[Development of human embryonic stem cell platforms for human health-safety evaluation].

The human embryonic stem cells (hESCs) serve as a self-renewable, genetically-healthy, pluripotent and single source of all body cells, tissues and organs. Therefore, it is considered as the good standard for all human stem cells by US, Europe and international authorities. In this study, the standard and healthy human mesenchymal progenitors, ligament tissues, cardiomyocytes, keratinocytes, primary neurons, fibroblasts, and salivary serous cells were differentiated from hESCs. The human cellular health-safety of NaF, retinoic acid, 5-fluorouracil, dexamethasone, penicillin G, adriamycin, lead acetate PbAc, bisphenol A-biglycidyl methacrylate (Bis-GMA) were evaluated selectively on the standardized platforms of hESCs, hESCs-derived cardiomyocytes, keratinocytes, primary neurons, and fibroblasts. The evaluations were compared with those on the currently most adopted cellular platforms. Particularly, the sensitivity difference of PM2.5 toxicity on standardized and healthy hESCs derived fibroblasts, currently adopted immortalized human bronchial epithelial cells Beas-2B and human umbilical vein endothelial cells (HUVECs) were evaluated. The RESULTS showed that the standardized hESCs cellular platforms provided more sensitivity and accuracy for human cellular health-safety evaluation.

[Three-dimensional measurement and facial symmetry analysis for the craniofacial structure of people in North China with normal occlusion].

OBJECTIVE: To investigate the internal regularities and symmetry of craniofacial structures from adults with normal occlusion in North China. METHODS: The study consisted of 60 volunteers who were examined with spiral 3D computed tomography (CT). The axial images of craniofacial structure were reconstructed into 3D models and analyzed by using Proplan 1.2 software to measure the internal regularities and symmetry of craniofacial structures. RESULTS: All the linear measurement's value of the males were bigger than those of the females (P<0.05). There were no significant differences in the ratio measurements between the males and the females(P>0.05). Facial asymmetry was less than 10% in all the images. CONCLUSION: CT is an effective method for three-dimensional analyses of craniofacial structure and symmetry. There are certain and harmonious regularities in normal 3D craniofacial structures. The 3D craniofacial structure database of people with normal occlusion can provide standards and references for diagnosis and treatment planning of craniofacial deformities.

[Three-dimensional imaging for quantitative evaluation of facial profile of edentulous patients before and after complete dentures restoration].

OBJECTIVE: To collect and analyze the Three-dimensional (3D) facial profile variation of edentulous patients restored by complete denture. METHODS: The 3D facial images of 20 Atwood Class II edentulous patients were taken by DSC-2 3D facial imaging system before and after restoration of complete denture. Then, the two 3D facial images of each patient before and after restoration were registered in the same coordinate system by partial structure overlap. The differences between these two 3D facial images were statistically analyzed. RESULTS: The major facial profile variation of Atwood Class II edentulous patients restored by complete denture focused in the area around the upper lip and the corner of the mouth. The change of lower lip and chin area was not obvious. The shift in the sagittal direction was significantly more evident than that in the vertical direction, while the shift in the horizontal direction was the least one. CONCLUSION: The pattern of facial profile variation of edentulous patients restored by complete denture based on 3D imaging may provide reliable data support for prediction and communication in clinical practice.

[Effects of isoquercitrin from Craibiodendron yunnanense on osteogenic differentiation of MC3T3-E1 cells].

Natural products especially flavonoids are being explored for their therapeutic potentials in reducing bone loss and maintaining bone health. The present study is to investigate the effects of isoquercitrin from Craibiodendron yunnanense with different concentrations at 1 x 10(-4), 1 x 10(-5), 1 x 10(-6), 1 x 10(-7) mol x L(-1) on proliferation, differentiation and mineralization of MC3T3-E1. Cell proliferation was assessed by CCK-8 kit at 1, 3, 5 and 7 days of culture. Alkaline phosphatase (ALP) activity were performed qualitatively and quantitatively on day 7, and alizarin red S staining was employed to access the mineralization of cells on day 21. The osteogenic markers ALP, collagen type I (COL 1A1), runt-related transcription factor 2 (Runx-2) and Osterix were detected to analysis early osteogenic differentiation of cells on day 3 by RT-PCR. The results showed that isoquercitrin had a dose-dependent effect on the proliferation, osteogenic differentiation, mineralization and gene expression of MC3T3-E1 in the range from 1 x 10(-7) to 1 x 10(-5) mol x L(-1). At concentrations above 1 x 10(-4) mol x L(-1) isoquercitrin showed cytotoxicity, while 1 x 10(-6) mol x L(-1) is the optimal concentration of isoquercitrin to improve the osteoblastic activity. All these results implied that isoquercitrin might be the major composition of traditional Chinese medicine C. yunnanense to treat bone fractures.

