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Abstract The aim of the present study was to evaluate the effect of tip diameter and file motion on bacterial reduction during cleaning and shaping using One shape (rotary system) sizes (25/0.06), (37/0.06) and Wave one (reciprocating system) sizes(25/0.08), (40/0.08) by the aid of direct count of colony forming units (CFUs). Sixty single rooted lower premolars freshly extracted human permanent teeth were selected for this study. The teeth were decoronated using a high speed diamond stone with water coolant and the root length was standardized at length of 15mm. Access into the canals was done and working length of the canal was determined visually by inserting a #15 stainless steel k-file until the file tip was visible at the apical foramen under 4X magnification loupe, and the working length (WL) was established 1 mm short of this length. Irrigation was performed using 2.5% NaOCl irrigation, and then was washed with 5mL of saline solution. Then, the teeth were sterilized in autoclave for 15 min at 121 °C. Then the roots were coated with nail polish. The E. faecalis was inoculated at 37°C for 24 hours and resuspended in saline to reach a final concentration of 3X108 cells/ml, and adjusted to No.1 macFarland turbidity Summary&Conclusion 96 standard. The samples were contaminated with a 3ml of bacterial suspension and fresh bacterial suspension was prepared and replaced every 72-hours for a period of three weeks, then a random specimen from each subgroup were cultured using sterile paper point to confirm the contamination with the bacteria. The samples were divided into 3 groups of 20 teeth, and each group has 2 subgroups (n=10). Each root canal was filled with sterile saline and A sterile paper point were placed in the root canal as close to the working length as possible Each sample was homogenized by vortexing for 30 seconds. Serial 10-fold dilution (1:10, 1:100 and 1:1000) was made in saline. Then 0.1 mm from each dilution was smeared to be inoculated on surface of the plate media (BHI agar plates), incubated at 37°C for 24 hours, and CFU per 1 ml was calculated, where the mean value of the bacterial count found to be (23.7×10×103 ± 4.4×10×103). group A: Cleaning and shaping was done with the one shape NiTi rotary file The operating sequence was as follows: a size #15 K file and the canal was irrigated by using 5 ml of 2.5% NaOCl then Endoflare and the canal was irrigated by using 5 ml of 2.5% NaOCl then, One Shape NiTi Summary&Conclusion 97 instrument was used gently using in and out pecking movements without pressure until reaching the working length. The instrument was removed and the canal was irrigated by using 5ml of 2.5% NaOCl. Specimens in Subgroup A1 (n = 10) were prepared with One Shape file size (25/0.06). Specimens in Subgroup A2 (n = 10) were prepared with One Shape file size (37/0.06). group B: Cleaning and shaping was done with the Wave One Niti reciprocating file. The operating sequence was as follows: a size #15 K file and the canal was irrigated by using 5 ml of 2.5% NaOCl then Endoflare and the canal was irrigated by using 5 ml of 2.5% NaOCl then, Wave one was used gently in a brushing motion until reaching the working length and the canal was irrigated by using 5ml of 2.5% NaOCl. Specimens in Subgroup B1 (n = 10) were prepared with Wave One file size (25/0.08). Specimens in Subgroup B2 (n = 10) will be prepared with Wave One file size (40/0.08). After preparation was complete, the canal was rinsed with 5 mL of 17% EDTA, followed by 5 mL of 2.5% Summary&Conclusion 98 NaOCl each left in the canal for one min followed by final flushing using 5 mL 0.9%saline to eliminate the irrigation solutions from the root canal. 2.5% NaOCl was used as the main irrigant, with a total volume of 20 mL per canal. The average total time that NaOCl remained in the canal in each group was about 10min. group C: In the control Subgroup C1 (n=10) canals were irrigated with 20 mL of a 2.5% NaOCl solution without instrumentation after pulp extirpation using sterile file # 15. The average total time that NaOCl remained in the canal was about 10 min. In the control Subgroup C2 (n=10) canals were not instrumented or irrigated only pulp will be extirpated using sterile # 15 File. At the end of the procedure, the samples were flushed with 5ml saline, then #15 K-file was placed into the canal to within 1 mm of working length and circumferentially filed for 10 seconds before sterile absorbent paper points adsorbed the transport fluid and transferred to a test tube containing 1ml saline. Each sample was homogenized by vortexing for 30 seconds. Serial 10-fold dilution (1:10, 1:100 and 1:1000) was made in saline. Then 0.1 mm from Summary&Conclusion 99 each dilution was smeared to be inoculated on surface of the plate media (BHI agar plates), incubated at 37°C for 48 hours, and colony-forming units (CFU) per 1 ml were enumerated. The result of this study showed that: 1- There was statistically significant difference comparing percentage of bacterial reduction of both C1 and C2 to both A1 and A2. 2- There was statistically significant difference comparing percentage of bacterial reduction of both C1 and C2 to both B1 and B2. 3- There was statistically in-significant difference between One shape file size 25(Subgroup A1) and One shape file size 37(Subgroup A2). 4- A statistically significant difference found between Wave one file size 25(Subgroup B1) and Wave one file size 40 (Subgroup B2). 5- Wave One reciprocating files sizes (25,40) are more effective in bacterial reduction than One Shape rotating files sizes (25, 37). |