神经生长因子对比格犬年轻恒牙牙髓组织再生的促进作用

目的：建立比格犬年轻恒牙根尖周炎模型，探讨神经生长因子（NGF）对比格犬年轻恒牙牙髓组织再生的影响，阐明其作用机制。方法：选择6只比格犬符合标准的12颗恒牙作为研究对象，将其分为对照组、水凝胶组和水凝胶复合NGF组，每组2只犬4颗恒牙。对照组不建模；水凝胶组建立根尖周炎模型，给予单纯水凝胶处理；水凝胶复合NGF组建立根尖周炎模型，给予NGF复合水凝胶处理。采用HE染色观察各组实验牙组织学变化，测定各组实验牙再生组织长入深度和再生组织面积。结果：比格犬年轻恒牙根尖周炎模型建立成功。对照组牙根管内牙髓组织正常，有成纤维细胞、成牙本质细胞和血管组成；水凝胶组牙根尖部无新形成硬组织，根尖周出现纤维修复；水凝胶复合NGF组牙根管内有新形成的硬组织，可见牙骨质细胞样细胞和牙骨质基质陷窝，根管内可见游离的牙骨质样组织，牙根管内新形成的软组织主要为血管和成纤维细胞。水凝胶复合NGF组牙再生组织长入深度和再生组织面积均高于水凝胶组（t=66.261，P<0.01；t=60.363，P<0.01）。结论： NGF具有促进比格犬年轻恒牙根尖周炎牙髓组织再生的作用。

Promotion effect of nerve growth factor on regeneration of young permanent dental pulp tissue in Beagle dogs

Objective:To establish models of young periapical periodontitis in the Beagle dogs and to explore the effects of nerve growth factor (NGF) on the regeneration of young permanent teeth pulp tissue of the Beagle dogs, and clarify the action mechanism. Methods:Twelve permanent teeth of 6 Beagle dogs were selected and divided into control group, hydrogel group, and hydrogel combined with NGF group, with 4 permanent dental of 2 Beagle dogs in each group.The teeth in control group were not treated.The teeth in hydrogel group were established the periapical periodontitis models and were treated with hydrogel alone.The teeth in hydrogel combined with NGF group were established the models of periapical periodontitis and treated with NGF combined with hydrogel.The histological changes of the experimental teeth in various groups were observed by HE staining.The depth of regenerated tissue and the area of regenerated tissue of the experimental teeth in various groups were measured. Results:The young permanent periapical periodontitis models of Beagle dogs were successfully established.In control group,the dental pulp tissue in the root canal was normal, and it was composed of fibroblasts, odontoblasts and blood vessels;in hydrogel group,there was no new hard tissue formed at the apex, and fiber repair occured at the apical period;in hydrogel combined with NGF group, there was newly formed hard tissue in the root canal,the cementoblast-like cells and the cementum matrix lacuna could be seen,the free cementum-like tissue was seen in the root canal,and the newly formed soft tissue in the root canal was mainly the blood vessels and the fibroblasts. The depth of regeneranted tissue and the area of regenerated tissue in hydrogel combined with NGF group were higher than those in hydrogel group (t=66.261,P<0.01;t=60.363,P<0.01). Conclusion:NGF has the effect of promoting the regeneration of dental pulp tissue of young permanent periapical periodontitis of the Beagle dogs.