A Study On Nuclear Factor Of Active T Cells NFATc1 Express During The Replacement Of Dogs' Primary And Permanent Teeth

The replacement of primary and permanent teeth is an important and complicated physiological phase that belongs to the growth and development of teeth and maxillofacial region. A series of changes have taken place in the correlated tissues including the primary teeth roots,dental pulp,periodontal ligament,alveolar bone,the successional permanent teeth germs and dental sac during this procedure, leading to the absorption of primary teeth roots and the exfoliation of primary teeth, the constantly occlusal movement of permanent teeth germs through the eruption passage and finally erupted.But the mechanisms are not fully clarified.At present, it has been confirmed that osteoclasts (OC) and odentoclast (OD) are two important functional cells involved in the physiological absorption of primary teeth root and the formation of the tooth eruption passage.OD is similar to OC in histology,function and other parts, so the study on OC and OD is an important aspect of the reaserch about the the replacement of deciduous teeth and permanent teeth mechanism.Now many cytokines are refined stimulating osteoclast to generation,proliferation.,differentiation,activation and bone resorption. The Nuclear Factor of Active T cells(NFAT) was first discovered in T cells and confirmed to has close association with the immune system in the earlier period, and the NFATc1,one member of the NFAT family,has been identified to play a very important role in the process of osteoclasts fusion, differentiation,maturation and so on in recent years. In vivo,NFATc1 are not only a necessary signaling molecules in the RANKL signal pathway(the main signal transduction pathway of osteoclast differentiation),but even in the absence of RANKL circumstances, NFATc1 can also promote osteoclast differentiation.At present,the study of NFATc1 in the system of bone metabolism focuses on promoting the role of bone resorption of the OC,but until now there is not any report concerning about this transcription factor in the replacement of primary and permanent teeth.Immunohistochemical technique method were used in this study to observe the NFATc1 expression in deciduous teeth,periodontal ligament, alveolar bone and permanent teeth germs under three states of the dogs' teeth:primary dentition roots stability, the process of the replacement of primary and permanent teeth,permanent dentition ,for researching NFATc1's role and influence in the process of the replacement of primary and permanent teeth preliminary.The main content and results of this research are as belows:â‘ Dogs' primary dentition roots stability stage group: the deciduous teeth roots were integrity and were not absorbed physiologically. A small amount of the multinucleated osteoclasts located in lacunae of the alveolar bone near or at the top of the germs, NFATc1 positive signals were seen in them.The succeeded permanent teeth germs were in developing phase and the coronal dentin and enamel matrix started to form,odontoblasts and ameloblasts aligned along dentin and enamel orderly,appeared to tall posts and the nuclears were away from the basement membrane, polarity inversd, NFATc1 positive signals were seen in the odontoblasts,ameloblasts and dental crypts.These results indicated that NFATc1 involved in the absorption of the alveolar bone and the development of dogs' permanent teeth germs during the stages of the primary dentition roots stability. â‘¡Dogs'primary and permanent teeth replacement stage group:dogs' deciduous teeth roots were under going absorbed physiologically and it could be seen that the odentoclasts located in the absorbed lacunae on the roots, with strong NFATc1 positive signals. The alveolar bone around the deciduous teeth roots,the dental crypts and the permanent teeth germs were undergoing active absorbed,there were a lot of absorbed lacunae with strong NFATc1 positive signal's multinucleated osteoclasts.The succeeded permanent teeth germs were continue developed and the coronal dentin and enamel went on forming and calcifying.Ameloblasts and odontoblasts aligned along dentin and enamel orderly,appeared to tall posts and the nuclears were away from the membranes conspicuously.The NFATc1 positive signals were observed on the odontoblasts,ameloblasts and dental crypts.At the same time,we found that the osteoblast on the alveolar bone around the deciduous teeth roots and the permanent teeth germs were displayed strong NFATc1 positive signals.The signal about osteoclasts are stronger than primary dentition roots stability stage with a significant difference(P<0.05),this result indicated that osteoclasts and odentoclasts were active in this period, NFATc1 play a very important role in the process of the osteoclasts and odentoclasts' generation,fusion, differentiation,maturation and function, finaliy lead to the resorption of the alveolar bones and the deciduous teeth roots.The results of the NFATc1 positive signals on the odontoblasts,ameloblasts and dental crypts indicated that NFATc1 involved in the development of dogs' permanent teeth germs during the stages of primary and permanent teeth replacement. this stage,on the one hand NFATc1 involved in the function of OB in the alveolar bone alterations,on the other hand osteoblasts are closely related to the osteoclasts' generation, differentiation and maturation and function activities, NFATc1 may play roles in the process of the osteoclasts and odentoclasts' generation,fusion, differentiation,maturation and function by the actions with OB, the specific mechanisms for further study.â‘¢Dogs'permanent teeth dentition stage group:dogs' deciduous teeth shed and permanent teeth erupted, osteoclasts on the alveolar bones were weakly positive and osteoblasts were negative.The results indicated that in this stage the quantity of NFATc1 was conspicuous reduced and the major changes of the alveolar bones were the bone remodeling leading by the function of osteoblasts,and may suggest that the NFATc1' effect that involved in the in the alveolar bone alterations leading by OB are weaker than play roles in the process of the osteoclasts and odentoclasts' generation,fusion, differentiation,maturation and function by actioning with OB.All these These results suggest that NFATc1 involves in the osteoclasts and odentoclasts' generation,fusion, differentiation,maturation and function,and plays a important role in the parts of the replacement of dogs' primary and permanent teeth ,such as the resorption and rebuilding of the alveolar bone,the physiological absorption of the deciduous teeth roots,the development of dogs' permanent teeth germs,and so on.