Guo Hui Jie, Wang Jia De
Department of Stomatology, Peking University People's Hospital, Beijing 100044, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2009 Oct 18;41(5):571-4.
To investigate the patterns of microbial infection on the apical external root surfaces of treated and untreated teeth associated with chronic apical periodontitis and to study bacteria in the biofilm in order to find out the species, constitution and origination of bacteria in periapical biofilm.
Ten teeth with chronic apical periodontitis from patients of the Department of Stomatology of People's Hospital, Peking University: 5 untreated teeth with a radiographically visible chronic periradicular lesions and 5 teeth with extensive carious lesions, radiolucent lesions of varying sizes and attached periradicular tissues were selected for study. Using aseptic techniques and sterile instruments, bacterial samples of the root canals were taken, inoculated and separated according to usual practice. After extraction, ten teeth were fixed and the apical 5 mm portion of one root was sectioned. Root tips were dehydrated, sputter coated with gold, and then examined for the occurrence of bacteria on the apical root surfaces using scanning electron microscope. Five healthy teeth with vital pulp were used as controls.
Microbial study showed that ten specimens yielded bacterial growth. The most prevalent bacteria were P. micros and F. nueleatum. In the 5 untreated teeth, bacterial cells were usually observed close to the apical foramen in only 1 specimen. Morphologically, these bacteria consisted of cocci. In the 5 treated teeth, a dense bacterial aggregation composed mainly of cocci and rods was observed surrounding the apical foramen of all specimens. Besides rods, other bacterial morphological types were recognized, including coaggregations of cocci and filaments, characterizing a fully developed "corn-cob". No microorganisms were found in the healthy controls.
Bacterial biofilm was always present in teeth with post-treatment endodontic disease. The presence of apical bacterial biofilm is clinically important, and it may cause failure of endodontic treatment as a consequence of persistent infection.
研究慢性根尖周炎患牙治疗与未治疗情况下根尖外牙根表面的微生物感染模式，并对生物膜中的细菌进行研究，以明确根尖生物膜中细菌的种类、构成及来源。
选取北京大学人民医院口腔科患者的10颗慢性根尖周炎患牙：5颗未经治疗且X线片显示有慢性根尖周病变的牙齿，以及5颗有大面积龋损、不同大小透射性病变并伴有根尖周组织附着的牙齿用于研究。采用无菌技术和无菌器械，按常规方法采集、接种并分离根管细菌样本。拔牙后，将10颗牙齿固定，截取其中一根根尖5mm部分。根尖进行脱水、喷金镀膜处理，然后用扫描电子显微镜检查根尖牙根表面细菌的存在情况。选取5颗牙髓活力正常的健康牙齿作为对照。
微生物学研究显示，10个样本均有细菌生长。最常见的细菌是微小微单胞菌和具核梭杆菌。在5颗未经治疗的牙齿中，仅1个样本在根尖孔附近观察到细菌细胞。从形态学上看，这些细菌为球菌。在5颗经治疗的牙齿中，所有样本的根尖孔周围均观察到主要由球菌和杆菌组成的密集细菌聚集。除杆菌外，还识别出其他细菌形态类型，包括球菌与丝状菌的共聚体，呈现出成熟的“玉米棒”特征。健康对照中未发现微生物。
根管治疗后疾病的患牙中始终存在细菌生物膜。根尖细菌生物膜的存在具有临床重要性，它可能因持续感染导致根管治疗失败。
