感染根管内细菌定植状态的观察

Status of bacterial colonization in infected root canal

目的：了解慢性根尖周炎患牙根管内的细菌感染状态,以指导临床治疗和评估预后。方法：采用组织学与扫描电镜相结合的方法对临床不能保留的7例慢性根尖周炎患根进行超微结构观察,将新鲜拔除的患根沿牙长轴近、远、中向劈为两半,一半做组织学切片,采用Brown＆Brenn染色观察,另一半做扫描电镜观察。结果：组织学切片细菌特染显示,大量细菌附着于根管壁表面并定植于根管壁牙本质小管深部,用测微尺测量细菌侵入深度为140~1 000μm,根尖1/3段感染较重。扫描电镜结果显示,根管壁表面可见到致密、半封闭状态的网状细菌膜结构,大量球菌、杆菌和/或丝状菌镶嵌于无定形的基质中,集中于根尖1/3段。结论：慢性根尖周炎的根管内细菌以生物膜形式定植在根尖1/3区,并侵入牙本质小管深部,形成感染难以清除的区域。

Objective： To investigate the morphology,distribution and relative position of the bacteria in infected root canals with chronic apical periodontitis and make some clinical inferences.Methods： Seven extracted roots with chronic apical periodontitis were collected.Immediately after extraction,all specimens were rinsed in sterile saline solution.The remaining tooth crowns were cut off with carborundum disks under water spray.Longitudinal grooves following the root length axis were cut along the entire root by using tapered diamond burs under water spray,and the roots were then split with a chisel into two halves.One half of the roots were decalcified,and after dehydration and embedding in paraffin,serial sections of 4 μm were cut,parallel to the long axis of the roots.The sections were stained using the Brown Brenn methods,which were examined with a light-transmitting microscope for the distribution of bacteria in the root canals.The other half of the roots were dehydrated,sputtered coated with gold,and then examined for the occurrence of bacteria in the root canals using a scanning electron microscope.Results： Histobacteriologic observation showed that bacteria were found in all the seven specimens,which were clogged with a dense bacterial biofilm in the apical third of the main canal.Bacteria could penetrate into the dentinal tubules about 140-1 000 μm.Scanning electron microscopy observation showed that bacteria consisting of cocci,rods and/or filaments with amorphous materials formed the typical biofilm structure in the apical third of the root canals.Conclusion：The findings support the view that bacteria colonizing the root canal system play an essential role in the pathogenesis of periradicular diseases.In all the seven specimens,bacteria usually formed dense aggregates on the root canal walls,penetrating the dentinal tubules in the apical third of the main canal.Dense bacteria and amorphous materials filled the inter-bacterial spaces and formed the typical biofilm structure.