[Development of human embryonic stem cell model for toxicity evaluation].

The current international standard for toxicity screening of biomedical devices and materials recommend the use of immortalized cell lines because of their homogeneous morphologies and infinite proliferation which provide good reproducibility for in vitro cytotoxicity screening. However, most of the widely used immortalized cell lines are derived from animals and may not be representative of normal human cell behavior in vivo, in particular in terms of the cytotoxic and genotoxic response. Therefore, It is vital to develop a model for toxicity evaluation. In our studies, two Chinese human embryonic stem cell (hESC) lines as toxicity model were established. hESC derived tissue/organ cell model for tissue/organ specific toxicity evaluation were developed. The efficiency and accuracy of using hESC model for cytoxicity, embryotoxicity and genotoxicity evaluation were confirmed. The results indicated that hESCs might be good tools for toxicity testing and biosafety evaluation in vitro.

Two new grayanane diterpenoids from the flowers of Rhododendron molle.

A phytochemical investigation of the flowers of Rhododendron molle has yielded two new grayanane diterpenoids, rhodomolleins F and G (1, 2). Compounds 1 and 2 possessed an oxo-bridge between C-5 and C-9, and their structures were elucidated on the basis of interpretation of spectroscopic data, including 1D and 2D NMR techniques.

[Functional maxillary reconstruction with free composite fibula flap].

Maxillary defects resulting from tumor resection or trauma can cause severe functional and cosmetic deformities. Maxillary reconstruction has long been a challenge for oral maxillofacial surgeons. Functional maxillary reconstruction with vascularized composite bone flap and osseointegrated implants is one of the most important improvements in head and neck reconstructive surgery. Since 1999, our research group has performed a comprehensive research on functional maxillary reconstruction with free composite fibula flap. Clinical data of the patients with maxillary reconstruction using free fibula flap were analyzed to describe the indications and principles of perioperative period of this technique. The modified free fibula flexor-hallucis longus myofascial flap was introduced, which could overcome the disadvantages of traditional free composite fibula flap. The donor site morbidity, post-operative speech outcome, mastication function, and quality of life were evaluated objectively. The biomechanical effects of stress distribution on maxilla reconstructed by free fibula composite flap were analyzed by three-dimensional finite element analysis. These studies demonstrated maxillary defects can be reconstructed successfully using free fibula flaps. This procedure also allows dental implant or conventional denture rehabilitation, which can improve the patient's appearance and oral function and enhance the overall quality of life. The fibula free flap transfer has a high success rate and low perioperative complication rate, making it an ideal choice for maxillary defect reconstruction.

Effects of Preoperative Anxiety Status on Haemodynamic Changes during and after Tooth Extraction in Middle-aged and Elderly Patients with Hypertension: a Prospective Repeated-Measures Cohort Study.

OBJECTIVE: To investigate the effects of dental anxiety on fluctuations in blood pressure (BP) and heart rate (HR) during tooth extraction in hypertensive patients under local anaesthesia, and how they are influenced by various confounding variables. METHODS: This is a prospective repeated-measures cohort study involving 600 patients successively recruited from Peking University School and Hospital of Stomatology, Beijing, China. BP and HR were repeatedly measured at rest (T0), before anaesthesia (T1), during tooth extraction (T2) and after tooth extraction (T3). Anxiety status was measured prior to local anaesthesia using a modified dental anxiety scale (MDAS). Three groups were assigned: mild anxiety (Corah DAS score of 4 to 8), moderate anxiety (score of 9 to 12) and severe anxiety (score of 13 to 20). We used a generalised linear mixed model (GLMM) to analyse the effects of dental anxiety on fluctuations in BP and HR. Interaction analysis was used to further explore the correlationship between these interactive factors. RESULTS: The mean anxiety scale score was 9.63 ± 2.88. Severe preoperative anxiety (score of 14 to 20) was associated with significantly increased HR during administration of anaesthesia. Patients with severe anxiety also displayed a significantly greater increase in HR during anaesthetic administration (P < 0.001). When analysing the joint effects of different anxiety statuses over time, blood pressure was significantly elevated in all patients with moderate and severe anxiety during tooth extraction at T2 (ß = 1.25, 95% CI 0.24 to 2.27). We also observed a significant decrease in HR in the moderate anxiety group at T3 (ß = -1.51, 95% CI -2.38 to -0.63) and a significant increase in HR in the severe anxiety group at T1, T2 and T3 (ß = 2.52, 95% CI 1.12 to 3.93; ß = 3.84, 95% CI 2.30 to 5.38; ß = 4.57, 95% CI 3.03 to 6.11, respectively). CONCLUSION: This study indicates that the effects of dental anxiety on BP and HR in middle-aged and elderly patients with hypertension during local anaesthesia and tooth extraction were influenced by various confounding variables.

