BMP-2/VEGF纳米控释系统复合MTA诱导牙髓再生的实验研究

when teeth suffer injuries, such as trauma, deep cavity preparation or severe caries lesions the odontoblasts may succumb, possibly leading the dental pulp to irreversible pulpitis or necrosis .Generally,conventional endodontic therapy is indicated in such situations. Despite the positive results observed following endodontic treatment, there are significant drawbacks . This is especially critical when dealing with dental trauma in young patients with immature teeth, a frequent occurrence in clinical dental practice. In order to avoid such problems and aiming at maintaining the tooth vital . . The dental pulp is a highly specialized mesenchymal tissue characterized by the presence of odontoblasts and by the fact that it is surrounded by a rigid mineralized tissue . The dental pulp is infiltrated by a network of blood vessels and nerve bundles emanating from the apical region . The possibility of pulp tissue regeneration is restricted by several factors . Due to anatomical arrangement of pulp chamber, the dental pulp has minimal collateral blood supply, impairing the ability of the immune system to combat infections . Furthermore, odontoblasts are post-mitotic cells that have limited (or no) ability to proliferate . The tooth reparative competence is observed when superficial carious lesions stimulate odontoblastic cells to increase their secretory activity . If suitable conditions prevail, odontoblasts elaborate reparative (tertiary) dentin, a more poorly organized and mineralized matrix compared to primary and secondary dentin . The new dentin serves to protect the pulp from bacterial by-products and/or the actual bacteria.. With the development of new pulp capping,it brings new hope to reserve vital teeth,However,they cannot achieve true clinical significance of the dental pulp regeneration.Because of rHBF(Recombinant Human Bioactive factor) having come out and developing of drug controlled release , They have given more opportunities to the treatment of dental pulp regeneration.We Selected two factors ,BMP-2 and VEGF which play a key role in the process of pulp formation and vascularlization ,as a tool of drugs, and prepare PLGA nanoparticles in controlled release systems with different release rates, complex inorganic oxide polymer a new capping agent (MTA)；We will establish MTA and MTA directing adsorption of BMP-2 and VEGF as two different group controll,through bio-reactor, we will observe rat dental pulp stem cells cultured in vitro and interaction of composite material.By rat dorsal subcutaneous, observation of composite end closed, to the spinal cord induced by ectopic tissue growth of root canal.Last established hybrids fangs spinal cord one-third cut, and half cut animal model, observation composites induced by pulp organization regeneration of situation, using Micro- CT, and histological, analysis the structure of fresh human pulp tissue, gradually filter double factor Nano-controlled release system promoting pulp regeneration

新型盖髓剂的发展为更多活髓保留带来了新的希望，却不能实现真正临床意义上的牙髓再生。重组人生物活性因子的相继问世和药物控释技术的发展给牙髓再生治疗提供了机遇。本项目选择在牙髓形成与血管化过程中起关键作用的生长因子BMP-2和VEGF为工具药物，制备具有不同释放速率的PLGA纳米控释系统，复合新型盖髓剂无机三氧化聚合物（MTA），设立单纯MTA、MTA直接吸附BMP-2和VEGF为对照，通过生物反应器，观察体外培养的大鼠牙髓干细胞与复合材料的相互作用；通过大鼠背部皮下移植，观察复合材料单端封闭，诱导异位组织向去髓牙根髓腔生长的能力；最后建立杂种犬牙髓1/3切、半切动物模型，观察复合材料诱导牙髓组织再生的情况，利用牙科CT、组织学检查等方法分析新生牙髓组织的结构，逐步筛选双因子纳米控释系统促进牙髓再生的剂量与释药标准，为利用生物学方法实现牙髓再生提供研究基础，为生物活性盖髓剂的研发提供经验

新型盖髓剂的发展为更多活髓保留带来了新的希望,却不能实现真正临床意义上的牙髓再生。重组人生物活性因子的相继问世和药物控释技术的发展给牙髓再生治疗提供了机遇。本项目选择在牙髓形成与血管化过程中起关键作用的生长因子 BMP-2 和 VEGF 为工具药物,制备具有不同释放速率的 PLGA 纳米控释系统,复合明胶及新型盖髓剂无机三氧化聚合物(MTA),通过生物反应器,观察体外培养的牙髓干细胞与复合材料的相互作用;通过裸鼠背部皮下移植,观察复合材料单端封闭,诱导异位组织向去髓牙根髓腔生长的能力;最后建立杂种 犬牙髓 1/3 切、半切动物模型,观察复合材料诱导牙髓组织再生的情况,利用牙科 CT、组织学检查等 方法分析新生牙髓组织的结构,逐步筛选双因子纳米控释系统促进牙髓再生的剂量与释药标准。通过o-w和w-o的方法制备具有不同释放速率的PLGA微球、利用纳米纤维明胶的吸附能力，成功制备了BMP2和VEGF的单组份及双组份控释系统。PLGA、明胶纳米纤维支架复合控释系统体外释放实验证实活性生长因子的释放时间可持续在两周、甚至更长时间。传统MTA直接盖髓8周左右可见牙本质桥的形成，然而双组份控释系统4周时可见到明显的牙髓样组织生成。同时，实验中发现VEGF具有明显的牙髓细胞的趋化作用。明胶的使用提高了生长因子的携带量同时由于其可以降解为牙髓的再生提供了生理空间。本研究为利用生物学方法实现牙髓再生提供研究基础,为生物活性盖髓剂的研发提供经验。