Objective A retreatment is a conservative approach than periapical surgery in case of failed root canal treatment. Retreatment techniques that are efficient and faster should be the main concern to treat endodontic failure. This study aimed to compare the time required by various hand and rotary retreatment systems for the retrieval of gutta-percha (GP) from root canals. Materials and Methods A total of 120 extracted single-rooted premolar teeth with straight canals were chosen. Biomechanical preparation was completed using the Step-Back approach keeping the master apical file size 35. Then, teeth were down-packed and back-filled with System B device, along with AH Plus sealer. The teeth were categorized into six groups (n = 20) at random as per techniques applied for retrieval of GP: group I hand instrumentation (Hedstrom files and Gates-Glidden drills); group II ProTaper Universal Retreatment (PTUR) system; group III Mtwo Retreatment (Mtwo R) system; group IV D-RaCe; group V R-Endo; and group VI Mani Gutta Percha Remover (NRT-GPR). A chronometer was used to measure the time required for retrieval of GP. Data were examined by comparative evaluation of one-way analysis of variance and chi-square test. Results Among all the retreatment techniques used, D-RaCe was faster in GP retrieval than other groups. NRT-GPR system also took less time than other groups except for the D-RaCe system. The Mtwo R system was the slowest among all groups. Conclusion D-RaCe retreatment instruments required extensively less time for retrieval of GP than other groups (p < 0.001).

Aim: The study aims to evaluate the antimicrobial properties and push-out bond and compressive strength of mineral trioxide aggregate (MTA) mixed with different ratios of triple antibiotic paste (TAP) against Enterococcus faecalis. Methodology: Antimicrobial effect was evaluated using agar well diffusion method. Materials were divided into three groups. Group 1: MTA, Group 2: MTA + TAP (2:1 ratio), and Group 3: MTA + TAP (1:1 ratio) zone of inhibition were determined after 24 h of incubation at 37°C. To evaluate push-out bond strength, 30 extracted teeth were decoronated to a length of 13 mm, followed by root canal treatment, the root resected at 3 mm from the apex, and root-end cavity was prepared and filled. Cylindrical specimens (n = 10 per group) of size 3 mm × 6 mm were prepared of MTA, MTA plus triple antibiotic 2:1 and 1:1 ratio and tested for compressive strength using Instron Universal testing machine. All the data were statistically analysed using Krusal–Wallis test (P < 0.05). Results: MTA + TAP (1:1 ratio) exhibited highest antimicrobial activity than MTA + TAP (2:1 ratio) and MTA alone. The push-out bond and compressive strength of Group 1 (MTA alone) was better compared to two groups containing MTA in combination with TAP; however, no statistical significant difference was found between the three groups. Conclusion: Combination of TAP with MTA increases the antimicrobial activity against E. faecalis without compromising much of the compressive and push-out bond strength, hence can be advocated for root-end filling.

Aim: Using N acetyl cysteine (NAC) and Chlorhexidine as final irrigants, the study aims to examine the push out bond strength of distinct sealers. Materials and Methods: Access and biomechanical preparation were done on decoronated 80 single-rooted teeth. Canals were alternatively irrigated using 5ml of 5.25% NaOCl and 5ml of 17% EDTA solution during instrumentation. On the basis of final irrigation procedure, the samples are divided into two groups: Group 1 – NAC and Group 2 – 2% Chlorhexidine. Using paper points, canals were dried and subdivided depending on the sealers used, Group 1A and 2A- AH plus and 1B and 2B- BioRoot RCS. Teeth were obturated and middle root sections were tested for push-out bond strength using universal testing equipment. Statistical analysis was done. Results: NAC with AH-plus sealer had the maximum push-out strength, whereas Chlorhexidine with BioRoot RCS sealer had the lowest. Conclusion: NAC increases the bond strength of the obturating materials as the final irrigant. NAC can be considered as a final irrigant for endodontic therapy.

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