Effect of chlorine dioxide and sodium hypochlorite on the dissolution of human pulp tissue – An in vitro study

Background

Organic tissue dissolution is an important property of an irrigant which aids in the success of root canal treatment. Recent studies have advocated the use of Chlorine dioxide as an endodontic irrigant. The aim of this study is to compare the dissolution efficacy of chlorine dioxide and sodium hypochlorite on human pulp tissue.

Methods

In this study, 2% Sodium hypochlorite, 5% Chlorine dioxide and isotonic saline solution (control) were used. Thirty human pulp tissue specimens were exposed to three test solutions (n = 10) for 30 min following which the loss of weight was compared from the original weight by using a digital analytical balance.

Results

Sodium hypochlorite was more efficient in dissolving human pulp tissue when compared to Chlorine dioxide. Isotonic saline solution failed to dissolve any of the specimens.

Conclusion

5% Chlorine dioxide is capable of dissolving human pulp tissue but sodium hypochlorite was more effective.     

Effect of chlorine dioxide and sodium hypochlorite on the dissolution of human pulp tissue – An in vitro study

Background

Organic tissue dissolution is an important property of an irrigant which aids in the success of root canal treatment. Recent studies have advocated the use of Chlorine dioxide as an endodontic irrigant. The aim of this study is to compare the dissolution efficacy of chlorine dioxide and sodium hypochlorite on human pulp tissue.

Methods

In this study, 2% Sodium hypochlorite, 5% Chlorine dioxide and isotonic saline solution (control) were used. Thirty human pulp tissue specimens were exposed to three test solutions (n = 10) for 30 min following which the loss of weight was compared from the original weight by using a digital analytical balance.

Results

Sodium hypochlorite was more efficient in dissolving human pulp tissue when compared to Chlorine dioxide. Isotonic saline solution failed to dissolve any of the specimens.

Conclusion

5% Chlorine dioxide is capable of dissolving human pulp tissue but sodium hypochlorite was more effective.     

Role of transforming growth factor P and bone morphogenetic protein composite on repair of bone defects

Bonerepairisacomplicatedprocess.Recentstudiesdemonstratedthatseveralgrowthfactorsplayanimportantroleinboneformation.Bonemorphogeneticproteins(BMPs)induceboneformationthroughstimulatingundifferentlatedmesenchymalproliferationanddifferentiationandinitiatingheterotopicboneformation.Transforminggrowthfactor5(TGF--0),mostabundantinquantityofthegrowthfactorsinthebody,stronglypromotestheembryogenesis,traumahealing,matrixsynthesis,osteoandosteochondralformationandboneremodeling.Ourpreviousexperimen…     

Evaluation of transforming growth factor β and bone morphogenetic protein composite on healing of bone defects

ＥｖａｌｕａｔｉｏｎｏｆｔｒａｎｓｆｏｒｍｉｎｇｇｒｏｗｔｈｆａｃｔｏｒβａｎｄｂｏｎｅｍｏｒｐｈｏｇｅｎｅｔｉｃｐｒｏｔｅｉｎｃｏｍｐｏｓｉｔｅｏｎｈｅａｌｉｎｇｏｆｂｏｎｅｄｅｆｅｃｔｓＳｕｎＹｕｐｅｎｇ孙玉鹏，ＺｈａｎｇＷａｎｑｉｎｇ张皖清，Ｍ...     

Potential bone-inducing activity in vitro of recombinant human bone morphogenetic protein-7 from a CHO expression system

Objective: To express the recombinant human bone morphogenetic protein-7 (rhBMP-7) in Chinese hamster ovary(CHO) cells, and to establish the in vitro biological activity assay of rhBMP-7.Methods: Human BMP-7 cDNA was subcloned into pl14 mammalian expression vector and transfected to CHO cells by using the Lipofectamine^2000 transfection method. CHO cell supernatants were harvested and analyzed to identify the molecule mass of secreted rhBMP-7 and examine its biological activity in vitro to stimulate the synthesis of alkaline phophatase(ALP), a characteristic of osteoblast phenotypes. Results:rhBMP-7 was produced stably in CHO cells, as a processed mature disulfide-linked homodimer, with an apparent molecular mass of 36 000. Examination of the rhBMP-7 biological activity showed that rhBMP-7 specifically stimulated the production of ALP(4-fold increase at 100 ng of rhBMP-7/ml). Conclusion: The rhBMP-7 from CHO expression system has significant biological activity in induction of osteoblast phenotype, which demonstrates rhBMP-7 has the potential bone regeneration activity.     

