Purpose: The aim of this study is to evaluate the apical debris extrusion after root canal preparation using different pediatric rotary file systems in mandibular second primary molars.
Methods: Forty mandibular second primary molars were used in this study. Teeth were randomly di-vided into four experimental groups for the shaping of their distal roots. Group (G)1: Hand files, G2: Endoart Pedo Blue, G3: M3 Immature Blue, and G4: AF Baby rotary file were used for root canal prepara-tion. The Myers and Montgomery model was used to measure the amount of apical debris by evaluating the pre- and post-weight of the Eppendorf tube. Data were analyzed using one-way analysis of variance and Tukey post-hoc tests (p < 0.05).
Results: Among all file systems, the highest apical debris extrusion was observed in the G1 (hand file) group, and the least apical debris extrusion was observed in the G4 (AF Baby) group. However, there was no statistically significant difference between the G2 (Endoart Blue), G3 (M3 Immature Blue), and G4 (AF Baby) groups (p > 0.05).
Conclusion: All shaping techniques used in the study resulted in apical debris extrusion.

Purpose: The purpose of this study was to compare the efficacy of chitosan (CS)-derivative and its bind-ing to citric-acid with chelators traditionally used in clinical practice.
Methods: 50 lower pre-molars were decoronated, standardizing a length of 15 mm, subsequently were instrumented with telescopic technique up to diameter 40.02, irrigated with 5% sodium hypochlorite. The samples were divided according to the treatment of smear layer (SL) (n = 10). Group I: 5% CS-oligo-saccharide, Group II: 5% CS-oligosaccharide citrate, Group III: 10% citric acid, Group IV: 17% ethylenedi-aminetetraacetic-acid (EDTA), and Group V: distilled water. The samples were sectioned longitudinally, sputtered with gold, and observed with scanning electron microscope (SEM) under ×2000 and ×5000 magnifications. Data were analyzed using Kruskall-Wallis test followed by Mann-Whitney U test.
Results: In the apical third, CS-oligosaccharide citrate demonstrated better SL removal compared to the other groups (p < 0.05) but not with EDTA (p > 0.05). In the cervical and middle thirds, no differences were found (p > 0.05).
Conclusion: CS-oligosaccharide and CS-oligosaccharide citrate demonstrated similar chelating effect to citric acid and EDTA but were not superior.

Purpose: The present in vitro study aimed to compare the tissue dissolution ability of a 5% sodium hypochlorite solution at 3 different temperatures.
Methods: Thirty standardized fragments were prepared from bovine muscle tissue and randomly divided into 3 experimental groups (n = 10) according to the temperature of the sodium hypochlorite. The tissue was immersed in a 1.5-mL test tube containing 20 mL of sodium hypochlorite at the specific temperature and stored for 15 min. The solution was agitated with an ultrasonic tip working for 1 min. Then the solution was filtered, and the tissue sample was dried. The weight loss of the tissue was measured as dissolved tissue by the sodium hypochlorite. A one-way analysis of variance was used to compare the mean dissolved tissue weight between groups (p < 0.05).
Results: The highest dissolution values were found in the 60°C sodium hypochlorite group, achieving significantly greater mass loss (p < 0.05), while no significant difference was found between the solutions applied at 20°C and 2.5°C (p > 0.05).
Conclusion: This in vitro study found that the application of sodium hypochlorite by cooling for cryo-therapy did not alter its capacity for dissolving organic tissue compared to application at room temperature.

Purpose: To evaluate the effect of storage time on the dislocation resistance of core material to root canal sealer in standardized artificial root canals.
Methods: A single root canal with a round shape was selected using cone-beam computed tomography imaging, and root canal treatment was performed. The root was scanned with microcomputed tomography, and the data were exported as a stereolithography file. Forty artificial roots were manufactured using 3D printing technology. The artificial root canals were obturated using a single cone technique. The roots were divided into two groups according to the storage time of filled roots: 7 days and 30 days (n = 20), and stored at 37°C and 100% humidity. After each storage period, 2-mm sections were taken from the middle part of the roots. The sections were tested on a universal testing machine. The dislocation resistances (MPa) were calculated, and the data were analyzed using the Shapiro–Wilk test and independent samples t-test (α =.05).
Results: The dislocation resistance of the filling material was significantly higher in the 30-day storage time group compared to the 7-day group (p <.05).
Conclusion: The storage time of the root fillings affected the dislocation resistance in the standardized experimental setup with artificial roots.

Purpose: Due to its vulnerable structure in the danger zone, the selection of an endodontic instrument becomes very important to avoid excessive root canal preparation in this area. It was aimed to compare the effect of different retreatment file systems and solvents on the amount of removed dentin thickness in the danger zone of mandibular molar teeth using cone beam computed tomography (CBCT).
Methods: A total of 120 mesiobuccal root canals were prepared and obturated with BioRoot RCS root canal sealer using the single cone technique. Specimens were divided randomly into three groups according to the retreatment system used (n = 40): ProTaper Universal Retreatment (PTUR), Reciproc Blue (RB), and XP-Endo Retreatment (XPR). Thereafter, each group was divided into two subgroups according to whether a solvent was used or not (n = 20). CBCT images were obtained from specimens before and after removing root canal filling materials. The removed dentin thickness was calculated in axial sections obtained from 4 mm below the furcation area. Data were statistically analyzed using two-way ANOVA and Bonferroni tests (p = 0.05).
Results: In terms of removed dentin thickness, no significant difference was found between retreatment systems when used with solvent (p = 0.964), whereas a significant difference was found when they were used without solvent (p = 0.004). The removed dentin thickness in RB was lower than in XPR (p = 0.008) and PTUR (p = 0.018).
Conclusion: Solvent did not affect the amount of removed dentin thickness of XPR and PTUR files. Removed dentin thickness of RB was less when used without solvent than with solvent.

