[Show abstract][Hide abstract] ABSTRACT: Background/purpose
The aim of this study was to investigate whether storage of extracted teeth in transportation solution for 24 hours has a negative effect on the cell density and mechanical properties of thawed pulp tissue extracted from frozen intact teeth.
Material and methods
Human premolars were kept in transportation solution for 0 hours or 24 hours. For each transportation time, the tested teeth were divided into two experimental groups: teeth that had been frozen in a magnetic programmed freezer (PF, n = 5) and in a traditional freezer at −20°C (TF, n = 5). The tested teeth were then stored at −150°C for 7 days. After thawing, the extracted pulp was subjected to a histological examination and mechanical testing.
Storage in transportation solution for 24 hours had no significant negative effects on the histological or mechanical properties of the pulp tissue extracted from the cryopreserved intact teeth. The elastic modulus of pulp from the teeth that had been frozen at −20°C was significantly higher (P < 0.05) in samples that had been pre-stored in transportation solution for 24 hours.
This study demonstrated that exposure to transportation solution for 24 hours followed by storage in a programmed freezer did not negatively affect the cell density or the elastic modulus of the pulp tissue.
Journal of dental sciences 09/2014; 9(3):244–248. · 0.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Successful and efficient cryopreservation of living cells and organs is a key clinical application of regenerative medicine. Recently, magnetic cryopreservation has been reported for intact tooth banking and cryopreservation of dental tissue. The aim of this study was to assess the cryoprotective effects of static magnetic fields (SMFs) on human dental pulp stem cells (DPSCs) during cryopreservation. Human DPSCs isolated from extracted teeth were frozen with a 0.4-T or 0.8-T SMF and then stored at -196 °C for 24 h. During freezing, the cells were suspended in freezing media containing with 0, 3 or 10% DMSO. After thawing, the changes in survival rate of the DPSCs were determined by flow cytometry. To understand the possible cryoprotective mechanisms of the SMF, the membrane fluidity of SMF-exposed DPSCs was tested. The results showed that when the freezing medium was DMSO-free, the survival rates of the thawed DPSCs increased 2- or 2.5-fold when the cells were exposed to 0.4-T or 0.8-T SMFs, respectively (p < 0.01). In addition, after exposure to the 0.4-T SMF, the fluorescence anisotropy of the DPSCs increased significantly (p < 0.01) in the hydrophilic region. These results show that SMF exposure improved DMSO-free cryopreservation. This phenomenon may be due to the improvement of membrane stability for resisting damage caused by ice crystals during the freezing procedure.
Electromagnetic Biology and Medicine 05/2014; · 0.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Novel poly-L-lactic acid (PLLA) microtube array membranes (MTAMs) with a porous wall structure were prepared by electrospinning. Porogen of polyethylene glycol (PEG) was mixed with PLLA and dissolved in a dichloromethane/dimethylformamide solvent. The solution dope was delivered to the outer layer of coaxial spinneret, while the PEG/polyethylene oxide (50/50 wt. %) aqueous solution was delivered to the core layer, to form arrays of core-shell fibers through an electrospinning process. Porogen was then washed off to produce array of microtubes with a porous wall structure. The morphology and physical properties of the MTAMs were characterized by scanning electron microscopy (SEM), a texture analyzer (TA), and a thermogravimetric analysis (TGA). With porogen content of 0~50 wt.%, pores, ranging from a few tens of nanometers to a few microns, were clearly seen in SEM micrographs for the surface of PLLA/PEG30-50 MTAMs after the washing process. However, porogen was effectively washed off only from PLLA/PEG30-50 MTAMs, thus their wall structure was transformed from a dense to porous one. PLLA/PEG MTAMs remained relatively hydrophobic. Young’s modulus of PLLA/PEG MTAMs decreased from 850 to 400 kPa, while the fracture work increased from 854 g.mm to a maximum value of 4478 g.mm for PLLA/PEG10. Permeation through MTAMs was conducted, and results revealed that only pores in the walls of PLLA/PEG30-50 MTAMs were well interconnected. Cumulative permeation increased with the PEG content. These results suggest that multifunctional porous PLLA MTAMs can potentially be used in medical applications, such as nerve regeneration conduits.
