Ultrastructure of regenerated junctional epithelium after surgery of the rat molar gingiva.

To elucidate the ultrastructure of reconstructed dentogingival junction and cytological details of regenerated junctional epithelium (RJE) and to discuss the functional aspects of RJE through comparing its fine structure with normal structure, molar gingivae of 15 Wistar rats were examined by electron microscopy at 6, 8 and 12 weeks after electrosurgical gingivectomy. As early as 6 weeks after surgery, the epithelial architecture of dentogingival junction was reestablished at the light microscopic level, and RJE showed the ultrastructure indistinguishable from that before surgery. The cytoplasmic vacuoles, characteristic of rat JE, displayed the morphology, distribution and intimate relationship with lysosomes, all of which were quite identical to those in controls, and were regarded to represent "phagosomes." Since various findings specific to JE are apparently reproduced in RJE, it seems that those peculiar structures would be an expression due to the environment rather than to the predetermined nature. RJE also might play a defensive function through the endocytic-vacuolar system as suggested for normal JE. The presence of two types of cuticular structures, which were not conspicuous in normal JE, was also revealed between RJE and the tooth.