-pattern acoustic signals characteristic of fracturing occurred at different laser powers for different tested groups. Acoustic emissions generally increased with laser power, in which lower laser powers produced low-amplitude (45–50 dB) signals; the amplitude distribution (50–85 dB) became more extensive as laser powers increased. After immersion, the lower laser powers could produce the same phenomenon. The higher the filler fraction, the fewer AEs generated. A large percentage AE reduction due to silanization was noted as a function of filler fraction. Unsilanized specimens showed more thermal damages than did silanized ones.

Introduction This study evaluates the radiopacity and cytotoxicity of Portland cements containing a radiopacifier of bismuth oxide (Bi 2 O 3 ) with yttria-stabilized zirconia (YSZ) dopant. Methods Various radiopacifier powders of Bi 2 O 3 with 0%, 15%, 30%, and 100% YSZ dopant were prepared by solid-state reaction at 700°C for 12 hours and characterized by x-ray diffraction. Portland cement/radiopacifier/calcium sulfate (75/20/5) were mixed and set by deionized water. Changes in radiopacity and in vitro cell viability of the hydrated cements were assessed. An average of 6 measured equivalent thickness of aluminum (N = 6) capable of producing similar radiographic density was recorded. The cytotoxicity of each material was determined in MC3T3 E1 cell-based methyl-thiazol-tetrazolium assay. Results The x-ray diffraction patterns of YSZ doped Bi 2 O 3 are different from those of pure Bi 2 O 3 and YSZ. The cement-containing radiopacifier of Bi 2 O 3 /YSZ (85/15) presented significantly greater radiopacity ( P 2 O 3 . The mouse osteoblastic cell (MC3T3-E1) viabilities of these 2 groups were statistically similar ( P Conclusions The radiopacifier of Bi 2 O 3 /YSZ (85/15) reveals higher radiopacity but similar cell viability when compared with pure Bi 2 O 3 . It shows potential use as an alternative radiopacifier in root-end filling materials.

The aim of this study was to assess the cryoprotective effect of static magnetic fields (SMFs) on human erythrocytes during the slow cooling procedure. Human erythrocytes suspended in 20% glycerol were slowly frozen with a 0.4-T or 0.8-T SMF and then moved to a −80°C freezer for 24 hr. The changes in survival rate, morphology, and metabolites of the thawed erythrocytes were examined. To understand possible cryoprotective mechanisms of SMF, membrane fluidity and dehydration stability of SMF-exposed erythrocytes were tested. For each test, sham-exposed erythrocytes were used as controls. Our results showed that freezing coupled with 0.4-T or 0.8-T SMFs significantly increased the relative survival ratios of the frozen-thawed erythrocytes by 10% and 20% (p

The purpose of this study was to analyze the IR spectra of a liquid simulating food and an artificial saliva following exposure to resin composites.Fourier transform infrared (FTIR) spectroscopy was used to analyze two solutions in which three commercially available dental composites (Marathon One, Den-Mat Co.; Z100, 3M Co.; Herculite XRV, Kerr Co.) were stored. The solutions used were: a food simulating fluid, 75 vol% ethanol/water, and an artificial saliva, Moi-Stir (Kingwood Labs., Inc.). Specimens (4.3 mm diam. X 2 mm thick) of the three resin composites were stored at 37 degrees C in 60 mL of either Moi-Stir or the 75% ethanol solution for 7, 14, and 30 d. The FTIR spectra were obtained using a liquid sample ATR (attenuated total reflection) cell.No obvious leachable materials were seen from any of the composite specimens stored in artificial saliva up to 30 d of immersion. For the composites stored in ethanol, the observed spectra revealed increases in the principal absorption bands for the components of the three composite systems. Methacrylate skeletal vibrations (1015-815 cm(-1)) and -CH3 alkane, C-H asymmetrical deformation vibrations (1520-1460 cm(-1)) appeared after 14 d of storage. A very strong peak characteristic of the aliphatic C=C moiety (1640 cm(-1)) and carbonyl C=O (1730 cm(-1)) occurred after 14 d. The peak heights of these two functional bands increased as a function of time and after 30 d of storage were approximately 5-7 times those produced after 7 d. Irregular O-H bands (3500-3300 cm(-1)) were also observed after 30 d in ethanol.Irreversible processes such as the leaching of components occurs in the presence of ethanol. This phenomenon may contribute to irreversible material degradation.

