Histopathologic Study on Experimental Periodontitis in Rats

Abstract

The changes of periodontal tissues in rats induced by local irritations were studied histologically. Local irritants were consisted of a rubber thread and a silk thread. In the distal cervical part of lower M1, rubber thread insertion during 2 days was followed by silk thread insertion during 2 weeks. The histopathologic observations were performed from the time of initial irritation to one month after a silk thread was removed.
In 2 days after a rubber thread was inserted, the destruction of junctional epithelium, inflammatory cell infiltration in periodontal ligament, destruction and degeneration of connective tissue and alveolar bone resorption by osteoclast were observed at the distal site of M1.
In 2 days after rubber thread insertion and in 2 days after silk thread insertion, marked inflammatory cell infiltration and many osteoclasts were observed at the distal site of M1 and mesial site of M2.
In 2 days after rubber thread insertion, the number of osteoclasts and that of inflammatory cells were correlated significantly.
In 2 weeks after silk thread inserted, deep periodontal pocket with horizontal bone resorption was observed.
In one month after silk thread was removed, the down growth of junctional epithelium at the mesial site of M2 was observed. The extent of the down growth at the mesial site of M2 was foundless than that at the distal site of M1.