الفهرس 
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Abstract
Summary and Conclusion
The root canal treatment procedure aims to remove any remaining infected pulp tissues or necrotic debris and infected dentin from within the canal spaces. The introduction of rotary NiTi instruments facilitated the effectiveness and speed of cleaning and shaping procedure even in most severe canal curvature resulting in the establishment of a better prognosis helping in restoring the lost function, through a 3 dimensional cleaning and shaping of the canals, together with a 3 dimensional sealing of the canal system.
However, the complete removal of the microorganisms from within the canals is considered somehow difficult with the use of mechanical shaping only. As this mechanical shaping instruments will result in the production of a considerable amount of debris, and a tenaciously adherent amorphous structure known as the smear layer. This layer contains bacteria and their byproducts and particles of collagen matrix, compromising the final outcome of the treatment by creating flaws in the obturation. These flaws result from several factors that happened due to the incomplete removal of the previously mentioned debris and smear layer caused by the mechanical cutting of the infected dentin within the canal during the treatment process.
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These factors result from the inability of the irrigating materials and the intracanal medicaments to penetrate through the dentinal tubules and deeply clean and disinfect the surface and this is caused by the incomplete removal of the smear layer. The smear layer also compromises the bonding and the penetration of the sealers to the dentinal walls causing further percolation of fluids from the inflamed periapical tissues compromising the apical and the coronal seal, resulting in failure of the treatment.
The present study was designed to evaluate the amount of extruded debris and the cleaning ability after using different three full sequence rotary systems.
Forty five human lower central incisors with mature apices were used in this study. Samples was cleaned from any soft and/or hard calcareous deposits and then stored in saline solution until used.
Samples were divided into three groups, according to the rotary system used, each group included fifteen teeth was instrumented using different file system where group (1) was prepared using Endoplus gold files, group (2) was prepared using M-Pro files and group (3) prepared using ProTaper Universal files. For the first part of the study the collection of the apically extruded debris and evaluation was done according to the method described by Myers & Montgomery (1991), which were
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weighted before and after to detect the amount of the extruded debris.
Results showed that the mean amount of extruded debris was0.9554 ± 0.0145 gm for ProTaper group and 0.9381 ± 0.0476 for M-Pro group and 0.9520 ± 0.0160 gm for Endo plus gold group.
Statistical analysis showed that there was no significant difference between the three tested groups.
For the second part of the study the cleaning ability was evaluated using SEM where the acrylic block was ground from the labial aspect using a carborundum disc to make longitudinal groove and then similar longitudinal groove was done from lingual aspect. Gutta-percha master cone was placed in root canal before sectioning to prevent debris intrusion in the canal, finally the sectioning was done using chisel and mallet after making the grooves to prevent debris entering to the canal. The master cone was removed and a longitudinal section was obtained.
The cleaning efficiency was evaluated in terms of the amount of debris in the canal. The longitudinal sections were photographed using the scanning electron microscope after gold plating of each sample under 200x and 1000x. The debris and smear layer were evaluated according to the five point scoring system which was described before by Hülsmann et al (2007)
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Results showed that, In ProTaper group, apical region, 35.71% of samples recorded score 5 27.27% recorded score 3 and 28.57 recorded score 2. In the middle region it had the same percentage while for the coronal region 42.86% of score 3 and 32.46% of score 5.
The M-Pro group results showed 38% of score 3 for the apical region and 50% of score 4 for the middle region and 33.33% of score 3 for the coronal region.
The results for the Endo plus group showed 42.22% of score 4 for the apical region and 33.61% of score 3 for the middle region and 50% of score 4 for the coronal region.
Statistical analysis showed that there was no significant difference between the three tested groups.
Within the limitations of this study, it can be concluded that:
1. Rotary systems with the same kinematics resulted in similar apical debris extrusion.
2. Neither of used rotary systems resulted in an ideally clean canal.
3. Rotary systems with same kinematics and cross sections resulted in similar canal cleanliness.