Current Nanoscience 02/2014; 10(2). · 1.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study evaluates the radiopacity and cytotoxicity of Portland cements containing a radiopacifier of bismuth oxide (Bi2O3) with yttria-stabilized zirconia (YSZ) dopant.
Various radiopacifier powders of Bi2O3 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.
The x-ray diffraction patterns of YSZ doped Bi2O3 are different from those of pure Bi2O3 and YSZ. The cement-containing radiopacifier of Bi2O3/YSZ (85/15) presented significantly greater radiopacity (P < .05) compared with pure Bi2O3. The mouse osteoblastic cell (MC3T3-E1) viabilities of these 2 groups were statistically similar (P < .05).
The radiopacifier of Bi2O3/YSZ (85/15) reveals higher radiopacity but similar cell viability when compared with pure Bi2O3. It shows potential use as an alternative radiopacifier in root-end filling materials.
Journal of endodontics 02/2014; 40(2):251-4. · 2.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Our goal was to investigate the relationship between clinical status and the presence of carious or periodontal pathogens among parent-child familial pairs. Clinical practices of risk assessment with consideration of familial pathogen interaction might reduce the need for therapy, improve patient outcomes, and ultimately reduce oral disease burden. Materials and Methods: In this study, we enrolled 30 parent-child pairs, with the children exhibiting complete deciduous dentition or mixed dentition with only permanent first molars. Clinical statuses were evaluated using caries and periodontal disease indicators, including the sum of decay and the number of missing or filled teeth (DMFT) for adults, decay, extraction caused by dental disease, and filled teeth (deft), for children, probing depth, and plaque control record (PCR). Supra- and sub-gingival bacteria were determined based on semi-quantitative measurements of microbial infection by using data from the Dentocult(®) SM test (caries-related organisms) and the PerioCheck(®) test (periodontal disease-related organisms).
No statistically significant relationship was detected between the prevalence of periodontal pathogens and that of cariogenic pathogens in the oral cavity. However, the clinical status of caries (DMFT) was negatively correlated with the clinical status of periodontal disease (pocket depth) in parents who were infected with dominant periodontal pathogens (r = -0.59, p<0.01). Parents' DMFT scores were positively correlated with children's deft and PCR scores. PCR and deft scores of children appeared to decrease significantly with the parent's pocket depth.
The study showed that the quantity of caries pathogens were not significant related to periodontal pathogens, but the caries clinical outcome is negative related with periodontal clinical outcome between familial pairs.
PLoS ONE 01/2014; 9(1):e87100. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: The aim of this study was to test whether damping factor is an adequate parameter for monitoring the status of the trabecular bone-implant interface. Materials and Methods: Implants were placed in epoxy resin with elastic moduli of 2,900, 210, and 1.4 MPa to simulate cortical bone, cancellous bone, and connective tissue, respectively. Resonance frequency and damping factor (DF) values of the tested implants were measured using vibration analysis. An impulse force was used to induce vibration within implants. The DF values of the tested implants were calculated from the obtained frequency spectrum using a half-power method. The resulting data were analyzed to test the statistical effects of the cortical height and trabecular status on the DF values of the sample implants. Results: When the simulated tissue at the implant-bone interface changed from connective tissue to bone, the detected DF value decreased markedly. In addition, the mean DF value of the tested implants increased significantly (P < .05) from 0.043 ± 0.008 when the elastic modulus of the surrounding resins was 2,900 MPa to 0.114 ± 0.018 when the modulus was 1.4 MPa. Furthermore, when the tested implants were firmly fixed with 2 mm of simulated cortical bone, the alternation of healing tissue at the trabecular bone area could be detected by the DF method. Conclusion: DF is a sensitive measure for monitoring the status of oral implant osseointegration when implant boundary conditions are good at the cortical level but still weak at the trabecular bone area.
The International journal of oral & maxillofacial implants 01/2014; 29(1):105-12. · 1.49 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Growth and differentiation factor-5 (GDF-5) is a multifunctional protein that regulates the development and repair in many tissues. The purpose of this study was to investigate whether GDF-5 may influence the proliferation, differentiation, and collagen turnover of human dental pulp cells.
