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Objective: To investigate the distribution of fimA and kgp genotypes as well as the common genotype combination of Porphyromonas gingivalis (Pg) in infected root canals of primary apical periodontitis for virulent isolates screening in future. Methods: Thirty-four samples harboring Pg were selected from infected root canals of primary apical periodontitis from patients of the Department of Endodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from June 2013 to September 2015. FimA type-specific primers were used to amplify the samples, revealing the distribution of various fimA genotypes. The genotypes of kgp were obtained by using Mse Ⅰ restriction endonuclease. The prevalence of each genotype and common genotype combinations were then calculated. Pearson's chi -squared test was performed to analyze the correlation between genotype combinations and clinical symptoms and major signs of apical periodontitis. In addition, the bioflim architectures between Pg isolates with different fimA and kgp genotype combinations were observed compared using confocal laser scanning microscope. Results: Among the 34 Pg-positive samples, fimA Ⅱ was the most prevalent genotype [47% (16/34)] followed by fimA Ⅰ [26% (9/34)], while fimA Ⅴ was detected in only one sample. The prevalence of kgp Ⅰ [56% (19/34)] was slightly higher than that of kgp Ⅱ [44% (15/34)]. Both fimA Ⅱ+kgp Ⅰ and fimAⅡ+kgp Ⅱ were the most prevalent genotype combinations [24% (8/34) each]. No significant correlation was found between specific genotype combination and such major clinical manifestations as gingival swelling and sinus tract of dental origin ( P> 0.05). Three Pg isolates with different genotype combinations were acquired. Isolate A (fimAⅠ+kgpⅠ) formed densest biofilm, while the biofilm of isolate C (fimAⅤ+kgp Ⅰ) was much looser. The biofilm feature of isolate B (fimAⅢ+kgp Ⅱ) fell in between A and C. Conclusions: Pg with fimA Ⅱ was most frequently detected in infected root canals of primary apical periodontitis. The prevalence of Pg with kgp Ⅰ was slightly higher than that with kgp Ⅱ, and fimAⅡ+kgp Ⅰ as well as fimA Ⅱ+kgp Ⅱ were the commonest genotype combinations. According to the comparison of Pg biofilms formed by clinical isolates, it might be possible that different genotype combinations may lead to distinct biofilm architectures.

Purpose: To detect the expression of suppressor of cytokine signaling-1 (SOCS-1) and suppressor of cytokine signaling-3 (SOCS-3) in chronic periapical lesions and to clarify their roles in pathogenesis of apical periodontitis., Methods: A total of 25 chronic periapical lesion tissues and 16 normal periodontal ligament tissues were collected respectively. The expression of mRNA was measured by real-time PCR, the protein expression was measured by immunohistochemical analysis. Statistical analysis was performed using SPSS 13.0 software package., Results: Immunohistochemical results indicated that expression levels of SOCS-1 and SOCS-3 protein in chronic periapical lesions were significantly higher than that in normal tissues (P<0.01); Moreover, SOCS-1 and SOCS-3 protein expression levels in severe inflammation group were significantly higher than that in mild inflammation group (P<0.01). In mild inflammation group, severe inflammation group and control group, the expression levels of SOCS-1 mRNA were 2.620±1.552, 2.373±1.083 and 1.277±1.040, whereas those of SOCS-3 were 9.308±5.901, 7.565±3.233 and 1.232±1.099, respectively., Conclusions: The expression levels of SOCS-1 mRNA and SOCS-3 mRNA are significantly higher both in mild inflammation group and severe inflammation group than that in control group (P<0.01), while no significant difference is found in mild and severe inflammation group.

Purpose: To observe the expression of IL-34 mRNA in chronic periapical lesions and healthy periodontal ligaments and discuss the role of IL-34 in the etiology of chronic apical periodontitis., Methods: A total of 25 periapical tissues from chronic apical periodontitis and 22 normal periodontal ligament tissue from extracted healthy teeth for orthodontic reason were selected. The expression of IL-34mRNA was detected by real-time PCR; the expression of IL-34 protein was detected by immunohistochemical analysis. Statistical analysis was performed using SPSS 13.0 software package., Results: The level of IL-34 mRNA expression in periapical lesions (3.53±3.07) was significantly higher than that of the normal control (1.07±0.76); IL-34 was positively expressed in lymphocytes, plasma cells and macrophages. Image analysis software indicated that the level of IL-34 protein was significantly higher in periapical lesions than that in normal control (P<0.01)., Conclusions: IL-34 may be closely related to inflammation of chronic apical periodontitis.

