| Implantation of artificial tooth roots has been widely applied in dental surgery to recover the lost functions of a natural tooth. A familiar method of direct implantation, the so-called " osseointegration," aims at fixing the root in the submaxilla. And some problems have been reported in that the direct impact of occlusal and bruxing forces has often caused absorption of the alveolar bone and loosening of the implant by excessive stress between the artificial titanium root and the jaw bone.As all known,anatural tooth has a periodontal ligament (PDL) between the cementum and alveolar bone, mainly consisting of active fibroblasts and collagen fibers,and plays quite an important role as a shock absorber against the mastication impact and as a receptor of forces. Therefore, it is desirable that artificial roots have such functions as the PDL.Recently with the rapid development of tissue engineering, it is desirable that biointegrated implant cound increase indications of dental implantology and reduce failed frequency. In this study,we attempted to prepare ligament-like structure construction in the dental implant-bone interface in vitro.At first,the/three dimensionallycultured model of human periodontal ligament cells was established to evaluate the feasibility of polyglycolic acid as the scaffolds. Materials and Methods:The human periodontal ligament cells were seeded and cultured onto PGA three-dimensional scaffold, and then the cellular morphology and structure , adhesion andbiocompatibility with scaffolds were evaluated by light microscope and scanning electronic microscope, and the cellular type I collagen synthesis was observed by method of immunohistochemical staining with anti-type I collagen antibody. Results and Conlusion:The human periodontal ligament cells adhere to scaffold well and exhibit the excellent matrix secretion ability under light microscope and scanning electronic microscope. Type I collagen was expressed positively in cell-scaffold complex by immunohistochemical staining. PGA scaffold showed excellent adhesiveness and biocompatibity, on which human periodontal ligament cells could maintain its morphological and biological property, so it is suitable in constructing periodontal ligament in tissue engineering in the future. Discussion:Cells can grow normally with the extracellular matrix (ECM) existing to support them under three dimensional environments in vivo, whereas there were quite different biological characteristics in a conventional monolayer cultivation in vitro. Three dimensional cultivation has been defined as "Isolated and expanded cells adhere to the temporary scaffold in all three dimensions, proliferate, and secrete their own extracellular matrices (ECMs), replacing the biodegrading scaffold." PDL cells are foundation of periodontal regeneration, so 3D cultivation of them will be critical in periodontal tissue engineering. Three-dimensional scaffolds play an important role in tissue engineering as an adhesive substrate for implanted cells and a physical support to guide the formation of new organs. The chosen materials which compose three-dimensional scaffolds profoundly affects cells and tissue regeneration. In addition to possessing better biocompatible and biodegradable properties, the scaffold should be highly porous with a large surface-to-volume ratio to facilitate cell adhesion, promote cell growth, and allow retention of differentiated cell functions. It has been widely recognized that pore size of the scaffolds must be from 50 to 100um and porosity be higher than 90%. Appropriate scaffolds are not only permeable to permit the equally ingress of cells and nutrients but also redound to cell attachment for one another. It promotes the development ofvnew tissue and prevents the cellular dedifferentiation phenomenon. The results of this research wound firstly apply to periodontal regeneration and rebuild for patients suffered from periodontal defect, then promote the development of dental implantology.
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