الفهرس 
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Abstract
The purpose of the present in vitro study was twofold: First, to evaluate the effect of cleaning and shaping on the elimination of bacteria of infected root canal using two different rotary files; WaveOne (reciprocating file) and Revo S (rotational file) Second, to evaluate the influence of obturation on the remaining bacteria utilizing epoxy resin based sealer (AH PLUS) and new MTA based sealer (MTA-Fillapex).
Materials and Methods:Ninety freshly extracted human single rooted maxillary teeth were collected for this study. The crowns of all teeth were resected with a high speed tapered fissure bur under air water spray provided that the total length of each root was standardized to be 17 mm in length. All samples were then sterilized in an autoclave for 20 mins at 121oC. Two layers of nail polish were applied to the external surfaces of all roots, leaving the apical 2 mm uncoated. Apical foramina were sealed with melted blue wax and 10 μl of E. faecalis suspension in Trypticase soy broth were applied into the canal of each sample.After seven days incubation period the wax of the coronal access was removed and the first bacteriological sample (S1) was taken, and the number of colony-forming units per milliliter (CFU/ml) was counted.Eighty samples were randomly divided into 2 groups according to the instrumentation technique, while ten samples were used as a control. 40
Summary and Conclusions-108-
root canals were instrumented using WaveOne reciprocating file (Group A) and 40 root canals were instrumented using Revo s rotary file (Group B). Sodium hypochlorite 2.5% was used as an irrigant in this study with total volume of 15 mL per canal. Immediately after the cleaning and shaping the second bacteriological sample (S2) was taken and data were recorded.After the second bacteriological sample was taken each root canal was filled with 20 μl sterile trypticase soy broth and the coronal access was sealed with melted blue wax and incubated at 37°C for seven days, then the third bacteriological sample (S3) of each root canal was taken and the number of CFU/ml was counted.The samples external surfaces were disinfected by 5 ml of 5.25% sodium hypochlorite solution and each sample was mounted and secured into the Eppendorf tubes. 30 teeth of each group A and B were subdivided into 2 subgroups; subgroups 1, root canals were obturated using gutta-percha and epoxy resin sealer (AH Plus), subgroups 2, root canals were obturated using gutta-percha and MTA based sealer (MTA Fillapex). Lateral condensation technique was used in obturation of all experimental samples. The remaining ten samples were equally divided into positive and negative control. The internal apical leakage of bacteria was then evaluated at designated periods; one week, one month, two months and three months.Summary and Conclusions-109- Results:
The results showed that there was no statistically significant difference between WaveOne (reciprocating file) and Revo S (rotational file). Both were significantly reduced the bacterial counts than the control group. One week after obturation, the increase in CFU was insignificantly different for both subgroups obturated with AH Plus & MTA Fillapex. Whereas, along the remaining studying periods, there was a significant increase in CFU for MTA Fillapex subgroup than that of AH Plus subgroup.