Supervisor : Abeer Hashem Mahran, Ahmed Hussien Abuelezz. Includes Arabic Summary.Mohamed, Huda Ashri Atef El-Sayed Mohamed,2024-05-272024-05-272024.EG-CaMIUDNT Ths687 M.Sc. 2024https://iorep.miuegypt.edu.eg/handle/20.500.13071/245DISSERTATION NOTE-Degree type M.Sc.DISSERTATION NOTE-Name of granting institution Misr International University, Faculty of Oral and Dental MedicineIncludes bibliographic references.The purpose of the study is to evaluate two different obturation techniques, single cone and cold lateral compaction used with bioceramic sealer (Neosealer Flow, Avlon Biomed, Inc). The evaluation is regarding the impact of obturating technique on depth of penetration of bioceramic sealer inside dentinal tubules at three different thirds of root canal. Also, the evaluation is regarding the impact of obturating technique on the amount of remaining obturating material inside root canal and its depth inside dentinal tubules at three different thirds of root canal system after retreatment using machine driven files with continuous rotation motion. A total of 24 single rooted permanent premolars were collected to conduct this study. Decoronation was done followed by scouting and irrigation. All samples were prepared using Hyflex EDM files in continues rotation motion then samples were obturated with bioceramic sealer and one of two different techniques single cone and cold lateral compaction techniques. After incubation, 12 samples was retreated with Protaper Universal Retreatment files followed by X2 and X3 Protaper Next files. Three samples were sectioned vertically to be examined under CLSM to assess penetration depth of bioceramic sealer inside dentinal tubules before and after retreatment phase. Samples of subgroups with retreatment phase were sectioned vertically to be examined under stereomicroscope to assess filling material remnants inside canal system after retreatment. After testing samples, raw data were collected for the statistician to get the final results for each test. Regarding penetration depth, results showed that there were statistically no significant differences between the two obturating techniques while there were statistically significant differences in intragroup comparison between three sections coronal , middle and apical. Highest values were in coronal sections followed by middle and apical . According to stereomicroscope results, there was statistically significant differences between single cone technique and lateral compaction technique. The highest values were found with lateral compaction technique.145 pages : illustrations, photo ; 29 cmEndodontics