Post space preparation
After the random division of specimens, the access cavities were reopened again with round bur mounted on a high-speed handpiece until completely removed. Post space preparation protocol was followed including removal of gutta percha from the two coronal thirds of the roots; which was approximately 10 mm long, leaving ±4 mm of gutta percha apically as an apical seal, indicating a long post space using peeso reamer drills (MANI, INC., Tochigi-Ken, Japan) that were mounted on a low-speed handpiece, length adjusted by endodontic ruler and then used in the order of #1, #2, #3 and #4 sequentially, to achieve a standardized post space preparation; 0.7, 0.9, 1.1 and 1.3 mm in diameter respectively. 10 mm of gutta percha was removed from all canals leaving 4 mm of coronal seal, to standardize the length of preparation in all specimens [