根管治疗失败病例根管内细菌对根尖周组织致病力的实验研究

目的观察根管治疗失败病例根管内分离的主要微生物对狗牙根尖周组织的影响。方法选择成年健康杂种狗5只，共有40个实验牙，80个实验牙根。实验一组于狗牙根管内接种溶血链球菌、微小消化链球菌、产黑色素类杆菌及具核梭杆菌；实验二组于狗牙根管内接种粪肠球菌及上述4种细菌；对照组不接种细菌。对狗牙完成根管治疗。分别于治疗后3、6、12个月拍摄根尖X线片，并记录牙齿和根尖周组织的临床表现；根管治疗后12个月处死动物，制备根尖周组织病理标本，观察根尖周骨组织破坏情况；动物处死前，根管内进行微生物的取样、培养和鉴定。结果实验组可见狗牙槽骨尖周骨质吸收，牙周膜纤维排列受到破坏，实验二组对根尖周破坏重于实验一组，对照组根尖周骨组织无破坏。结论从根管治疗失败病例根管内分离的主要微生物粪肠球菌、溶血链球菌、微小消化链球菌、产黑色素类杆菌及具核梭杆菌对狗牙根尖周组织有明显的破坏作用。

Experimental study of the capacity to induce apical periodontitis in dogs by bacterial strains from failed endodontic tooth

Objective To determine the influence of the microbial flora isolated from failed endodontic tooth to dogs＇ apical tissue. Method In five dogs,80 root canals were selected. The first experimental group （32 root canals） was inoculated with a combination of four bacterial strains belonging to species Streptococcus hemolytic, Peptostreptococcus micros, Bacteroides melaninogenicus and Fusobacterium nucleatum. The second experimental group （32 root canals） was inoculated with a five-strain combination consisting of the above 4 strains and a strain of Enterococeus faecalis. The control group （ 16 root canals） was not inoculated. All the root canals were applicated with endedontic treatment. After 3,6 and 12 months, the reaction in the periapical region was radiographed. After 12 months,survival of the strains was recorded bacteriologically, and histopaxthologic study was performed to the periapical region. Result The periapical region of experimental group was damaged. Conclusion The periapical region of dogs was damaged by the main bacteria isolated from failed endodontic tooth.