In this study, hydrogels composed of polyethyleneimine (PEI) and poly(vinyl pyrrolidone) K90 (PVP) cross-linked with various concentrations (0, 0.125, 0.25 and 0.5%) of glutaraldehyde were evaluated as a hydrogel filler for the local delivery of lidocaine after tooth extraction. The drug-release kinetics, swellability, cytotoxicity and wound healing after tooth extraction of these non-cross-linked and cross-linked PEI-PVP hydrogels were examined in male beagles and compared to values using Spongostan(®). Results demonstrated that the extent of cross-linking influenced the swelling of the resulting hydrogel, but the drug-release rates were similar. No significant changes were observed in gingival fibroblasts in contact with the PEI- PVP hydrogels or Spongostan(®). In the in vivo study, PEI-PVP hydrogels showed good retention in the socket for 2 days and showed comparable wound-healing rates within 2 weeks with those of Spongostan(®). In conclusion, PEI-PVP hydrogels are suitable for use as socket-dressing materials, and the release of local anaesthesia from PEI-PVP hydrogels can be sustained for a desirable period of time to prevent pain after a tooth extraction.

The objective of this study was to investigate the antibacterial, biocompatibility, and mechanical properties of mineral trioxide aggregate (MTA) set using a calcium lactate gluconate (CLG) solution.ProRoot white MTA (WMTA) (Dentsply Tulsa Dental, Tulsa, OK) was used as the control group; MTA-like cement was prepared by mixing Portland cement/bismuth oxide/calcium sulfate (75/20/5) as the experiment group. A solution of 23.1 wt% CLG was used as a hydration accelerant and was compared with deionized water (DDW). Changes in pH values, antibacterial properties, in vitro cell viability, and diametral tensile strength (DTS) of the hydrated cements were assessed.Like WMTA, pH values for the MTA-like cement set using DDW and the CLG solution showed minor but statistically significant differences (P.05). The antibacterial effects of hydrated specimens set by DDW and CLG against Streptococcus mutans assessed with an in vitro tube dilution test showed a significant difference in the early hydration time but no significant difference after 60 minutes (P.05). A mouse osteoblastic cell (MC3T3-E1)-based MTT assay revealed that WMTA set using CLG had significantly higher cell viability than that set using DDW (P.05). The DTS test for hydrated MTA-like cement with different liquids showed a significant difference on day 1 but no statistical difference on day 21.The results suggest that using a CLG solution as the hydration accelerant may enhance the biocompatibility but not compromise WMTA's antibacterial and mechanical properties.

Introduction Mineral trioxide aggregate (MTA) fulfills many of the ideal properties of a root end filling material and repair material for furcal perforation. However, its low cohesive property often makes it difficult to handle. To improve the handling properties of MTA root canal filling materials, MTA-like cement was made, and calcium lactate gluconate (CLG) aqueous solution was used to shorten the setting time and enhance the paste viscosity. Methods CLG solution was prepared by mixing lactic acid, glucono delta lactone, and calcium oxide by wet process. The crystalline property of the CLG powder was characterized by x-ray diffraction. The MTA-like cements were prepared by mixing Portland cement/bismuth oxide/gypsum (75/20/5); ProRoot white MTA (Dentsply Tulsa Dental, Tulsa, OK) was used as a control group. The influence of various liquid phases on initial setting time, handling properties, and pH value were investigated by a Vicat needle, questionnaire of operational hand feel, and pH meter, respectively. Results By using 23.1wt% CLG solutions as a liquid phase, the setting time of white MTA was significantly decreased from 155.5 ± 5.0 to 12.3 ± 2.5 minutes. The pH values for hydrated white MTA with deionized water and 23.1 wt% CLG solutions were 12.29 ± 0.02 and 11.81 ± 0.04 at 72 hours. Conclusions The results suggest that the addition of amorphous CLG-based liquid phase provides improvement in sealing ability as well as clinical manageability of dental filling materials.

