الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 111 |  |  |
| | | from | 111 | | |
Abstract
This ex vivo study was carried out to evaluate the efficacy, cleaning ability and safety of two rotary NiTi systems versus H-file alone and in combination with GG, with and without the use of Chl during root canal retreatment. One hundred and twenty recently extracted human single canalled teeth were used in the study. The teeth were divided into four main groups (30 teeth each); group A (retreatment with PTR), group B (retreatment with R-Endo), group C (retreatment with H-file) and group D (retreatment with H-file in combination with GG). Each group was subdivided into two subgroups (1 and 2) (15 teeth each). Subgroups (A1, B1, C1 and D1) Chl solvent was used. While, in subgroups (A2, B2, C2, and D2) no solvent was used during Gp removal. The time required for complete removal of Gp was recorded for all specimens using a stopwatch. Teeth were splitted longitudinally and photographed. These photos were transferred to the computer. Then Cleanliness of the root canal walls was calculated by measuring the ratio of the surface area of the remaining filling material to the total canal surface area. This ratio was expressed as a percentage. (Adobe Photoshop Cs3 Extended version 10.0 2007 United States). Three representative specimens of different groups were selected for internal root surface analysis under the SEM to enhance inspection of the canal walls and the remaining filling material. Also, any procedural errors during the retreatment procedure were recorded for all specimens. The results showed that the fastest technique to remove Gp/sealer was the Protaper Retreatment system used with Chl (PTR/Chl, subgroup A1) while the slowest technique was the Hedstrom file used without Chl (subgroup C2). The rotary NiTi systems (R-Endo and Protaper retreatment systems) showed significantly shorter retreatment procedure time than the conventional instrumentation (H-file and H-file combined with GG). In all groups, the retreatment time in the Chl subgroups is significantly shorter (p<0.05) than in the non Chl subgroups.