OBJECTIVEThis study aims to develop and observe a model system of the periapical biofilm structure of Enterococcus faecalis (E. faecalis).

METHODSA total of 24 intact human single-rooted premolars extracted for orthodontic reasons were collected and randomly divided into eight groups (n = 3). The specimens were subjected to ultraviolet disinfection, inoculated with E. faecalis (ATCC 29212) suspension adjusted to 1 x 10(8) CFU x mL(-1), and incubated at 37 degrees C for 1, 2, and 7 d. Specimen groups were prepared for scanning electron microscope to examine the biofilm formation. The specimens in the confocal laser scanning microscope (CLSM) groups were stained with propidium iodide (PI) and ConA-fluorescein isothiocyanate (ConA-FITC) to examine the biofilm formation. The images were randomized, and biofilm coverage (%) was assessed using Photoshop CS5.

RESULTSThe biofilm coverage (%) on the cementum increased with increasing incubation period. The biofilm coverage of the 7 d group was significantly higher than those of the 1 and 2 d groups (P < 0.05). The values of the latter two groups were not significantly different (P > 0.05). Dense aggregations composed of E. faecalis and the amorphous matrix were observed on the root cementum surfaces of the specimens in the 7 d group. The bacteria were stained red by PI, and the matrix was stained green by ConA-FITC under CLSM observation. The biofilm coverage (%) on the samples in the 7 d group was 17.23% +/- 1.52%, showing multi-level space structure and water channels.

CONCLUSIONE. faecalis forms bacterial biofilms on the root cementum surface in 7 d. The biofilms were composed of E. faecalis and the amorphous matrix.

OBJECTIVEThis study aims to evaluate the shaping capability of Reciproc, WaveOne, Mtwo, and ProTaper instruments in simulated root canals.

METHODSA total of 40 simulated resin blocks were divided randomly into four groups. Each group was prepared with Reciproc (Group 1), WaveOne (Group 2), Mtwo (Group 3), and ProTaper (Group 4). The preparation time and reduction in working length after preparation were measured. Pre- and post-operative images were obtained with a scanner and superimposed through Photoshop. The changes in canal curvature and material removal from the inner and outer canal walls at 10 points beginning at 1 mm from the end point of the canal were measured with Image J. Centering capability was determined accordingly. Data were analyzed through one-way ANOVA, SNK, and Kruskal-Wallis at a significance level of P < 0.05.

RESULTSThe preparation time of Group 2 was (53.7 ± 6.7) s, whereas those of Groups 1, 3, and 4 were (86.9 ± 8.1) s, (112.2 ± 8.2) s, and (177.9 ± 11.2) s, respectively; the difference was found to be significant (P < 0.05). The reductions in working length among the four groups after preparation were not significantly different (P > 0.05). The canal curvature for Groups 1 to 4 were 2.671° ± 0.637°, 2.667° ± 0.450°, 3.664° ± 0.870°, and 3.797° ± 0.601°, respectively. The changes for Groups 1 and 2 were significantly smaller than those for Groups 3 and 4. At the 3 mm point, the transportation of Group 1 was (-0.016 ± 0.094) mm, which was significantly less than that of the other instruments (P<0.05). At the 4 mm and 5 mm points, the trans- portation values of Group 2 were (-0.080 ± 0.104) mm and (-0.312 ± 0.088) mm, which were significantly less than that of Group 1 [(-0.243 ± 0.099) mm, (-0.404 ± 0.064) mm, P < 0.05].

CONCLUSIONReciproc and WaveOne can complete preparation faster and can maintain the original canal curvature better than Mtwo and ProTaper. Reciproc exhibits superior centering capability in the apical part of the canal, whereas WaveOne exhibits superior centering capability in the middle part of the canal.

