Nair P N R
Institute of Oral Biology, Section of Oral Structures and Development, Centre of Dental and Oral Medicine, University of Zurich, Zurich, Switzerland.
Int Endod J. 2006 Apr;39(4):249-81. doi: 10.1111/j.1365-2591.2006.01099.x.
Apical periodontitis is a chronic inflammatory disorder of periradicular tissues caused by aetiological agents of endodontic origin. Persistent apical periodontitis occurs when root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. Problems that lead to persistent apical periodontitis include: inadequate aseptic control, poor access cavity design, missed canals, inadequate instrumentation, debridement and leaking temporary or permanent restorations. Even when the most stringent procedures are followed, apical periodontitis may still persist as asymptomatic radiolucencies, because of the complexity of the root canal system formed by the main and accessory canals, their ramifications and anastomoses where residual infection can persist. Further, there are extraradicular factors -- located within the inflamed periapical tissue -- that can interfere with post-treatment healing of apical periodontitis. The causes of apical periodontitis persisting after root canal treatment have not been well characterized. During the 1990s, a series of investigations have shown that there are six biological factors that lead to asymptomatic radiolucencies persisting after root canal treatment. These are: (i) intraradicular infection persisting in the complex apical root canal system; (ii) extraradicular infection, generally in the form of periapical actinomycosis; (iii) extruded root canal filling or other exogenous materials that cause a foreign body reaction; (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues; (v) true cystic lesions, and (vi) scar tissue healing of the lesion. This article provides a comprehensive overview of the causative factors of non-resolving periapical lesions that are seen as asymptomatic radiolucencies post-treatment.
根尖周炎是一种由牙髓源性病因引起的根尖周组织慢性炎症性疾病。当根尖周炎的根管治疗未能充分消除根管内感染时，就会发生持续性根尖周炎。导致持续性根尖周炎的问题包括：无菌控制不充分、开髓腔设计不佳、遗漏根管、器械操作不充分、清创不彻底以及临时或永久修复体渗漏。即使遵循了最严格的操作程序，根尖周炎仍可能以无症状性透射影的形式持续存在，这是因为主根管和副根管形成的根管系统及其分支和吻合处结构复杂，残余感染可能持续存在。此外，存在位于根尖周炎症组织内的根尖外因素，可干扰根尖周炎治疗后的愈合。根管治疗后根尖周炎持续存在的原因尚未得到充分阐明。在20世纪90年代，一系列研究表明，有六个生物学因素可导致根管治疗后无症状性透射影持续存在。这些因素包括：（i）复杂根尖根管系统中持续存在的根管内感染；（ii）根尖外感染，通常表现为根尖放线菌病；（iii）根管充填材料挤出或其他引起异物反应的外源性物质；（iv）刺激根尖周组织的内源性胆固醇晶体堆积；（v）真性囊性病变；（vi）病变的瘢痕组织愈合。本文全面概述了根管治疗后表现为无症状性透射影的未愈根尖周病变的致病因素。
