الفهرس 
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Abstract
Root perforation is one of the most common causes of endodontic treatment failure as it prevents the hermetic seal of the root canal system as it allows a pathway for microorganisms either from periodontal tissues or perforation.
The ideal perforation repair material should be biocompatible, dimensionally stable, antibacterial, easy to manipulate, radiopaque, and unaffected by blood contamination, tissue fluid, and different root canal irrigation solutions (4) if we need to complete the endodontic treatment in a single visit.
Our study aimed to assess the effect of 5% NaOCl and 17% EDTA solutions on the push-out bond strength, sealing ability, and chemical structure of three of the root repair materials (MTA Angelus, Biodentine, and a recently marketed Well-Root bioceramic putty)
For the push-out bond strength test, we used dentine discs (n=90) from the mid-root of human-extracted single-rooted teeth. After enlarging their lumen into 1.5 mm using the Gates Glidden burs they were randomly divided into 3 main groups (n=30) according to the repair material used: MTA, Biodentine, and Well-Root putty. The repair materials were condensed and allowed to be set for only 10 minutes. After that each main group was subdivided into 3 subgroups (n=10) according to the irrigation solution used: 5 % NaOCl, 17% EDTA, and a control group with no irrigant used but moist cotton pellets placed on the specimens. After immersion of the two experimental groups in their corresponding solutions for 30 minutes they were rinsed, and all specimens were incubated for 72 hours for a complete setting.
After complete setting, the push-out bond strength was evaluated using the universal testing machine and the mode of failure was examined using the stereomicroscope. After the analysis of the results, we found that NaOCl increased the bond strength of the Biodentine and bioceramic putty but decreased that of MTA while EDTA decreased the bond strength of the three repair materials. Most of the samples exhibited adhesive failure type.
For the sealing ability test, seventy-two lower first and second extracted molar teeth were selected to be used in that part of the study. A standard artificial perforation made in the floor of each molar was made then the teeth were randomly divided into 3 main groups (n=24) according to the repair material. After repairing the perforations with the corresponding material, each main group was subdivided into 3 subgroups (n=8) according to the irrigation solution: 5% NaOCl, 17% EDTA and the third group was a control group in which a moist cotton pellet was placed over the perforation repair material without exposure to any irrigant.
The repair materials were allowed to be set for 10 minutes. Then the two experimental groups were immersed in either NaOCl or EDTA for 30 minutes after that time they were rinsed and all the teeth were incubated for 24 hours for a complete setting after that the repaired perforations were exposed to Methylene blue dye for 72 hours then the dye penetration was examined using the stereomicroscope. After the analysis of the results, we found that NaOCl insignificantly increase the sealing ability of Biodentine and putty but significantly decreased the sealing ability of MTA while EDTA decreased the sealing ability of the repair materials especially the putty group.
For the XRD method, nine resin cylindrical molds (8 mm in diameter and 4 mm in height) were prepared and divided into 3 main groups (n=3) according to the root repair materials. After mixing the three root repair materials, they were packed into the molds and allowed to set for one hour then each main group was subdivided into 3 subgroups (n=3) according to the irrigant used: 5% NaOCl, 17% EDTA, and a control group in which no irrigation was used. After that the discs that were exposed to the irrigants were rinsed then the nine groups were incubated for 3 days for a complete setting.
After the complete setting of materials, they were converted into fine particle powder to be examined by the XRD method and we found that NaOCl increased the release of Ca(OH)2 from the three materials and vice versa in the EDTA groups.