الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 127 |  |  |
| | | from | 127 | | |
Abstract
Our study was conducted to evaluate the efficiency of 3 rotary Ni-Ti retreatment systems which are protaper, Fanta and M3 progold.
Amount of remaining filling material on canal walls, the time required for retreatment process, number of fractured files, amount of debris extrusion was evaluated.
The total number of sample was sixty canals in thirty mesial root of lower mandibular first molar type III and was randomly divided into three groups of twenty canals according to retreatment system used. In group (I) retreatment was done using protaper universal retreatment files. In group (II) retreatment was done using Fanta AF retreatment files. In group (III) retreatment was done using M3 Pro gold retreatment files.
Teeth were decoronated, instrumented using F1 protaper shaping file then obturated with gutta percha and adseal using cold lateral compaction technique. After obturation specimens were sealed with composite and stored in 100% humidity & 370c to allow sealer to set.
After retreatment teeth were splitted longitudinally and imaged using stereomicroscope then analyzed by IMAGE J software to measure percentage of remaining root filling material in coronal, middle and apical third of root canal.
The time required for retreatment was measured from the first retreatment file used until no obturation material can be distinguished on the last file.
Number of broken files were evaluated by its length shorter than normal with loss of canal patency.
Amount of debris extrusion was evaluated by subtracting the preretreatment and postretreatment weight of the Eppendorf tubes for each group.
Protaper retreatment file system left more remaining root filling material than Fanta and M3 progold system with significant difference. No significant difference between Fanta and M3 progold in the amount of remaining guttapercha.
Remnants of root filling material were left in apical and middle thirds more than coronal third with significant difference.
Protaper retreatment file system was faster than Fanta and M3 progold retreatment file system regarding time required for retreatment with significant difference.
Regarding number of fractured instruments 3 protaper D3 (20 7%) files, 2 Fanta RTR1 (20 7%), 5 M3 progold files 4 M3RT1(20 7%) and 1 M3RT2 (25 8%) were broken.
Fanta showed the highest amount of debris extrusion in comparison to protaper and M3 progold retreatment systems with significant difference.