| PrefaceDental papilla mesenchymal cells differentiate into primary odon-toblasts and form primary dentin during tooth development. After e-ruption, a certain fraction of pulp cells differentiate into odontoblasts and form secondary dentin. Investigations suggested that some growth factors might modulate proliferation and matrix synthesis in pulp. However the precise mechanisms remain unknown. Scholars have described the spatial - temporal expression of basic fibroblast growth factor (bFGF) during odontogenesis of mouse and human embryo as revealed by immunohistology. They believed that bFGF was involved in the odontoblast differentiation and dentin matrix deposition. But study on the expression and distribution of bFGF in pulps of permanent teeth during root development has not been reported. The purpose of this study was to discuss the significance of bFGF in the development and maturation of dental pulp.For the first time, by use of immunohistochemical and image a-nalysis techniques, we presented the expression and distribution pattern of bFGF in pulps of permanent teeth at different root development stage.Materials and MethodsDental pulps were obtained from healthy caries - free permanent teeth in need of extraction. All subjects had no systematic disease and didn' t take any immune - inhibited drugs within three months. Based on the root development status, the pulp tissue was classified into three groups; root just starting development, root being in development and root finishing development. After extracted, the dental pulp was rapidly removed, then fixed in 0. 4% paraformaladehyde ( pH 7.4) at4C for 48 hours. Tissue blocks were dehydrated in ascending series of ethanol, cleared in xylene and embedded in paraffin. Serial sections were cut 5um thick. Anti - human poly clone antibody was used as the primary antibody and SP immunohistochemistry method was used for staining. The samples were observed under light microscope. Meta Morph/cool snapfx/AX70 image analysis software was used to detect the gray value of bFGF positive stained in dental pulp. The data were statistically analyzed by use of SPSS.ResultsStaining of immunohistochemistry for bFGF in dental pulps revealed that there were positive reactions in the cytoplasm of fibroblast, odontoblast, and epithelial cells in blood vessel wall and in extracellular matrix as well. Staining was strongly positive in immature permanent teeth, especially at the stage of root just starting development. The number of fibroblasts in positive expression was the most in them, and the least in the mature permanent teeth.Image analysis indicated that with the development of root formation , the gray value of the positive reaction in three groups were higher and higher and were significantly different ( P <0. 001) . For the first group, the gray value of the outer part was higher than that of the pulp core. For the second group, the pulp core has a higher gray value in the coronal pulp, while a lower value in root pulp compared to the outer parts. For the third group, there was no statistical difference between gray values in different pairts.DiscussionStudies of pulp cells in cultures indicated that adding bFGF enhanced DNA synthesis, whereas decreased ALPase level. ALPase may induce the terminal differentiation and calcification of pulp cells. Because terminal cells lose proliferate activity, the inhibition of terminal differentiation by bFGF may be a prerequisite for the recruitment of pulp cells during tooth development and repair.Recent investigations suggested that bFGF might be involved in tooth morphogenesis and differentiation of tooth - forming cells. By immunohistology we observed bFGF staining in pulp fibroblasts. With development of the root, the cell number expressed bFGF becomes less and the staining intensity weaker. It appears that bFGF may play a role in the development and maturation of pulp cells. The results indicate that when the young permanent teeth initially develop, bFGF positive expression in pulp core is strong...
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