Objective:To observe the effect of soluble CD14 (sCD14) on the inducing activity of lipopolysaccharide(LPS) on human gingival fibroblasts(HGFs). Methods:In vitro cultured HGFs were stimulated by FITC labeled LPS at the concentration of 0 (control), 100 ng/ml, 100 ng/ml LPS+100 ?g/ml sCD14 and 100 ng/ml LPS+100 ?g/ml ENP respectively for 24 h. The binding activity of LPS to HGFs was measured in the level of mean fluorescence intensity of FITC-LPS.TNF-? and IL-6 in the culture supernatant were measured by ELISA. Results:The binding activity of FITC-LPS to HGFs and the level of TNF-? and IL-6 in culture supernatant were significantly decreased in sCD14 and ENP group(P

Objective:To evaluate the prevalence of Pe in clinical samples of chronic periapical periodontitis.Methods:A total of 100 clinical samples of chronic periapical periodontitis were collected and Pe 16S rDNA was detected by using 16S rDNA gene-directed PCR.The detection rate of Pe were calculated.Results:The detection rate of Pe was 50% in the 100 clinical samples.Conclusion:The results indicate that Pe is closely associated with endodontic infections.

Objective: To evaluate effect of the morphology of simulated S-shaped root canals with Reciproc or Mtwo instruments on root canal irrigation. Methods: A total of 40 simulated S-shaped resin blocks were randomly divided into 2 groups (n=20), which was prepared by Reciproc or Mtwo. Blue ink was injected with constant speed and volume into the canals using 30G lateral opening syringe. hTe distance from needle tip to apex and vapor lock length were measured. A type of 25# 0.04 gutta-percha point was used to stir and remove the vapor lock. hTe time for removal of the vapor lock was recorded. Another syringe was used to inject saline into the canals and to measure the length of stagnant water. Results: hTe distance from needle tip to apex in the Reciproc group was signiifcantly longer than that in the Mtwo group [(4.276 ± 0.221) mm vs (3.459 ± 0.205) mm,P<0.05]. The vapor lock length in the Reciproc group was signiifcantly longer than that in the Mtwo group [(4.472 ± 0.230) mm vs (3.668±0.217) mm,P<0.05]. hTe time to remove vapor lock was signiifcantly shorter in the Reciproc group than that in the Mtwo group [(10.13 ± 1.79) s vs (15.29 ± 2.15) s,P<0.05]. The length of stagnant water was also shorter in the Reciproc group than that in the Mtwo group[(1.351 ± 0.142) mm vs (2.245 ± 0.206) mm,P<0.05]. Conclusion: hTe morphology of S-shaped root canal affects the root canal irrigation. hTe effect of root canal irrigated by Reciproc is better than that by Mtwo.

Objective To investigate the influence of ultrasonic cleaning time and disinfecting frequency on physical property of Ni-Ti root canal files in order to understand the safety and feasibility of ultrasonic cleaning and high temperature and high pressure disinfection for Ni-Ti root canal files.Methods The Ni-Ti root canal files used in this study were ProTaper,Mtwo and Hero642,5 files were selected from each kind.After the ultrasonic cleaning and high temperature high pressure disinfection the files underwent breaking test,the breaking time was recorded.Unclean and non-sterile Ni-Ti root canal files were set as control.Results After different time of ultrasonic cleaning,ProTaper and Mtwo showed no difference in breaking time,but the result was opposite in Hero642.After different times of disinfection,Mtwo showed no difference in breaking time,but significant difference was seen in the other two kinds.Conclusions Ultrasonic cleaning time has no significant influence on physical property of ProTaper and Mtwo Ni- Ti root canal files,but the influence was significant for Hero642.Disinfection frequency had no significant influence on physical property of ProTaper and Hero642 Ni-Ti root canal files,but the influence was significant for Mtwo Ni-Ti root canal files.