Purpose: To detect the expression of Wnt5a in lesions of chronic apical periodontitis and determine the relationship between expression of Wnt5a and inflammation degree., Methods: Ten patients with chronic apical periodontitis and 5 healthy controls were enrolled in this study. According to the inflammatory cell infiltration, the specimens were divided into 2 groups: severe inflammation group and mild inflammation group. The expression of Wnt5a was measured by real-time PCR (RT-PCR) and immunohistochemical analysis in the lesions of chronic apical periodontitis. The amount of Wnt5 expression was assayed and compared in different inflammation levels. Statistical analysis was performed using SPSS 13.0 software package., Results: Wnt5a was detected in both groups. Expression of Wnt5a mRNA in patients were significantly higher than the controls (P<0.05). According to inflammation level, the positive expression rate of Wnt5a in severe inflammation group was significantly higher than the controls (P<0.01), and Wnt5a positive expression in mild inflammation group was also significantly higher than the controls (P<0.05). The expression of Wnt5a was significantly different between severe inflammation group and mild inflammation group (P<0.05)., Conclusions: The expression of Wnt5a increases as the severity of tissue inflammation increases, which indicates that Wnt5a plays an important role in the development of chronic apical periodontitis.

Objective: To examine the expression of interleukin-17F (IL-17F) in apical periodontitis lesions., Methods: Human apical periodontitis lesions were collected after periapical surgery from November 1, 2009 to August 1, 2011. After histological processing, serial sectioning, HE staining, and microscopic analysis, 33 periapical cysts and 18 periapical granulomas were selected for immunohistochemical analysis for IL-17F. Five alveolar bone samples were obtained from a group of impacted third molars recommended for extraction. These bone samples did not show any inflammation and were used as normal samples. Differences in IL-17F expression between the tissues with periapical cyst and periapica granuloma were subsequently analyzed by rank-sum test., Results: IL-17F was expressed in epithelial cells, lymphocytes, fibroblast and endothelial cells of both types of lesions. Both types of lesions presented increased IL-17F expression when compared to healthy periapical alveolar bone. The expression of IL-17F in apical cyst (0.2365 ± 0.0708) and apical granuloma (0.8852 ± 0.0576) was significantly different (Z = 3.735, P < 0.01)., Conclusions: IL-17F could be observed and might be involved in the inflammatory response and bone resorption of periapical tissues. The expression of IL-17F in periapical cyst and periapical granuloma was significantly different.

Objective: To investigate the expression of key mediators that regulate bone resorption, receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in human periapical granuloma (PG) and radicular cyst (RC) characterized by periapical bone destruction., Methods: Immunohistochemical technique was performed using monoclonal antibody to detect RANKL and OPG expression in PG (n= 20 ) and RC (n= 20 ). As control group, healthy periodontal ligament tissues (n = 6 ) were obtained from teeth with orthodontic indication of extraction., Results: The RANKL protein expression was significantly higher in PG (43.74 +/- 8.40) and RC (40.33 +/- 7.53) than in control group (15.47 +/- 2.59, P=0.000) , but no statistical significance could be found between PG and RC groups(P=0.161) .The expression of OPG in PG (27.81 +/- 5.17), RC (26.35 +/- 3.86) and control group (24.33 +/- 3.50) show no statistical significance (P >0.05). Moreover, RANKL/OPG ratio in PG (1.59 +/- 0.26) and RC (1.54 +/- 0.24) was much higher than that in control group (0.64 +/- 0.10, P=0.000), however the ratio of RANKL/OPG showed no significant difference between PG and RC groups (P= 0.504) ., Conclusion: RANKL and OPG were observed in the periapical lesions. RANKL may be responsible for bone resorption in periapical lesions. RANKL and OPG may play an important role in the development of periapical lesions.

