الفهرس 
Introduction .Only 14 pages are availabe for public view
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Abstract
The present study aims to compare TF Adaptive, Reciproc file, and PTN regarding bacterial reduction, apically extruded dentin, and canal cleanliness in vitro and to compare postoperative pain in vivo after cleaning and shaping with each.
The files used in the present study were the ML kit of the TF adaptive, Reciproc R50, and all the ProTaper Next Kit.
Sixty-eight freshly extracted lower premolar teeth with single straight roots were selected for the study. The teeth were accessed using carbide round bur, then complete de-roofing of the pulp chamber. The working length (WL) utilized was 1 mm short of the length of the initial instrument (size 10). only the samples with a working length between 22 and 23 mm were selected for the study.
The canals were enlarged for the bacterial reduction group until file #20. Teeth were sterilized in an autoclave for 20 minutes at 121°c, then placed in a nutrient broth. Each root canal was filled with E. faecails suspension using sterile 1-ml insulin syringes then all teeth were incubated at 37°c in sealed vials for seven days. Samples were classified into four main groups according to the motion type; each contains eight samples. The control group had only irrigation using bidistilled water without cleaning and shaping. After mechanical instrumentation, sterile paper points (#50) were placed at the WL and used to soak up the canal contents, then transferred to test tubes containing saline. The colony-forming units (CFUs) grown are counted.
For assessing the apically extruded dentin, 30 samples were chosen, and the teeth were mounted first to preweighted tubes for collecting the apically extruded dentin before being prepared. All tubes were incubated at 37°C for 15 days before being weighed again to evaporate the irrigant in the tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight.
The prepared samples were sectioned longitudinally into two with linear precision saw to assess the cleaning efficiency. Then Scanning electron microscope was used to take photos of the sectioned roots at magnifications 500X and 2500X. These photos were analyzed to determine the amount of dentin debris in each segment using the Hülsmann scoring system.
Regarding the postoperative pain study, a randomized clinical trial (RCT) was carried out in the Department of Endodontics, Faculty of Dentistry, Ain Shams, and Fayoum University on 36 cases divided into three equal groups. First, the pre-operative pain was recorded, the selected teeth were accessed and then mechanically prepared, after which the patient’s pain score was recorded at 6 hours, 12 hours, 72 hours, and 1 week. Assessment of pre and post-operative pain was done by using the Numerical Pain Scale.
The results of the bacterial reduction test showed significant differences between different groups, for the weight of debris extrusion study results showed no significant difference between groups.
The results of the cleaning efficiency study in the coronal third showed a significant difference between different groups. In contrast, there was no significant difference in the middle and apical one-third. There was no significant difference between the twisted file and reciproc between different root sections; in the ProTaper NEXT, there was a significant difference.
There was no significant difference between the three files for the postoperative pain study regarding the different time intervals. At the same time, in the intragroup comparison, the 12 h showed significant differences in the three files.