Human dental pulp cells were treated with different concentrations of GDF-5 (0-500 ng/mL). Morphology of pulp cells was observed under a microscope. Cell proliferation was evaluated by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Immunofluorescent assay was used to observe the percentages of cell mitosis. Collagen content was measured by Sircol collagen assay. Tissue inhibitor of metalloproteinase-1 level in the culture medium was measured with enzyme-linked immunosorbent assay and Western blotting. Cell differentiation was evaluated by alkaline phosphatase (ALP) staining and ALP enzyme activity assay.
After exposure of dental pulp cells to various concentrations of GDF-5, cell number was up-regulated significantly in dose-dependent manner. GDF-5 also stimulated mitosis of dental pulp cells as indicated by an increased percentage of binucleated cells from 28% to 35%-45%. GDF-5 did not affect the collagen content and tissue inhibitor of metalloproteinase-1 level of pulp cells. GDF-5 decreased the ALP activity of pulp cells as analyzed by ALP staining and enzyme activity assay, with 14%-44% of inhibition.
GDF-5 revealed mitogenic and proliferative activity to dental pulp cells. GDF-5 showed inhibitory effect on ALP activity but little effect on the collagen turnover. These events are crucial in specific stages of dental pulp repair and regeneration. GDF-5 may be potentially used for tissue engineering of pulp-dentin complex.
Journal of endodontics 10/2013; 39(10):1272-7. · 2.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objective of this research is to study the e®ects of alumina addition on the microstructure-mechanical property relationship and sintering behavior of yttria (3 mol%)-stabilized zirconia (YSZ) ceramics. Well-dispersed YSZ/Al 2 O 3 ceramics containing 10À40 wt.% Al 2 O 3 were prepared by solid state reaction method. The relative density, average grain size, lattice parameters, microhardness, and fracture toughness of YSZ/Al 2 O 3 ceramics system sintered in the temper-ature range of 1250$1500 C as a function of Al 2 O 3 content were investigated. Experimental results showed that the ceramics with high Al 2 O 3 content and low sintering temperature tended to reveal low bulk densities. But the Al 2 O 3 content dependence on relative density for YSZ/Al 2 O 3 ceramics becomed deminishing when increasing the sintering temperature. Dense ceramics with composition of (80/20) (YSZ/Al 2 O 3) and sintered at temperature of 1400 C and 1450 C revealed the optimal Vickers hardness and fracture toughness properties. These ceramics with high Al 2 O 3 content tended to reveal small grain sizes. The high sintering temperature governs the slow grain growth and high hardness in materials indicating the good correlation between microstructure of fabricated dense and mechanical properties.
[Show abstract][Hide abstract] ABSTRACT: We previously demonstrated the autophagy-inducing activity in the crude extract of areca nut (ANE) and its 30-100 kDa fraction (ANE 30-100 K). This study aimed to analyze whether chronic ANE and ANE 30-100 K stimulations lead to higher stress resistance and autophagic activity in oral cells, and whether the resulting autophagic status in stimulated cells correlates with stress resistance.
Malignant cells from the mouth oral epidermoid carcinoma Meng-1 (OECM-1) and blood (Jurkat T) origins were stimulated with non-cytotoxic ANE and ANE 30-100 K for 3 months. Sensitivity to anticancer drugs of and autophagy status in stimulated cells, analyzed respectively by XTT assay and calculating microtubule-associated protein 1 light chain 3-II LC3-II/β-actin ratios from Western blot, were compared to non-treated cells. Autophagy inhibitors, 3-methyladenine (3-MA) and chloroquine (CQ), were used to assess whether autophagy inhibition interferes the altered chemoresistance.
Areca nut extract-stimulated (ANE-s) and ANE 30-100 K-stimulated (30-100 K-s) OECM-1 and Jurkat T cells generally exhibited higher cisplatin and 5-fluorouracil (5-FU) resistances, compared to non-stimulated cells. Most stimulated cells expressed significantly higher levels of LC3-II and Atg4B proteins. Interestingly, these cells also showed stronger tolerances against hypoxia environment and expressed higher LC3-II levels under glucose-deprived and hypoxia conditions. Finally, both 3-MA and CQ alleviated, albeit to different degrees, the increased chemoresistance in ANE-s and/or 30-100 K-s cells.
