الفهرس 
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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
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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
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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%
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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
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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).