The purpose of this study was to fine-tune the mechanical properties of high molecular-weight poly-L-lactic acid (PLLA), especially to increase its toughness without sacrificing too much of its original strength. Besides of its long degradation time, PLLA is usually hard and brittle, which hinders its usage in medical applications, i.e., orthopedic and dental surgery. Some modifications, such as the addition of plasticizers or surfactants/compatibilizers, are usually required to improve its original properties. PDLLA can degrade quickly due to its amorphous structure, thus shortening the degradation time of PLLA/PDLLA blends. Blends of biodegradable poly-L-lactic acid (PLLA) and poly-DL-lactic acid (PDLLA) or polycaprolactone (PCL), in addition to a third component, the surfactant-a copolymer of ethylene oxide and propylene oxide, were prepared by blending these three polymers at various ratios using dichloromethane as a solvent. The weight percentages of PLLA/PDLLA (or PCL) blends were 100%/0%, 80%/20%, 60%/40%, 50%/50%, 40%/60%, 20%/80% and 0%/100%, respectively. Physical properties such as the crystalline melting point, glass transition point (T(g)), phase behavior, degradation behavior, and other mechanical properties were characterized by thermogravimetric analysis, differential scanning calorimetry (DSC), infrared spectroscopy, gel permeation chromatography, and dynamic mechanical analysis (DMA). DSC data indicate that PLLA/PDLLA blends without the surfactant had two T(g)'s. With the addition of the surfactant, there was a linear shift of the single T(g) as a function of composition, with lower percentages of PLLA producing lower glass transition temperatures indicating that better miscibility had been achieved. DMA data show that the 40/60 PLLA/PDLLA blends without the surfactant had high elastic modulus and elongation, and similar results were observed after adding 2% surfactant into the blends. The 50/50 PLLA/PDLLA/2% surfactant blend had the highest elastic modulus, yield strength, and break strength compared with other ratios of PLLA/PDLLA/2% surfactant blends. The elongation at break of 50/50 PLLA/PDLLA was similar to that of PLLA. Again, the elongation at break of 50/50 PLLA/PDLLA/2% surfactant was almost 1.2-1.9 times higher than that of 50/50 PLLA/PDLLA and PLLA. Elongation of PLLA increased with the addition of PCL, but the strength decreased at the same time. In conclusions, adding PDLLA and surfactant to PLLA via solution-blending may be an effective way to make PLLA tougher and more suitable to use in orthopedic or dental applications.

The aim of this study was to analyse the leached moieties of dental composites after storage in ethanol and organic acids of plaque and further evaluate the resultant effect on the diametral tensile strength (DTS) of the composites. Three commercial composites were used: Bis-GMA-based Z100, Bis-GMA/UDMA-based Heliomolar, and Bis-MPEPP-based Marathon One. The solutions used were: 99.9% acetic acid, 99% propionic acid and 75% ethanol. Specimens (4 mm diam. x 2 mm thick) were stored at 37 degrees C in 3 mL of solution for up to 30 days. Gas chromatography/mass spectrometry was used to characterize the leached moieties and DTS of the specimens after immersion was evaluated. Data were analysed using ANOVA and Tukey LSD test. The eluted substances were not all the same in different solutions and composites but mostly increased with immersion time, and included diluents (TEGDMA and decamethacrylate) and some additives, such as an ultra-violet stabilizer (TINUVINP), plasticizers (dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate), initiator (triphenyl stibine), coupling agent (gamma-methacryloxypropyl trimethoxysilane), and phenyl benzoate. The chief polymerizing monomers were not found. More kinds of components were found in the acetic acid and ethanol groups studied. The fewest kinds and quantities of leached moieties were found for Bis-GMA specimens and then Bis-GMA/UDMA ones, most of which are diluent agents. Bis-MPEPP specimens leached the most substances, which were composed mostly of a short phenyl group chain structure. The BisGMA composite showed the highest DTS (54.8 +/- 5.7 MPa), which was not greatly affected by the length of storage. Bis-GMA/UDMA (36.2 +/- 6.8 MPa) and Bis-MPEPP (26.1 +/- 4.5 MPa) composites were significantly reduced (P < 0.05) after 30 days storage in the ethanol (35-50%), in the propionic acid (25-30%), and in the acetic acid (40-60%). Irreversible processes such as the leaching of components occur in fluids simulating an oral environment, which may contribute to irreversible material degradation, especially for non-Bis-GMA-based composites.

Introduction: The formation of a stereocomplex between PLLA and PDLA has been studied intensively because it increases the mechanical performance and thermal/hydrolytic resistance of polylactide-based materials; however, few studies have investigated the stereocomplex formation between PLLA and the (D-lactide)-containing PLLA copolymer. To investigate the effect of the D-lactide content of PLLA on the thermal behaviors and mechanical properties, (5D/95L) polylactide [(5D/95L)PLA], which contains a molar ratio of 5% of the D-form and 95% of the L-form of the monomer, and (15D/85L) polylactide [(15D/85L)PLA], which contains a molar ratio of 15% of the D-form and 85% of the L-form of the monomer, were used in a series of specimens. For the hydrolytic degradation test, the specimens were placed in 20-mL vials, which were filled with phosphate-buffered solution; the vials were allowed to stand at 57°C for 91 days in accordance with the ASTM F1635-95 (2000) standard test method for in vitro studies. The mechanical properties, thermal properties and crystallization behaviors were investigated using DSC and MTS, respectively. Results: The initial bending strength of the (5D/95L)PLA and (15D/85L)PLA were 35.4 and 31.1 N, respectively. After 1 week, the binding strength of the (5D/95L)PLA increased by 9.8%, and the binding strength of the (15D/85L)PLA decreased by 26%. In addition, the DSC curve of the (5D/95L)PLA demonstrated a higher melting temperature in the 1st week, and this Tc was observed in the DSC curve of the (5D/95L)PLA only during this time. The DSC curve of the (15D/85L)PLA was irregular. Discussion & Conclusions: In the (5D/95L)PLA, the recrystallization that occurred during the hydrolysis process was confirmed by the Tc and the increase in the bending strength. The stereocomplex crystallites may be formed in the (15D/85L)PLA during the degradation process. Because of the increase in the D-form monomer, the stereocomplexes were generated more easily and acted as nucleation sites. The PLLA crystal near the stereocomplex crystallites exhibited an incomplete structure, which led to a faster decrease in the bending strength. The low D-lactide content in the matrix of the PLLA did not form a stereocomplex crystallite because the surface area was not large enough to act as a nucleation site. However, the higher D-lactide-containing fraction formed a large stereocomplex crystallite. The (5D/95L)PLA demonstrated better thermal/hydrolytic resistance and mechanical stability than the (15D/85L)PLA.

