**12. Fracture resistance**

*Oral Diseases*

in the root canals at 2 months.

endodontic re-interventions.

**11. Endodontic reintervention**

completely removed from the root canal system.

Shokouhinejad et al. [45] evaluated the bond strength of EndoSequence BC endodontic cement (Brasseler USA, Savannah, GA) when used with gutta-percha in the presence or absence of moisture within root canals. The mean bond strength of EndoSequence BC sealant and filler in the wet channels was significantly higher than that of the dry 1 week. In contrast, there was no significant difference between dry and wet root canals at 2 months. In the dry channels, the adhesion strength increased significantly over time, while in the wet, the difference was not significant. The presence of moisture inside the root canals increased the bond strength of EndoSequence BC cement in 1 week. However, no difference was found between the bond strength of EndoSequence BC cement in the presence or absence of moisture

According to Oltra et al. [16], recently new bioceramic sealant cements have been marketed and are being used in endodontic practice. However, these bioceramic cements have limited research related to their removal ability during

Uzunoglu et al. [46] evaluated the removal capacity of three different endodontic cements iRoot SP (bioceramic cement), MTA Fillapex (sealant based on MTA), and AH-26 (epoxy resin) from the root canal system. Channel filler was removed with ProTaper Universal Retreatment PTR. The time to reach the working length has been recorded. The roots were sectioned longitudinally and each half was evaluated using a stereomicroscope. Three observers scored every third of all specimens. In the GP/MTA Fillapex single cone group, the time required to reach working length was significantly shorter. The remaining filler material in the apical and middle thirds of the groups was similar. None of the tested cements can be

Oltra et al. [16] analyzed the ability to remove two BC sealer endodontic sealants compared to AH Plus using microcomputer tomographic analysis. Computed tomography was performed before and after obturation and retreatment and then analyzed for residual material volume. The specimens were sectioned longitudinally and the digitized images obtained with the microscope. In the present experiment, significant differences were found, since less root canal filling material was associated with the AH Plus group when using chloroform as a solvent when compared with the others. BC Sealer samples represented using chloroform as the solvent had better results than those removed without chloroform. The results of the present experiment demonstrate that the BC Sealer group presented significantly more residual obturator material than the AH Plus group, regardless of whether the two

Zuolo et al. [17] evaluated the effectiveness of the TRUShape system (Dentsply

Tulsa Dental Specialties, Tulsa, OK) compared to Reciproc (VDW, Munich, Germany) in unblocking channels filled with two different sealants and the working time required to achieve working length. A tomographic microcomputer was used to evaluate the removal of obturation material. The average volume of remaining obturator material was similar when comparing the two file systems. However, in the groups filled with bioceramic, the percentage of remaining obturator material was higher than in the groups filled with Pulp Canal Sealer. The clearance was faster in the groups that were filled with Pulp Canal Sealer when compared with bioceramics. There was no difference in the percentage of remaining shutter material when comparing file systems. However, Reciproc was faster

cements were associated with the use of solvent for their removal.

**186**

than TRUShape.

It is commonly believed that endodontically treated teeth are more fragile and more prone to fracture than vital teeth [47]. There are several factors that affect the strength of endodontically treated teeth: excessive tooth loss due to caries or trauma, dentin dehydration, access cavity preparation, instrumentation, excessive pressure during root filling, and preparation of intraradicular pins [48]. Reinforcement of the remaining tooth structure after endodontic procedures is one of the main objectives of rehabilitation. It has been suggested that the bioceramic cements may adhere to the dentinal surface of the root canal, strengthening the remaining dental structure, contributing to the long-term success of an endodontically treated tooth [49].

Topçuoğlu et al. [15] analyzed the strength of the values necessary to induce root fracture of teeth filled with three different endodontic sealants. Each specimen was then subjected to fracture testing using a universal testing machine at a speed of 1.0 mm/min (−1) until the root was fractured. The force required to fracture each specimen was recorded, and the data were statistically analyzed. The fracture values of the groups filled with bioceramic and gutta percha, and sealant based on epoxy resin and gutta percha, were significantly higher than those of group MTA and gutta percha. No significant differences were found between the bioceramic and epoxy resin groups, the Endosequence BC and AH Plus cements increased the strength of the values required to induce a root fracture of uniradicular premolars.