Chronic stimulations of ANE or ANE 30-100 K may increase tolerance of oral cancer and leukemia T cells to anticancer drugs, as well as to glucose deprivation and hypoxia conditions, and cause an elevation of autophagy activity responsible for increased drug resistance.
Journal of Oral Pathology and Medicine 06/2013; · 1.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 (R(2) = 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.
Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine 05/2013; · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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<0.001), respectively. The SMFs had no effect on erythrocyte morphology and metabolite levels. However, membrane fluidity of the samples exposed to 0.8-T SMF decreased significantly (p<0.05) in the hydrophobic regions. For the dehydration stability experiments, the samples exposed to 0.8-T SMF exhibited significantly lower (p<0.05) hemolysis. These results demonstrate that a 0.8-T SMF decreases membrane fluidity and enhances erythrocyte membrane stability to resist dehydration damage caused by slow cooling procedures.
PLoS ONE 03/2013; 8(3):e58988. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: KEYWORDS distal radial fracture; fracture fixation; PLA95 copolymer plate Abstract Background/purpose: Distal radius fractures are amongst the most common muscu-loskeletal bone injuries treated in emergency departments. The objective of this study was to evaluate the functional and radiologic outcomes of treating distal radius fractures with a re-sorbable volar polymeric implant system. Materials and methods: We applied the volar poly-5D/95L-lactide (PLA95) plate/screw system (Bonamates, BioTech One, New Taipei City, Taiwan) for intraosseous fixation after open reduc-tion of distally displaced radius fracture in four patients (three males and one female, ages range: 7e67 years). Another four patients [three females and one male, ages 68e70 (68.8 AE 1.0)] were treated with 3.5-mm metal volar T locking plates (Synthes, Paoli, PA, USA) as the control group. The minimum follow-up period was longer than 2.5 months for all cases. Results: At final functional and radiologic assessment, all of the distal radius fracture sites were united and one patient achieved excellent results, two patients had good results, and one had a fair result. All patient outcomes were satisfactory, and no major material-related infections or allergies were found. Conclusion: Within the limitations of this early clinical experiment, we conclude that the volar PLA95 copolymer plate/screw system can be used to treat distal radial fractures.
Journal of dental sciences 11/2012; 8:44-52. · 0.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: The aim of this study was to test whether or not a strong static magnetic field (SMF) had a positive effect on the survival rate of frozen erythrocytes. Materials and methods: Human erythrocytes were slow freezing at a rate of -1°C/min, to a final temperature of -20°C. During the freezing process, the cells were simultaneously exposed to an SMF with a magnetic induction of 0.2 or 0.4 T. After the cells were thawed, the survival rate, morphology, and function of the thawed erythrocytes were evaluated. Furthermore, tests of membrane fluidity were performed to assess the effect of the SMF on the cell membrane. Results: The slow freezing process coupled with an SMF increased the survival rate of frozen erythrocytes, without any negative effect on the cell morphology or function. The increases in relative survival rates of frozen erythrocytes were 5.7% and 9.1% when the cells were frozen in 0.2 T and 0.4 T groups, respectively. In addition, the 0.4 T group significantly increased the membrane rigidity of the erythrocytes. Conclusions: Slow freezing coupled with a strong SMF produced positive effects on the survival rate of thawed erythrocytes, without changing their normal function.