The purpose of the present study was to evaluate the influences of titanium hydride on the formation of nanostructural titanium oxide by electrochemical treatment. The physico-chemical surface properties were investigated by scanning electron microscopy, cross-sectional transmission electron microscopy, thin film X-ray diffractometry, and X-ray photoelectron spectroscopy. Nanoporous structures were formed after anodization with cathodic pretreatments. The titanium hydride is formed by cathodic pretreatments. Titanium hydride was a sacrificial layer on titanium following anodization. The sacrificial layer has a γ-TiH 2 phase. The γ-TiH 2 is a tetragonal nanostructure and its lattice constant is a = 3.12 nm. Furthermore, it was formed within titanium matrices during cathodization. The nanostructural γ-TiH 2 decomposes after anodization. Furthermore, the nanoporous Ti formed by dissolution of TiH 2 was changed to nanoporous TiO 2 . The TiH 2 plays an important role in forming nanoporous TiO 2 . The triangle-like γ-TiH 2 was observed on the Ti matrix and grain boundary. In the γ-Ti matrix, an γ-Ti → γ-TiH 2 transition occurred during cathodization. The anodization with cathodic pretreatment not only produces titanium hydride layer, but also results in formation of nanostructural titanium oxide. Nanoporous titania can be enhanced osseointegration of implant such as orthopedic and dental implants.

X-ray photoelectron spectroscopy, grazing incident x-ray diffraction, transmission electron microscopy, and scanning electron microscopy were conducted to evaluate the effect of titanium hydride on the formation of nanoporous TiO2 on Ti during anodization. Nano-titanium-hydride was formed cathodically before anodizing and served as a sacrificial nanoprecipitate during anodization. Surface oxidation occurred and a multinanoporous structure formed after cathodic pretreatments followed by anodization treatment. The sacrificial nanoprecipitate is directly dissolved and the Ti transformed to nanoporous TiO2 by anodization. The formation of sacrificial nanoprecipitates by cathodic pretreatment and of the multinanostructure by anodization is believed to improve biocompatibility, thereby promoting osseointegration.

This study explores the effects of nano-(γ-TiH and δ-TiH 0.71 ) phases on the formation of nanoporous titanium oxide by anodization with HF pretreatment. The film characteristics were investigated by X-ray photoemission spectra, thin-film X-ray diffraction, transmission and electron scanning microscopy. Titanium hydride was a sacrificial barrier on titanium following HF pretreatment. The sacrificial barrier has nano-(γ-TiH and δ-TiH 0.71 ) phases. The titanium hydrides, γ-TiH and δ-TiH 0.71 , with a tetragonal and an orthorhombic structure, respectively, were formed within titanium matrices during cathodization. The nanophases are directly dissolved after anodization. Nanoporosity and oxidation followed from phase transformations and dissolution reactions of the nanophases. The nano-(γ-TiH and δ-TiH 0.71 ) phases have important roles in forming nanoporous TiO 2 . Anodization with HF pretreatment not only induces a titanium hydride layer, but also forms nanostructural titanium oxide. Particle-like γ-hydride and granular 8-hydride were observed on the Ti matrix and grain boundaries. The γ-hydride has a tetragonal structure with lattice constant a = 0.421 nm, and the 8-hydride has an orthorhombic structure with lattice constant a = 0.434 nm. The (γ + 8-hydride) microstructure was present on titanium grain boundaries. In the (a + γ) matrix, an α → γ → 8 transition occurred during cathodization. This result has never been previously reported. The surface that contains nanophases (γ + 8-hydride) is readily dissolved in alkaline solution, so anodization for a short time at room temperature yields nanoporous TiO 2 . This fact is exploited to avoid having to prepare porous TiO 2 by immersing Ti in an alkaline solution for a long time. As mentioned above, bioactive titanium with oxidation and nanostructures is believed to be capable of being prepared by anodization with HF pretreatment for a short time.