Endo Marcos S, Ferraz Caio C R, Zaia Alexandre A, Almeida Jose F A, Gomes Brenda P F A
Department of Restorative Dentistry, Endodontics Division, Piracicaba Dental School - State University of Campinas - UNICAMP, Piracicaba, SP, Brazil.
Eur J Dent. 2013 Jul;7(3):302-309. doi: 10.4103/1305-7456.115414.
The aim of this study was to investigate in vivo microorganisms detected in root-filled teeth with post-treatment apical periodontitis and quantify colony-forming units (CFU) during endodontic retreatment.
Fifteen root-filled teeth had their previous gutta-percha removed and were randomly instrumented before being divided into three groups and medicated with either [Ca(OH)2 + 2% CHX gel], [Ca(OH)2 + 0.9% NaCl] or 2% CHX gel. Samples were taken after removal of gutta-percha (S1), after chemomechanical preparation using 2% CHX gel (S2), and after inter-appointment dressing (S3) for 7 or 14 days later. Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of culture and PCR assay (16S rDNA). Quantitative data were statistically analyzed by using Mann-Whitney test in which pairs of groups were compared (P < 0.05).
CFU counts decreased significantly from S1 to S2 (P < 0.05). No significant difference was found between S2 and S3 (P = 0.3093) for all three experimental groups. Chemomechanical preparation and intra-canal dressing promoted significant median reductions of 99.61% and 99.57%, respectively, in the number of bacteria compared to S1 samples. A total of 110 cultivable isolates were recovered by culture technique from 32 different species and 7 different genera. Out of the 13 target species-specific primer of bacteria analyzed, 11 were detected during endodontic retreatment.
The great majority of taxa found in post-treatment samples were Gram-positive bacteria, although Gram-negative bacteria were found by molecular methods. Moreover, our results showed that gutta-percha removal and chemomechanical preparation are effective for root canal disinfection, whereas additional intra-canal dressing did not improve disinfection.
本研究旨在调查根管充填后患有根尖周炎的牙齿中体内检测到的微生物，并在根管再治疗期间对菌落形成单位（CFU）进行定量。
15颗根管充填牙去除先前的牙胶后随机进行预备，然后分为三组，分别用[氢氧化钙+2%氯己定凝胶]、[氢氧化钙+0.9%氯化钠]或2%氯己定凝胶进行药物处理。在去除牙胶后（S1）、使用2%氯己定凝胶进行化学机械预备后（S2）以及复诊换药后7天或14天（S3）采集样本。对三个阶段从感染根管中回收的可培养细菌进行计数，并通过培养和PCR检测（16S rDNA）进行鉴定。定量数据采用Mann-Whitney检验进行统计学分析，比较各组之间的差异（P<0.05）。
从S1到S2，CFU计数显著下降（P<0.05）。所有三个实验组在S2和S3之间均未发现显著差异（P = 0.3093）。与S1样本相比，化学机械预备和根管内换药分别使细菌数量中位数显著减少了99.61%和99.57%。通过培养技术从32个不同物种和7个不同属中总共回收了110株可培养分离株。在分析的13种细菌目标物种特异性引物中，有11种在根管再治疗期间被检测到。
尽管通过分子方法检测到了革兰氏阴性菌，但治疗后样本中发现的绝大多数分类群是革兰氏阳性菌。此外，我们的结果表明，去除牙胶和化学机械预备对根管消毒有效，而额外的根管内换药并未改善消毒效果。