Evaluation of transforming growth factor beta and bone morphogenetic protein composite on healing of bone defects.

OBJECTIVE To evaluate the effect of transforming growth factor-beta/bone morphogenetic protein (TGF-beta/BMP) composite on the healing of large segmental bone defects and to discuss the interaction between TGF-beta and BMP during bone repair.

METHODS A 1.5 cm segmental defect was made in the mid-upper part of the radial shaft of 48 adult rabbits. The defects were filled with implants of TGF-beta/carrier, BMP/carrier or TGF-beta/BMP/carrier separately. 120 micrograms of purified bovine TGF-beta and 12 mg of BMP were used in the composite. The defects were examined radiographically and histologically at 4, 8, 12 and 16 weeks post-operation.

RESULTS In the group filled with TGF-beta/BMP composite, the defect areas were bridged at 4 weeks, with callus of uniform radiodensity. Cortices of the cut ends were obscured by new bone. By 16 weeks post-operation, the defects were bridged by uniform new bone and the cut ends of the cortex could not be seen in all groups. In group of BMP/carrier, the defects were filled with more irregular woven bone callus than in other two groups. TGF-beta/BMP implanted defects in animals killed at 16 weeks showed histologically new lamella and woven bone that was formed in continuity with the cut ends of the cortex. Medullar canal was recanalized and contained marrow elements with normal appearance.

CONCLUSIONS These data demonstrate not only the synergistic action between TGF-beta and BMP in the process of bone healing, but also a better effect of TGF-beta/BMP composite than single TGF-beta or BMP on bone repair, especially in the early stage of bone repair process.

     

Effects of bone morphogenetic protein on the osseointegration of porous-surfaced implants：An experimental study in rabbits

Objective： Research on enhancing early osseointegration of cementless implants to improve early fixation and reducing of risk of loosening. Methods ： Thirty New Zealand rabbits were divided into two groups at random. BMP combined with DBM 30 mg was inserted around the prosthesis in 15 rabbits as experimental group, the remaining rabbits were served as control group. After 4, 8, and 12 weeks, five rabbits were sacrificed in each group. The humerus with the implants were retrieved. Bone ingrowth was analyzed by none-decalcification bone ground section and biomechanical test. Results： At the end of 4 and 8 weeks the osseointegration rates of BMP group were higher than those of control （P 〈 0.05）. The ultimate shear strength between BMP treated implantation and the control was the same as the results in osseointegration rates at 4, 8 weeks （P 〈 0.05）. However, there was no difference between the treated and untreated group in the osseointegration rate and ultimate shear strength at 12 weeks （P 〉 0.05）. Conclusion： BMP combination can enhance bone growth into gaps around cementless implants, especially in the early postoperative period.     

Expression of mature peptide of human bone morphogenetic protein-2 in Escherichia coli

bonemorphogenetlcprotein-:antI--/eisiveroleduringboneregenerationandrepairaswellasduringvariousstagesofelnbryonaldevelopment['].ThelengthofthecompletecDNAofhumanhonemorphogeneticprotein-2(hBMP-2)is1587hp,whose1188hpopenreadingframeencodesa396aminoacidsproteinwhichconsistsofasignalpeptide,apro--Peptideanda114ahanoacidmaturePeptide.FunctionalhBMP-2waseverexpressedinCOS,CHOandinsectcells,hutnotinE.colt:'.liuXinping['.",InZifan[5',ZhaoMing='jandlinbangetal-':haveexpressedvariedC-tenonalP…     

骨形成蛋白体外对培养的人牙髓组织的诱导作用

骨形成蛋白可促进牙髓细胞增殖的诱发修复性牙本质形成，作应用体外组织培养技术，分别通过光镜和透射电镜观察了牛骨形成蛋白对体外培养的人牙髓组织的诱导作用，结果发现，培养３ｄ后可见增殖的星形细胞，其胞浆少，细胞小器不发达，培养７ｄ后，可见透明基质中埋有一些软骨样细胞，该细胞胞浆丰富，细胞小器发达，并含有丰富的分泌小泡，说明骨形成蛋白可促进牙髓细胞从低分化状态向高分化状态分化。     

