OBJECTIVES To compare the microbial load and composition and to determine the lipopolysaccharides (LPS) and lipoteichoic acid (LTA) concentrations found in primary apical periodontitis (PAP) and post-treatment apical periodontitis (PTAP), correlating these findings with clinical/tomographic features. MATERIAL AND METHODS Sixty patients with PAP (31) and PTAP (29) were submitted to clinical and tomographic assessment. Samples were collected from each root canal using paper points for microbiological assessment (culture technique and Checkerboard DNA-DNA hybridization) and determination of LPS and LTA levels (limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively). Data were correlated with clinical/tomographic findings and statistically analyzed using the Mann-Whitney and Pearson correlation tests (α = 5%). RESULTS A higher number of cultivable bacteria and LPS were found in PAP (p < 0.05). The median number of species per root canal found in PAP and PTAP was 9 and 22, respectively (p < 0.05). LPS was positively correlated with a larger periapical lesion volume (p < .05). LTA levels were similar in both infections and had no correlation with signs and symptoms. In PAP, gram-positive bacteria were correlated with spontaneous pain (p < .05) and exudate (p < .05). Tenderness to percussion and pain on palpation were correlated to the presence of both gram-positive and negative bacteria. In PTAP, a positive correlation was observed between both gram-positive and gram-negative bacteria with exudate and periapical lesion volume (p < .05). CONCLUSIONS PAP had higher contents of microbial load and LPS compared with PTAP. However, PTAP presented a more diverse microbiota compared with PAP. Higher content of LPS was positively correlated with larger periapical bone destruction, whereas signs and symptoms with specific microorganisms. CLINICAL RELEVANCE It was verified that PAP and PTAP are polymicrobial infections with predominance of gram-negative bacteria and a more diverse bacterial population found in PTAP. A wide interaction of specific microbial species resulted in different clinical features in both infections.

中文翻译：

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原发性与治疗后的根尖性牙周炎：微生物组成，脂多糖和脂蛋白酸水平，体征和症状。

目的比较原发性根尖周炎（PAP）和治疗后根尖周炎（PTAP）中发现的微生物负荷和组成并确定脂多糖（LPS）和脂蛋白酸（LTA）的浓度，并将这些发现与临床/断层扫描特征联系起来。材料与方法60例PAP（31）和PTAP（29）患者接受了临床和X线断层检查。使用纸质点从每个根管收集样品，以进行微生物学评估（培养技术和Checkerboard DNA-DNA杂交），并确定LPS和LTA水平（分别是lim变形细胞溶解物和酶联免疫吸附法）。数据与临床/断层扫描结果相关联，并使用Mann-Whitney和Pearson相关检验进行统计分析（α= 5％）。结果在PAP中发现了更多的可培养细菌和LPS（p <0.05）。在PAP和PTAP中发现的每根根管物种数的中位数分别为9和22（p <0.05）。LPS与较大的根尖周病变体积呈正相关（p <.05）。两种感染的LTA水平相似，并且与体征和症状无相关性。在PAP中，革兰氏阳性细菌与自发性疼痛（p <.05）和渗出液（p <.05）相关。触诊时的压痛和疼痛的柔韧性与革兰氏阳性和阴性细菌的存在有关。在PTAP中，革兰氏阳性菌和革兰氏阴性菌与渗出液和根尖周病变体积之间均呈正相关（p <.05）。结论与PTAP相比，PAP具有更高的微生物负荷和LPS含量。然而，与PAP相比，PTAP呈现出更多样化的微生物群。LPS的较高含量与更大的根尖周骨破坏呈正相关，而特定微生物的体征和症状则与之相关。临床相关性已证实，PAP和PTAP是多菌感染，以革兰氏阴性菌为主，并且在PTAP中发现的细菌种群更多。特定微生物种类的广泛相互作用导致两种感染的临床特征不同。临床相关性已证实，PAP和PTAP是多菌感染，以革兰氏阴性菌为主，并且在PTAP中发现的细菌种群更多。特定微生物种类的广泛相互作用导致两种感染的临床特征不同。临床相关性已证实，PAP和PTAP是多菌感染，以革兰氏阴性菌为主，并且在PTAP中发现的细菌种群更多。特定微生物种类的广泛相互作用导致两种感染的临床特征不同。