Development of focal infection model result from infected root canal-associated bacteria on compromised hosts.

对环孢素A （Cyclosporin A, CsA）诱导的免疫抑制与未治疗或残留的根尖周围病变的相关性进行了三维时间研究，并进行了组织病理学分析。CsA治疗明显抑制病变扩大。在停用CsA后，对照组的病变大小增加了相同程度。此外，组织病理学观察显示，CsA给药量的差异没有太大影响。然而，CsA处理导致纤维组织细胞间物质增多，特别是20mg/Kg/d给药组。在体外对7种感染根管相关细菌（RCB）对杜胶点（GP）的生物膜形成能力进行了形态学研究。粪肠球菌最常形成生物膜，而无骨梭杆菌或痤疮丙酸杆菌根本不形成生物膜。采用细菌学方法评价了5种RCB对小猎犬根外GPs的生物成膜能力。71.4%的标本检出粪肠球菌，是根外区最适宜形成生物膜的细菌。根据他们的研究结果，准备给药醋酸甲基强的松龙的中毒动物，研究从根外粪肠球菌生物膜分离的浮游巴伐利亚菌引起的菌血症。给药4周后，未引起菌血症，而浮游粪肠杆菌细胞在根尖周围病变处植入约10^3倍的生物膜细菌，成为持续菌血症。进一步研究药物浓度和给药时间，并不断寻找由根外生物膜引起的菌血症。

Correlation between Cyclosporin A (CsA)-induced immunosuppression and untreated or residual periapical lesions has been investigated 3 dimensionally with time, and histopathological analysis were performed. CsA treatment significantly inhibited lesion expansion.. Agter withdrawal of CsA, the lesion increased in size to a same extent in a control group. In addition, histopathological observation revealed that the difference of CsA administration volume did not affected much. However, CsA treatment induced intercellular substance in fibrous tissue to be voluminous, especially in 20mg/Kg/day administration group.In vitro, biofilm forming capacity of 7 infected root canal-associated bacterial (RCB) species to gutta-percha points (GP) was investigated morphologically. Enterococcus faecalis formed most frequently biofilm, but Fusobacterium uncleatum or Propionibacterium acnes did not form it at all. The biofilm forming capacity of 5 RCB species to extraradicular GPs on beagle dogs were evaluated by bacteriologic technique. E. faecalis identified in 71.4% of the examined samples, and was most suitable biofilm forming bacterium in extraradicular area. According to their results, compromised-animals to be administrated methylpredonisolon acetate were prepared for investigation of bacteremia by which planktonic bavteria detached from extraradicular E. faecalis biofilm caused. For 4 weeks administration, bacteremia was not induced, whereas planktonic E. faecalis cells insertion of about 10^3 times biofilm bacteria on GP in vitro in the periapical lesion became continuously bacteremia. Drug concentration and administration period were further studied, and we are continuously searching bacteremia caused by extraradicular biofilm on compromised-animal.