Application prospect of silicon nitride ceramics in dental implants / 口腔疾病防治

@#Silicon nitride has high fracture toughness and compressive strength similar to human bone. It meets the basic mechanical requirements of implants and has good biocompatibility. The micrometer/nanometer morphology surface characteristics of silicon nitride give it good osteogenic activity and antibacterial properties, which are helpful to reduce the incidence of periimplant inflammation. Therefore, silicon nitride has good application potential in dental implants. In orthopedics, silicon nitride implants have been used in spine repair and joint implantation. However, there is a lack of research on silicon nitride as dental implant material. The evaluation of the osteogenic and antibacterial properties of silicon nitride bioceramics prepared using different sintering additives and sintering processes, the antibacterial properties of silicon nitride on different dominant oral pathogens, and the osteogenic activity and antibacterial properties of silicon nitride materials implanted into the jaw need to be further studied. Combined with the latest research results at home and abroad, this review discusses the application potential of silicon nitride materials in dentistry.

Effect of calcium phosphate bone cement scaffolds loaded with emodin on osteogenic activity of osteoblasts / 中华创伤杂志

Objective:To explore the effect of calcium phosphate cement（CPC）scaffold loaded with emodin（EMO）on osteogenic activity of osteoblasts.Methods:The bone cement scaffold was prepared by mixing EMO powder and CPC powder（ratio 1∶9），adding citric acid and then was poured into polytetrafluoroethylene mold（EMO-CPC group）. A dose of 0.36 g CPC powder was mixed with citric acid and injected into the polytetrafluoroethylene mold（CPC group）. General morphology，setting time（initial setting time and final setting time），injection rate and compressive strength of stents were compared between the two groups. Primary osteoblasts were extracted and co-cultured with two sets of scaffolds. After co-culture for 3 days，their characterization was observed by scanning electron microscopy. Live/dead cell staining and 3-（4,5-dimethylthiazole-2）-2,5-diphenyltetrazolium bromide（MTT）colorimetric method were used to detect cell viability，toxicity and proliferation activity of scaffolds. Two sets of scaffolds were stained with immunofluorescence for osteopontin（OPN），and protein expression was observed under an inverted fluorescence microscope. After co-culture for 7 days，tetrazolium nitro blue/5-bromo-4-chloro- 3-indolyl-phosphate（NBT/BCIP）staining method was used for alkaline phosphatase（ALP）staining. After co-culture for 14 days，two sets of scaffolds were stained with Alizarin Red to detect their osteogenic activity.Results:Two sets of stents showed relatively smooth and flat topography under the scanning electron microscope. There were no significant differences in initial setting time，final setting time，injection rate and compressive strength of stents between two groups（ P > 0.05）. After co-culture for 3 days，the osteoblast clusters were adhered to the surface of the EMO-CPC scaffold，with good shape. Viable cell rate reached（98.2 ± 0.1）% in EMO-CPC group and（90.2% ± 0.1）% in CPC group（ P <0.05）. Cell proliferation activity in EMO-CPC group was stronger than that in CPC group（ P < 0.05）. OPN-specific staining showed that EMO-CPC group had stronger OPN protein fluorescence expression compared to CPC group. After co-culture for 7 days，expression of ALP in EMO-CPC group was higher than that in CPC group. After co-culture for 14 days，staining intensity of Alizarin Red in EMO-CPC group was more significant than that in CPC group. Conclusions:The EMO-CPC scaffold can provide a suitable environment for the growth of osteoblasts for it has better biocompatibility，cell proliferation and osteogenic activity than the CPC scaffold.

Effect of glycoside of short-horned epimedium Herb on the expressions of transforming growth factor β 1 and basic fibroblast growth factor induced membrane by Masquelet technology / 中国修复重建外科杂志

Objective: To observe the expressions of transforming growth factor β 1 (TGF-β 1) and basic fibroblast growth factor (bFGF) induced membrane by Masquelet technique in rats treated with glycoside of short-horned epimedium Herb, and to explore the effect of glycoside of short-horned epimedium Herb on Masquelet induced membrane. Methods: Sixty 3-month-old male Wistar rats were randomly divided into 3 groups with 20 rats in each group; a tibial bone defect (6 mm in length) model was established. The blank group (group A) was not treated; the control group (group B) and the experimental group (group C) were filled with vancomycin antibiotic bone cement in the drawing stage, and the bone cement was completely solidified. Group C was given perfused flavonoids glycoside of short-horned epimedium Herb (10 μmol/L) by gavage once a day (0.3 mL) from 1 day after operation, and groups A and B were given the same amount of normal saline by gavage. After operation, the recovery and wound healing of experimental animals were observed; at 4 weeks after operation, X-ray film was taken to observe the recovery of bone defect of proximal tibia; at 6 weeks after operation, the bone defect was observed, and the morphological changes and vascularization degree of granulation tissue and induction membrane tissue were observed; the expressions of TGF-β 1 and bFGF were observed by immunohistochemistry staining and ELISA detection. Results: The bone defect models of the 3 groups were established successfully, and there was no abnormality after operation. The incisions healed by first intention after operation. At 4 weeks after operation, X-ray films of proximal tibial defect showed that there was obvious space in group A, while bone cement was filled and Kirschner wire fixation was good in groups B and C. At 6 weeks after operation, the gross observation showed that the granulation tissue was filled in the defect area in group A; transparent membrane was formed in groups B and C, and microvessels were seen in some areas, and the microvessels in group C were significantly more than those in group B. Immunohistochemical staining showed that the expressions of TGF-β 1 and bFGF were negative in group A, but they were expressed in groups B and C, and the expressions of TGF-β 1 and bFGF in group B were significantly less than those in group C. ELISA detection showed that the expressions of TGF-β 1 and bFGF in group C were significantly higher than those in groups A and B ( P0.05). Conclusion: Glycoside of short-horned epimedium Herb can significantly increase the expressions of TGF-β 1 and bFGF, accelerate the process of osteogenesis, and contribute to bone shaping and reconstruction.