Objective:To evaluate the effects of different growth conditions on E.faecalis growth in the microfluid chip and the penetration of E.faecalis into microtubes.Methods:Four units on the chip were randomly selected as control,BHI,nutrient-Tdeprived (PBS) and pH 10 groups.The growth of E.faecalis was monitored by microscope for a period of 72 h after the suspension of E.faecalis had been added into the chip.Results:The microscopic analysis showed a distinct variation in the growth rate and morphological feature under different experimental conditions.he depth of bacterial penetration was significantly greater in BHI group.Conclusion:This study demonstrated that environmental changes can significantly influence the growth and penetration of E.faecalis into the micro tubes.

OBJECTIVEThis study aims to assess and compare the prevalence of Porphyromonas endodontalis (P. endodontalis) in root canals associated with primary and secondary endodontic infections by using 16s rDNA PCR and real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR).

METHODSA total of 120 adult patients with one radiographically documented periapical lesion were included. Sixty teeth presented with primary endodontic infections and 60 with secondary endodontic infections requiring retreatment. P. endodontalis was identified by using 16s rDNA PCR techniques. The positive DNA expression of P. endodontalis in two types of infected root canals were quantitatively compared by using SYBR GREEN I RTFQ-PCR.

RESULTSThe prevalence of P. endodontalis in the root canals with primary endodontic infections was significantly higher than that in root canals with secondary endodontic infections (P = 0.001). However, RTFQ-PCR results showed no significant difference in DNA expression quantities between the primary and secondary endodontic infections root canals (P = 0.303).

CONCLUSIONP. endodontalis is more highly associated with root canals having primary endodontic infections, although P. endodontalis colonize in both root canals with primary and secondary chronic apical periodontitis.

BACKGROUND:More recently, the focus has been on searching for a compound Chinese medicine for reinforcing kidney, which cannot only inhibit bone absorption, but also promote osteogenesis to protect against osteoporosis. OBJECTIVE:To explore effects of drug serum of Jianbuhuqian pil s on proliferation and function of osteoblast-like cel s in vitro. METHODS:Twenty-four adult female Sprague-Dawley rats were randomly divided into low-dose, medium-dose, high-dose and normal saline groups, and given intragastric administration of 1.5, 3.0, and 6 g/kg Jianbuhuqian pills and equal volume of normal saline, respectively twice daily for 1 week. At 1 hour after final gavage, rats were decapitated to prepare drug sera used for culturing osteoblast-like cells. At 24, 48 and 72 hours of culture, the cellular morphology was observed, as well as the cell proliferation and alkaline phosphatase activity was detected by MTT assay and alkaline phosphatase staining, respectively. RESULTS AND CONCLUSION:Compared with the normal saline group, the cel density began to increase significantly in three Jianbuhuqian groups at 24 hours after culture, mitotic figures were easy to be observed, cel s were in overlapping growth, much secretions and matrix accumulation appeared, especial y in the high-dose group. The obsorbance values in Jianbuhuqian groups were significantly higher than that in the normal saline group. After 24 hours of culture, the obsorbance values in the medium-dose and high-dose groups were significantly increased compared with the low-dose group, and the values showed significant differences among three Jianbuhuqian groups after 48 and 72-hour culture. In addition, the alkaline phosphatase activity presented overt increase in the Jianbuhuqian groups compared with the normal saline group, and significant differences could be found among Jianbuhuqian groups. To conclude, the drug serum of Jianbuhuqian pil s can promote the activity of osteoblast-like cel s in a time-and concentration-dependent manner.

The excellent magnification and illumination of the operating microscope not only helps to improve the quality of conventional root canal therapy, but also plays an important role in the diagnosis and treatment of the difficult cases of endodontic diseases. It has an irreplaceable position over other equipment especially for the treatment of root canal therapy complications and the apical surgery. The structure and operation of the operating microscope are relatively complicated. The proficiency of the dentist may influence the evaluation of its clinical application effect. Based on the review of literature and author's clinical experience, this paper evaluates the role of operating microscope in the diagnosis and treatment of endodontic diseases.