Use of a CAD/CAM-fabricated glass fiber post and core to restore fractured anterior teeth: A clinical report.

Prefabricated glass fiber posts are widely used; however, their shape cannot be changed and they can be unsuitable for severely damaged teeth with wide root canals. This clinical report describes a procedure for restoring a severely damaged anterior tooth with a customized 1-piece glass fiber post and core, fabricated using a CAD/CAM system. This 1-piece glass fiber post and core adapts better to the root canal than a prefabricated glass fiber post, and reduces the cement layer thickness. Furthermore, it does not require the use of a composite resin foundation.

Developments in Antibacterial Therapy: Focus on Physical Stimuli Approaches.

At present, various antibacterial therapeutic modalities are available in the clinic. However, due to the rampant abuse of antibiotics over the past few decades and the consequent emergence of innumerable drug-resistant strains of bacteria, it is imperative to develop new and effective antibacterial therapeutic strategies. In recent years, the physical stimuli-based approach to antibacterial therapy has aroused much interest as an alternative to antibiotics and has become a major focus of antibacterial research. In this review, the application of different physical stimuli, including electricity, magnetism, light, ultrasound and thermal stimulation, in antibacterial research is critically examined in order to provide new ideas and directions for the further development of antibacterial therapy in clinical dentistry.

Efficacy of a mineralized collagen bone-grafting material for peri-implant bone defect reconstruction in mini pigs.

The mechanism of the mineralization process induced by natural mineralized collagen (MC) has been investigated for decades. The purpose of this study was to investigate the efficacy of self-assembled MC for peri-implant bone defect reconstruction in a mini pig. A standardized peri-implant bone defect model was created using 14 mini pig mandibles. Two materials were evaluated, i.e. a mixture of hydroxyapatite and collagen (Type A, TA), and self-assembled MC (Type B, TB). Bio-Oss (BO) and untreated (blank control, BC) groups were used as controls. After 3- and 6-month healing periods, the mini pigs were sacrificed for histomorphometric and microcomputed tomography analysis. After 3 months of healing, the average alveolar ridge height was 3.27 ± 1.57 mm for group TA, 3.28 ± 2.02 mm for group TB and 3.37 ± 1.09 mm for group BO, while group BC showed the lowest height of 2.68 ± 0.47 mm. After 6 months of healing, the average alveolar ridge height was 2.64 ± 1.13 mm for group TA, 4.31 ± 1.80 mm for group TB and 3.87 ± 1.38 mm for group BO, while group BC showed the lowest height of 2.48 ± 1.80 mm. The experimental groups and control group showed similar bone volume density, bone complexity and histological reaction. The self-assembled MC (Type B) stimulated new bone formation in the reconstruction of deficient alveolar ridges around the dental implant; it also displayed excellent clinical operability compared with bone grafts without collagen.

Pulmonary delivery of scutellarin solution and mucoadhesive particles in rats.