Osteogenic Activity of MSC Infected by Recombinant Adenovirus Vector Ad-LMP-1 / 中山大学学报(医学科学版)

[Objective]This study was designed to construct a recombinant adenovirus vector contains LMP-1 gene,and investigate the osteoinductive activity of MSC which were transfected recombinated adenoviral vector carrying LMP-1 gene.[Methods]Total RNA was extracted from mt osteoblast and the LMP-1 gene was acquired by RT-PCR,the LMP-1 gene and entry vector pENTR/D-TOPO were used to create the entry clone with the directional TOPO clone technology,then the entry clone and the expression vector were used to create the expression clone throush the LR recombination reaction.The adenovirus expression clone was linearized by PacI and transfected to the 293A cell line to harvest a high titer.Ad-LMP-1 was infected into the 3rd passage MSC,the expression of LMP-1 was detected by Western blot.The osteogenic activity of MSC was evaluated by the expression of collagen Ⅰ,ALP,osteocalcin and the formation of bone nodule.[Result]The LMP-1 gene was successfully acquired and confirmed,the entry clone and the expression clone were both verified by enzymes digestion,and the expression clone was further confirmed by sequenced.The expression of LMP-1 was detected successfully in MSC.The increasing expression of collagen Ⅰ,osteocalcin.ALP and bone nodule were observed by comparing to the control group.[Conclusion]Gateway technology not only make construction of the pAd-LMP-1 recombination adenovirus vector simple and fast,but also get a high transfection efficacy in MSC.LMP-1 gene can induce the osteoblast differention of MSCs,and improve its osteogenic activity.The adenovirus vector is reliable to be used in further gene therapy research.

Effect of dexamethasone concentrations on osteogenic activity of cultured human periosteal-derived cells

Nineteen Types of WNT Genes Mediate The Differentiation of C3H10T1/2 Cell Lines / 대한정형외과연구학회지

PURPOSE: In humans, nineteen types of WNT genes (WNTs) have been hightlighted up to date. The canonical Wnt cascade has recently emerged as a critical regulator of stem cells. To obtain new insights how nineteen WNTs affect mesenchymal stem cells differentiation, we analyzed the transcriptional activity, osteogenic and adipogenic activity of WNTs in mesenchymal stem cells. MATERIALS AND METHODS: Recombinant adenoviruses expressing nineteen WNTs were constructed to infect pluripotent mesenchymal progenitor C3H10T1/2 cells. Transcriptional activity was determined by using the luciferase reporter assay. Osteogenic activity was determined by measuring the induction of alkaline phosphatase upon Wnt stimulation. Adipogenic activity was measured by histochemical Oil red-O staining. RESULTS: WNT1, 2, 3, 3A and 10B significantly induced transcriptional activity in C3H10T1/2 cells. WNT1, 2, 3, 3A and 10B significantly induced alkaline phosphatase activity, but inhibited adipogenic activity in C3H10T1/2 cells. The results of qualitative and quantitative assay of alkaline phosphatase activity were consistent with those of luciferase assay for transcriptional activity and Oil red-O staining for adipogenic activity. CONCLUSION: We could expect that WNT1, 2, 3, 3A and 10B may play a crucial role in inducing osteoblast differentiation of mesenchymal stem cells.

In vitro and In vivo Osteogenic Induction of Mesenchymal Stem Cells from Rabbit Bone Marrow / 대한정형외과연구학회지

PURPOSE: The aim of this study was to analyze the osteogenic effect of cultured rabbit mesenchymal stem cells(MSCs). MATERIALS AND METHODS: MSCs were obtained from rabbit femur and were cultured in a Dulbecco's Modified Eagle's Medium(DMEM) with beta-glycerophosphatate, L-ascorbic acid, and dexamethasone to proliferate and differentiate into osteoprogenitor cells until 12 weeks. The expression of osteogenic markers was detected by reverse transcription-polymerase chain reaction(RT-PCR) and the release of osteocalcin was measured by Enzyme-linked Immunosorbent Assay(ELISA). MSCs that were cultured on the porous poly-L-lactic-co-glycolic acid(PLGA) scaffold were implanted into athymic nude mouse to observe the osteogenic activity. RESULTS: As the time, we observed osteoblastic-like cells on the culture flask. Mineralized nodules were observed at 3-4 weeks. Osteogenic markers such as osteopontin, osteonectin, type I collagen, and alkaline phophatase were all identified at 2 weeks. But, expression of osteocalcin was only detected after cells differentiation. The amount of osteocalcin which is a specific protein in osteoblast, increased gradually from 2 weeks until 7 weeks. Scanning electron microscopy revealed that the MSCs were well adhered and proliferated within the PLGA scaffold. Immature bone was identified after 10 weeks in the histological examination of transplanted cell-scaffold composit. CONCLUSION: Our results demonstrate gradual differentiation of MSCs into osteoblastic cells. The adhesion and proliferation of the cells within the biodegradable scaffold represents the possibility of bone formation using cell-scaffold composites.