International Journal of Radiation Biology 08/2012; · 1.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to prepare resorbable α-calcium sulfate hemihydrate/amorphous calcium phosphate (α-CSH/ACP) bone substitute with a resorption period of 3–6 months specifically designed for dental implantation surgery. A one-pot process was used to manufacture α-CSH and ACP. Granular particles of α-CSH/ACP (60/40) with diameters of 420–840 μm were prepared. In dissolution test, both α-CSH/ACP (60/40) and CSD displayed rapid dissolution in the first 20 days, followed by a remarkably slow dissolution rate to reach weight retention plateaus of around 13.5% ± 0.7% and 40.5% ± 1.4% at 90 days, respectively. The in vivo study showed no adverse effects as a consequence of any of the implanted materials. After 3 weeks, the defects treated with α-CSH/ACP (60/40) showed more new bone formation (21.1%) than the empty control (13.6%) (p < 0.05). At 6 weeks, the treatment group with α-CSH/ACP (60/40) had more new bone formation (62.2%) than those with CSD alone (42.4%) and the empty control (40.1%) (p < 0.01). The complete in vivo resorption time within 3–6 months for α-CSH/ACP (60/40) was mathematically estimated by an extrapolation method. This biocompatible α-CSH/ACP (60/40) composite with a 3–6-month resorption period may be suitable for dental implantation surgery.
Materials Science and Engineering C 04/2012; 32(3):440–446. · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 100–500μm. The equilibrium swelling ratio, volume change, and antibacterial property were inversely proportional to the gel content. The PEC-2 scaffold composed of 8wt.% CS, and 2wt.% γ-PGA+2wt.% CMC had more-suitable gel properties (gel content of 55.3±1.1wt.% and volume change of 97.7±1.4v/v%) with inhibition zones of 14.4±0.3mm for Escherichia coli and 13.0±0.7mm 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.
Materials Science and Engineering C 03/2012; · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Magnetic cryopreservation has been successfully used for tooth banking with satisfactory implantation outcomes, suggesting that the method preserves human periodontal ligament cells and dental pulp stem cells (DPSCs). Therefore, magnetic cryopreservation may be applied for the preservation of DPSCs; however, this method has not been evaluated yet. A reliable cryopreservation method for live-cell preservation is important for the clinical applications of regenerative medicine. The conventional slow-freezing procedure with 10% dimethylsulfoxide (DMSO) may not be appropriate for stem cell-based therapies because DMSO is cytotoxic. The objective of this study was to investigate whether magnetic cryopreservation can be applied for DPSC cryopreservation. Cells isolated from human dental pulp were subjected to magnetic cryopreservation. Postthawing cell viability, adhesion, proliferation, expression of markers for mesenchymal stem cells (MSCs), differentiation ability of magnetically cryopreserved DPSCs and DNA stability were compared to those of cells subjected to the conventional slow-freezing method. The results indicated that a serum-free cryopreservation medium (SFM) containing 3% DMSO is optimal for magnetic cryopreservation. Post-thaw magnetically cryopreserved DPSCs express MSC markers, and perform osteogenesis and adipogenesis after induction similarly to fresh MSCs. No significant DNA damage was found in magnetically cryopreserved DPSCs. Magnetic cryopreservation is thus a reliable and effective method for storage of DPSCs. The smaller amount of DMSO required in SFM for cryopreservation is beneficial for the clinical applications of post-thaw cells in regenerative medicine.
[Show abstract][Hide abstract] ABSTRACT: The medical grade calcium sulfate is widely used in clinical applications for treating bone defects. A high-purity and predictable calcium sulfate (CS) synthesis process is desirable in the medical industry. The objective of this study was to develop a one-pot method for the direct preparation of calcium sulfate hemihydrates (CSHs; such as the α- and β-forms) in a CaCl2 solution. CS was synthesized by mixing K2SO4 and Ca(NO3)2·4H2O under various CaCl2(aq) concentrations and reaction temperatures under atmospheric pressure. The calcium sulfate dihydrate (CSD) was found to be an intermediate phase that converts to CSH during the synthesis process, and α-CSH was gradually transformed from β-CSH over time. Moreover, the kinetic of CSD conversion to CSH was strongly accelerated by increasing the CaCl2 concentration. As the reaction temperature was fixed in 90°C, the form of the CS reactant with an increase in the CaCl2 concentration was in the following sequence: CSD→CSD+β-CSH→CSD+β-CSH+α-CSH→α-CSH. In this study, the synthesis processing window of the CS reactant was established according the test results, and it is worth noting that all phases of CS hydrate could be synthesized with this system and well predicted by the constructed processing window.
Ceramics International 01/2012; · 2.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.