BMP2在大鼠牙髓损伤修复中的表达及其对牙髓细胞的生物学效应

目的：从体内体外两方面探讨BMP2在牙髓损伤修复，尤其是牙髓细胞分化过程中的作用。方法：建立大鼠牙髓损伤修复模型和体外人牙髓细胞连续培养，采用免疫组织化学、MTT法和酶动力学等方法，检测BMP2在体内牙髓组织损伤修复过程中的表达，并比较不同浓度rhBMP2对体外人牙髓细胞连续培养各阶段细胞增殖活性及ALP活性的影响。结果：体内牙髓组织损伤修复过程中存在BMP2的表达，牙髓组织损伤修复的不同阶段其表达部位和强度发生变化；rhBMP2可提高体外培养人牙髓细胞的增殖活性，与其本身浓度有关，并可促进人虎髓细胞ALP活性，呈浓度依赖性；结论：BMP2是参与牙髓损伤修复，尤其是牙髓细胞的增殖和分化的重要因子之一。     

rhBMP2对人牙髓干细胞分化及Delta蛋白表达的影响

目的：研究重组人骨形成蛋白2（rhBMP₂）对人牙髓干细胞分化及Delta蛋白表达的影响,为人牙髓干细胞的研究提供理论依据。方法：酶消化法获得人牙髓干细胞,光镜下进行形态学观察,免疫荧光法检测细胞表面标志的表达;取第5代牙髓干细胞, 分为实验组（加含50 μg•L^-1rhBMP₂的培养液）及阴性对照组（只加入培养液）,检测碱性磷酸酶活性和Delta蛋白表达的变化。结果：人牙髓干细胞呈集落状生长, 免疫组织化学检测显示nestin、 vimentin染色呈阳性,免疫荧光法检测STRO-1呈阳性。与阴性对照组比较,实验组第7、14及21天碱性磷酸酶活性均明显升高（P<0.01）,第21天Western blotting法检测Delta蛋白表达明显升高(P<0.05)。 结论：培养的牙髓干细胞具有干细胞特性,并且rhBMP₂可使其碱性磷酸酶活性增高并上调Delta蛋白表达,提示Delta蛋白可能参与牙髓干细胞向成牙本质样细胞分化的过程。     

体外培养人牙髓细胞的初步实验观察

目的 经过人牙髓细胞的培养,获得足够量的传代细胞,为进一步的实验提供基础;观察人牙髓细胞的形态、结构。方法 组织块法、酶消化法联合应用体外培养人牙髓细胞;应用倒置相差显微镜、透射电镜观察人牙髓细胞的形态与结构。结果 体外培养人牙髓细胞成功率低;人牙髓细胞呈成纤维细胞形。结论 培养的人牙髓细胞维持了体内牙髓细胞的形态结构,可以用来进行牙髓生物学、牙科材料毒理学等研究。     

重组人骨形成蛋白－2与异种骨复合移植的扫描电镜观察

目的：明确含有重组人骨形成蛋白－２（ｒｈＢＭＰ－２）的新型复合异种骨的骨修复能力。方法：将ｒｈＢＭＰ－２与经综合化学处理的新生小羊骨松质（ＣＢ）结合，制备成复合异种骨．将复合异种骨植人兔下颌骨缺损，并以单纯松质骨移植、自体骨移植作为对照组，术后２、４、８、１２周分别取材做扫描电镜观察。结果：复合异种骨移植后，植骨区有大量新骨形成，新骨的量随移植时间延长而逐渐增多。自体骨移植组扫描电镜下表现与复合异种骨组基本相同。而单纯骨松质载体移植后，植入区多为纤维结缔组织，新骨形成少．结论：ｒｈＢＭＰ－２可显著促进复合异种骨内的新骨形成。这种新型复合异种骨可能是一种较理想的植骨材料，可望用于人体植骨     

hBMP-7基因转染对骨髓间充质干细胞增殖和碱性磷酸酶合成的影响

目的探讨逆转录病毒介导的人骨形态发生蛋白7(humanbonemorphogeneticprotein7,hBMP-7)基因转染对兔骨髓间充质干细胞(bonemarrowmesenchymalstemcell,BMSc)增殖和向成骨细胞分化的影响。方法构建hBMP-7逆转录病毒载体,使用含目的基因的病毒液感染BMSc,免疫组织化学方法检测hBMP-7蛋白的表达,MTT法检测细胞增殖能力,使用流式细胞仪检测细胞周期,NPP法检测碱性磷酸酶合成情况。结果经BMP-7基因转染的兔BMSc有hBMP-7的阳性表达,增殖能力无明显改变(P>0.05),但其合成碱性磷酸酶的能力得到显著提高,与空载体病毒液转染、未经转染的BMSc相比差异有显著性(P<0.01)。结论经BMP-7基因转染的BMSc能够表达外源BMP-7,hBMP-7基因转染能够促进体外培养的BMSc向成骨细胞转化,可用于以BMSc为种子细胞的组织工程化骨组织的构建。     