Objective: To quantify COX-2 mRNA in lesions of chronic apical periodontitis and relate the findings to the histological findings., Methods: A total of 13 periapical lesions including 10 periapical granulomas and 3 periapical cysts were obtained. Normal periodontal ligament tissues from extracted third molars were used as control tissues. The expression of COX-2 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) technique. The relationships between the expression of COX-2 mRNA and histological findings (including the type of histology, the degree of inflammatory infiltrates), the size of radiolucent of the lesions and the clinical findings of the involved tissues were analyzed. The expression of COX-2 at cell level was detected by immunohistochemistry., Results: A significant higher level of COX-2 mRNA was found in periapical granulomas and in periapical cysts , but no significant difference was detected between those two groups. COX-2 mRNA in the group with moderate inflammation cell infiltration was higher than that of light and heavy inflammation cell infiltration (0.76+/-0.11 vs 0.11+/-0.01, 0.76+/-0.11 vs 0.23+/-0.06, P<0.05). The elevated COX-2 mRNA levels were detected in lesions with clinical symptoms. COX-2 -positive cells were detected in the epithelial cells and inflammatory cells., Conclusion: COX-2 might play more important roles in the pathogenesis and development of periapical lesions.

Purpose: To evaluate the relationship between IL-1beta and clinical findings of chronic apical periodontitis and to explore the function of IL-1beta during the endodontic interappointment flare-ups., Methods: Periapical exudates samples were obtained from 19 teeth suffering from endodontic flare-ups after root canal preparation and 20 teeth without any symptoms and signs at the second visit after root canal preparation. The levels of IL-1beta were determined by ELISA and the data was analyzed by SAS6.12 software package., Results: Significantly higher levels of IL-1beta were found in periapical exudates from teeth suffering from endodontic flare-ups than that before canal preparation(P<0.001). The mean IL-1beta levels significantly decreased following the endodontic therapy if there were no symptom at the second visit (P<0.001)., Conclusion: The level of IL-1beta in the exudates of root canals were related with the exist of infection which might take an active part in the occurrence of endodontic interappointment flare-up.

Objective: To characterize the expression of lipopolysaccharide (LPS) receptors-CD14 and TLR4 in rat peri-radicular tissue and to investigate the signal transduction pathway of LPS and its receptors in periapical periodontitis., Methods: After establishment of a model of rat molar LPS-induced apical periodontitis, CD14 and TLR4 expression in healthy and inflammatory periapical tissue were determined by immunohistochemistry., Results: CD14 and TLR4 were not detected in healthy periapical tissue but strongly positive in inflammatory periapical tissue. Positive cells were mostly monocytes/macrophages., Conclusions: CD14 and TLR4 may play an important role in the pathogenesis of periapical periodontitis, probably via immune cells such as monocytes/macrophages and neutrophils.

Objective: To compare the endotoxin levels between acute and chronic periapical periodontitis with different clinical symptoms., Methods: 10 cases of acute periapical priodontitis(Group 1), 10 cases of chronic periapical periodontitis (group 2, the diameter of apical radiolucency area was less than 2 mm), 10 cases of chronic periapical periodontitis with sinus(group 3, the diameter of apical radiolucency area was greater than 2 mm), 10 cases of chronic periapical periodontitis without sinus (group 4, the diameter of apical radiolucency area was greater than 2 mm), were included in the study. Chromogenic substrate method of limulus amebocyte lysate(LAL) test was used to measure the endotoxin level., Results: Endotoxin concentrations in group 2 were significantly lower than those in group 1, group 3 and group 4(P < 0.01)., Conclusion: Endotoxin plays a very important role in the initiation and development of periapical periodotitis and is closely associated with clinical symptoms and apical radiolucency degree.

Objective: The aim of this study was to examine the levels of prostaglandin E2 in periapical exudates before and after root canal treatment., Methods: Periapical exudates specimens were quantitatively sampled from root canals of 25 teeth at consecutive treatment visits, and the concentration of prostaglandin E2 in each sample was determined using a commercial kit., Results: The mean prostaglandin E2 levels significantly decreased after the endodontic therapy. Significant correlations between the levels of prostaglandin E2 and the clinical features of periapical periodontitis were also found in this study., Conclusion: The results suggest that the level of prostaglandin E2 in periapical exudates reflects the state of periapical periodontitis.

Objective: To further study the mechanisms of damages and resorption of bone in chronic periapical periodontitis., Methods: The quantities and distribution of PGE2 and TXB2 in apical granuloma of chronic periapical periodontitis were analyzed using radio immunization analysis., Results: The quantities of PGE2 and TXB2 in apical granuloma of chronic periapical periodontitis were significantly (P < 0.05) higher than those in controls., Conclusion: The PGE2 has the close relation with the bone resorption of chronic periapical periodontitis during the whole process. Meanwhile, TXB2 also has certain relation with the bond absorption. The quantities of PGE2 and TXB2 are imbalanced.