The objectives of this study were to investigate the effects of mucoadhesive excipients on systemic bioavailability of an inhaled drug and to evaluate the feasibility of using the pulmonary route for non-invasive systemic delivery of scutellarin, a poorly orally absorbed flavonoid glucuronide. Following intratracheal spray of the scutellarin solution, the bioavailability was found to be approximately 77% in rats, which was >30-fold higher than that via the peroral route. In addition, the pulmonary absorption of scutellarin appeared to avoid the intestinal first-pass metabolism accompanied by peroral administration. Spray-dried scutellarin particles with the presence of mucoadhesive excipients were found to affect the corresponding mucociliary transport rate (MTR) as evaluated by a frog palate model. The pharmacokinetic results indicated that the magnitude of AUC(0-480) of intrapulmonary delivered drug particles was not correlated to the fine particle fraction (FPF) but inversely related to the MTR. Incorporating mucoadhesive polymeric mixtures into the scutellarin particles, the MTR decreased by sixfold, and the absolute bioavailability of the drug was found to increase from 70.1% to 97.9% despite a decrease in the FPF. Moreover, in vitro results evaluated using Calu-3 and A549 cell lines showed that scutellarin and spray-dried particles with or without the presence of mucoadhesives exhibited no local cell cytotoxic effects in the tested concentration range. In conclusion, the conducting airway is well permeable to scutellarin, and scutellarin may be effectively delivered systemically through inhalation of respirable droplets or particles.

Directing osteogenic differentiation of BMSCs by cell-secreted decellularized extracellular matrixes from different cell types.

Cell-secreted decellularized extracellular matrixes (D-ECM) are promising for conferring bioactivity and directing cell fate to facilitate tissue regeneration. A cell sheet is a good shape for obtaining D-ECM after decellularization. In this study, cell sheets derived from bone marrow mesenchymal stem cells (BMSCs), MC3T3 osteoblasts, and L929 fibroblasts were decellularized, the three types of D-ECMs obtained were investigated for their capabilities in inducing osteogenic differentiation of re-seeded BMSCs. The D-ECMs were found to be rich in collagen and glycosaminoglycan, at the same time, showing the presence of growth factors, such as vascular endothelial growth factor and bone morphogenetic protein. These all supported the proliferation of BMSCs well, however, they influenced the osteogenic differentiation of BMSCs to different extents. The D-ECM prepared from the BMSC sheet was found to promote the osteogenic differentiation of re-seeded BMSCs the most in vitro, as well as displaying the potential to induce ectopic osteogenesis when being subcutaneously implanted. The results suggested that D-ECMs would be promising for bone tissue engineering applications, however, they favored osteogenesis to different extents, which was closely related to the cell types.

[Construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds and dog periodontal ligament cells].

OBJECTIVE: To investigate the construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds (beta-TCP/col) and dog periodontal ligament cells (PDLCs). METHODS: Dog PDLCs were isolated, cultured and identified. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of beta-TCP/col on the proliferation of PDLCs. The cells were seeded onto porous beta-TCP/col scaffolds. The cellular capability of adhesion and growth on porous beta-TCP/col surface was investigated visually by scanning electron microscopy (SEM). RESULTS: The cytotoxicity assay indicated that there was no significant difference between beta-TCP/col and the control during the 7 days (P>0.05). SEM showed cells successfully adhered to porous beta-TCP/col scaffolds and spread extensively. Matrix secretions were found on the cell surface. CONCLUSION: Porous beta-tricalcium phosphate/collagen scaffolds were of good biocompatibility to the dog periodontal ligament cells, and were potential ideal candidates for periodontal tissue engineering.

Mechanical performance of polymer-infiltrated zirconia ceramics.

OBJECTIVE: The aim of this study was to evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of pre-sintering temperature (1000-1150°C). METHODS: Polymer-infiltrated zirconia ceramics were prepared by combining the porous zirconia networks and polymer through infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism were observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. A nanoindentation system was employed to determine elastic modulus and hardness. RESULTS: Different porosities and polymer contents can be obtained by tuning the pre-sintered temperature of zirconia ceramic precursors. Zirconia network porosity varies from 46.3% to 34.7% and the relevant polymer content ranges from 18.4wt.% to 12.3wt.% when the pre-sintered temperature is set from 1000°C to 1150°C. The flexural strength, fracture toughness, hardness, and elastic modulus values of the specimen pre-sintered at 1150°C are 240.9MPa, 3.69MPam1/2, 3.1GPa, and 58.8GPa, respectively. CONCLUSION: The pre-sintering temperature has a significant effect on the microstructure and mechanical properties of polymer-infiltrated zirconia ceramics and the optimal pre-sintering temperature is 1150°C. CLINICAL SIGNIFICANCE: Specimen pre-sintered at 1150°C shows tooth-like mechanical properties, suggesting a promising restorative material in dental clinic. Moreover, the synthesis process is simple and can be easily performed in a prosthesis laboratory.

