الفهرس 
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Abstract
Summary and Conclusions
The aim of this study was to compare the effect of two different
methods of sterilization which are steam under pressure and gamma
radiation on the surface topography of different endodontic files and also to
determine the efficiency of both methods in killing different pathogens.
The current study included 140 endodontic files (70 Ni-Ti and70
stainless steel files). Sixty files (30 Ni-Ti and 30 St.St) were used to compare
the effect of the two different methods of sterilization on their surface
topography using different number of cycles. The number of cycles used
was 5 cycles and 10 cycles. The study was conducted on K3 files which are
Nickel titanium files and K files which are the stainless steel files.
The files that have been sterilized with the different number of cycles
have been subjected to surface topography examination using scanning
electron microscope and using the SEM pictures the level of roughness
(surface topography) was rated and scored from level zero to level 3.
The data obtained were collected, tabulated and statistically analyzed.
Results of this study showed that:
Results of this study showed that when comparing between the two
different methods of sterilization used there was no statistically significant
difference in surface imperfections observed on both stainless steel and
nickel titanium instruments after five or ten sterilization cycles using either
steam under pressure (autoclave) or gamma radiation. (P>0.05)
Both methods of sterilization caused an alteration in surface
imperfections of the files after 5 and 10 cycles but these changes were not
statistically significant.
Regarding the efficiency of sterilization methods used in this study,
results showed that both methods; steam under pressure and gamma
radiation were successful in eradicating all micro-organisms.
Within the limitations of this study, it can be concluded that:
1. Steam under pressure and gamma radiation were reliable and verifiable
methods for sterilization of endodontic instruments
2. Steam under pressure and gamma radiation didn’t adversely affect surface
topography of nickel titanium and stainless steel endodontic instruments up
to ten cycles.