人牙髓细胞的体外培养及生物学特性研究

目的:从年轻恒牙的牙髓组织中分离培养牙髓细胞,研究其表型及生物学特性.方法:选取因正畸或阻生拔除的年轻健康双尖牙或第三磨牙,取出牙髓,组织块酶消化法分离培养人牙髓细胞,免疫细胞化学检测第3代人牙髓细胞表面标志,并对体外培养的人牙髓细胞的矿化能力进行研究.结果:体外培养的人牙髓细胞表达Ⅰ型胶原及波形丝蛋白,少数细胞增殖可...     

Construction of Adeno-associated Virus System for Human Bone Morphogenetic Protein 7 Gene

To construct the recombinant adeno-associated virus （rAAV） vector with human bone morphogenetic protein 7 （BMP7） and observe the BMP7 mRNA expression in vitro, BMP7 CDS sequence was cloned into expression plasmid pAAV-MCS of AAV Helper Free System. The recombinant plasmid was identified with enzyme digestion and sequencing. The recombinant plasmid, pAAV-RC, pHelper were co-transfected into AAV-293 cells according to the calcium phosphate-based protocol. The viral stock was collected by 4 rounds of freeze/thaw. After purified and concentrated, the recombinant virus titer was determined by dot-blot assay. HEK293 cells were transfected with the recombinant virus at different MOI, and the expression of BMP7 mRNA was detected by RT-PCR. The results showed rAAV-BMP7 was constructed and packaged successfully. The physical particle titer was 2.5×10^11 vector genomes/mL. There was different expression level of BMP7 mRNA after transfecton. These data suggested that recombinant AAV mediated a stable expression of hBMP7 mRNA in 293 cells. The AAV production method may pave the way of an effective strategy for the jaw bone defection around dental implants.     

骨形态发生蛋白微球对兔骨髓基质细胞生物学行为的影响

目的研究骨形态发生蛋白微球对兔骨髓基质细胞生物学行为的影响。方法将壳聚糖与海藻酸钠制成复合微球,包裹或不包裹骨形态发生蛋白。采用体外细胞培养技术,将两种微球分别与细胞一起培养,通过对细胞增殖率及碱性磷酸酶活性、考马斯亮蓝的检测,观察两种微球对培养细胞的影响。结果两种微球对骨髓基质细胞的增殖均无明显影响,但骨形态发生蛋白微球对细胞的分化及分泌功能有明显的促进作用。结论骨形态发生蛋白能够提高骨髓基质细胞的体外成骨能力,且壳聚糖海藻酸钠微球可作为骨形态发生蛋白的良好载体。     

DEX和rhBMP2对体外培养人牙髓细胞碱性磷酸酶活性的影响

目的 探讨不同浓度地塞米松(Dexamethasone,DEX)、重组人骨形态发生蛋白2(recombinant human bone morphogenetic protein 2,rhBMP2)及两者联合应用对体外培养的人牙髓细胞(human dental pulp cells,HDPCs)碱性磷酸酶(Alkaline Phosphatase,ALP)活性的影响.方法 组织块法培养HDPCs并进行鉴定;采用酶动力学的方法,观察 DEX、rhBMP2及二者联合应用对HDPCs的ALP活性的影响.结果 单独应用DEX时ALP活性明显增高,且在生理浓度范围内当浓度为0.01 nmol/ml时,对HDPCs的ALP活性达到最大的刺激作用,rhBMP2对HDPCs的ALP活性呈浓度依赖性增强;当联合应用DEX和rhBMP2,ALP活性比单独应用相应浓度的rhBMP2明显增高.结论 DEX、rhBMP2对HDPCs的ALP活性均有增强作用,同时二者对HDPCs的ALP活性有显著的功能放大性协同增强作用.