[Preparation of chicken egg yolk antibody against Candida albicans and effect of temperature on its titer].

OBJECTIVE: To prepare chicken egg yolk antibody (IgY) against Candida albicans and to study its biological properties in the interest of its further application. METHODS: Ten 25 weeks old laying hens were immunized with Candida albicans. IgY was isolated from the yolks of eggs by the water dilution (WD) method. Its yield, purity, and molecular weight were measured by Bradford method and Tris-tricine gel electrophoresis, respectively. The antigenicity of IgY was determined with Western blot method. The specific combination of IgY and Candida albicans was assayed with immunohistochemistry method. The activity of IgY was evaluated by enzyme-linked immunosorbent assay (ELISA). RESULTS: The yield and purity of IgY were 7.9 g/L and 91.5%, respectively. It had the same molecular weight and antigenicity in comparison with IgY of chicken serum and normal chicken IgY. It could specifically combine with Candida albicans. Its titer was 1:12,000. CONCLUSION: The production and purity of IgY were high. Its titer was good and did not decrease under a body temperature condition after 48 h. The IgY antibody had a combination capacity of specificity for Candida albicans in vitro.

[Cloning and sequencing of the GTP cyclohydrolase I function region of azole target enzyme gene in artificially induced resistant Candida albicans].

OBJECTIVE: To study the relationship between gene mutation of GTP cyclohydrolase I function region in lanosterine 14 alpha-demethylase (14-DM) DNA sequence and drug resistance of Candida albicans. METHODS: One standard strain and 2 isolate strains of Candida albicans were induced artificially by fluconazole plus albendazole. The gene fragments of the 3 strains and another 2 clinical isolates which were resistant to fluconazol were detected by PCR, and then cloned onto pMD-18T vectors to sequence and analyze the change of gene sequence after the induction. RESULTS: The sequences underwent substantial gene mutations after induction. Some of the mutations resulted in alteration of amino acids. The sequence change and subsequent alteration of amino acids in the tested strains coincided with those in the clinical isolates. CONCLUSION: Gene mutation and alteration of amino acid of 14-DM GTP domain are related to azole-resistance in Candida albicans.

High strength and toughness in chromatic polymer-infiltrated zirconia ceramics.

OBJECTIVE: To evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of Fe2O3 concentration (0-0.3mol%). METHODS: Polymer-infiltrated zirconia ceramics with different concentrations of Fe2O3 were prepared by infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism was observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. Data were analyzed by Weibull distribution. A nanoindentation system was employed to determine elastic modulus and hardness. RESULTS: With increasing content of Fe2O3, the flexural strength, fracture toughness, elastic modulus and hardness are all greatly enhanced and the chromatic behavior also improves significantly. As a tradeoff made between strength and elastic modulus, specimen containing 0.2mol% Fe2O3 is found to be the better one, with flexural strength and fracture toughness values being 336.8MPa and 3.91MPam1/2, respectively. Moreover, it maintains a relatively low elastic modulus of 88.2GPa and a moderate hardness of 4.8GPa, close to those of natural enamel. SIGNIFICANCE: This polymer-infiltrated zirconia ceramic material is a dental material of biomimetic chromatic and mechanical properties.

[The effect of simulate intraoral sandblasting on the band strength between enamel and composite resin].

OBJECTIVE: To study whether the bond strength between enamel and composite resin could be enhanced by intraoral sand abrasive. METHODS: Ten human maxillary first incisior teeth were divided into 2 groups The experimental group was sandblasted with 30 microm Al2O3 (CoJet-Sand, pressure 300 kPa) from a distance of 5 mm for 5 seconds, and the control group were not sandblasted. The Herculite composite resin composite cylinders were bonded with Coltene system. Bonded specimens were stored in 37 degrees C distilled water for 24 h, then were subjected to shear force in a testing machine. Stress at failure was calculated in Mpa, and mode of failure was recorded. The Student t test was applied to the data. RESULTS: The shear bond strength of experimental groups was (33.0+/-1.8) MPa, and that of control groups was (26.7+/-5.2) MPa,there was significant difference between these two groups. All the adhesive failures happened at the enamel composite resin interface, except that cohesive failure happened in one sandblasted specimen. CONCLUSION: Intraoral sandblasting could significantly enhance the shear bond strength between enamel and composite resin.