Purpose: New solutions are needed to overcome the disadvantages of irrigation solutions that are frequently used to remove the inorganic part of the smear layer. The goal of the current study was to compare the effect of 5%, 10%, and 17% GA, 9% HEBP, 17% EDTA, and 10% CA on the fracture strength of endodontically treated premolars.
Methods: Eighty-eight mandibular premolar teeth were selected. Eleven intact specimens were preserved as negative controls. After root canal preparation, the specimens were divided into 8 groups for the final irrigation procedure: Positive control (distilled water), 17% EDTA, 10% CA, 9% HEBP, 5% GA, 10% GA, and 17% GA (n = 11). After the final irrigation procedure, the root canals were obturated. Access cavities were filled with composite resin. A universal testing machine was used to measure the force required to fracture the specimens. Data were statistically analyzed.
Results: The negative control group showed higher fracture strength than all other groups except the positive control group (p < 0.05). There was no statistically significant difference among the EDTA, CA, HEBP, and GA groups (p > 0.05).
Conclusion: Within the limitations of this study, 1-minute use of 17% EDTA, 10% CA, 9% HEBP, 5% GA, 10% GA, and 17% GA as final irrigation solutions, in combination with NaOCl, had no effect on the fracture resistance of premolar teeth.

Purpose: To compare and assess the efficacy of cryotherapy in reducing postoperative pain after bio-mechanical preparation in irreversible pulpitis and/or apical periodontitis in single-rooted teeth.
Methods: A total of eighty patients presenting with single-rooted teeth exhibiting irreversible pulpitis and/or apical periodontitis were subjected to a randomized allocation into two groups of 40 each. Irrigation was done using 5% sodium hypochlorite along with a heated plugger to warm it at 90°C for 5 seconds in all 80 teeth. Group 1 underwent final irrigation utilizing normal saline at room temperature. Group 2 received final irrigation using normal saline refrigerated between 2-5°C. Pain levels were assessed and recorded before the procedure and at 24 and 48-hour time intervals.
Results: No statistically significant differences were found in VAS pain scores between Group 1 and Group 2 at the 24-hour mark. Conversely, at the 48-hour mark, a significant statistical difference was observed in the VAS pain scores between Group 1 and Group 2. Group 1 exhibited a higher mean VAS score compared to Group 2.
Conclusion: Based on the constraints inherent in this study, it can be inferred that employing cryo-therapy with the use of cold saline at 2°C to 5°C as a final irrigant leads to a reduction in postoperative pain at 48 hours.

Purpose: The aim of this study was to survey the outcomes of endodontic microsurgeries performed by endodontic postgraduate residents.
Methods: Clinical and radiographic data of 70 patients who underwent endodontic microsurgery between January 2015 and March 2022 were collected through the clinical electronic system of the university clinics. Each patient was contacted for a follow-up appointment. Clinical and radiographic examinations were performed for each patient, and the success rate and tooth survival were analyzed.
Results: Sixteen patients (24 teeth), mostly female, attended the follow-up appointments with an average follow-up period of 18 months. Most of those who did not show up had no problem and some did not respond, while the rest changed their addresses and others were not interested in attending. Persistent periapical infection followed by overfilling was the most common reason for periapical surgery. All teeth (100%) survived. Out of 18 maxillary teeth, complete healing was observed in 44.4% and incomplete healing in 44.4%, whereas only 33.3% of six mandibular teeth displayed complete healing and 66.7% had incomplete healing. The combined success of complete and incomplete healing was 91.66%. However, the distribution of the outcome levels within each location, maxillary and mandibular, showed no significant difference (p > 0.05).
Conclusion: A predictable high success rate of endodontic microsurgery treatment performed by endodontic postgraduate residents of complete and incomplete healing was achieved.

Purpose: The study’s objective was to evaluate the efficiency of various irrigation activation methods for removing gutta-percha and sealer using Micro-CT and SEM after retreatment with rotary files.
Methods: Twenty-one permanent single-rooted teeth that were extracted and had a single canal were decoronated to a length of 16 mm. AH Plus sealer was used for obturating the root canals. Following obturation, Micro-CT scanning was carried out (S1). Another Micro-CT scan was performed following the elimination of the original filling material using ProTaper Universal retreatment files (S2). Next, each of the 21 samples was divided into three groups (n = 7): Group 1: XP-Endo Finisher (XPF); Group 2: Passive Ultrasonic Irrigation (PUI); Group 3: SWEEPS. Subsequent irrigation activation technique by one of each system was followed by the final Micro-CT scanning (S3). After calculating the remnant volume of the filling material, a single specimen was examined under a scanning electron microscope for every group. Statistical evaluation was accomplished utilizing the Kruskal-Wallis and Shapiro-Wilk tests.
Results: After analyzing the samples, S1 and S2 scanning results revealed no statistically significant differences among the three groups (p > 0.05). Furthermore, no significant difference in the final volume of residual filling material (S3) between the three groups was found statistically.
Conclusion: In summary, XPF, PUI, and SWEEPS techniques are equally efficient at removing remnant filling materials after conventional retreatments.

In this case series, radiographic images of healing lesions resulting from non-surgical root canal treatments and follow-up of periapical lesions caused by traumatic occlusion, untreated trauma injuries, inadequate root canal treatment, and pulp necrosis with deep caries and internal resorption are presented. The treatment of four cases consisting of mandibular and maxillary incisors, molars, and premolars with a lesion was completed by filling the root canals after opening the access cavity, applying bio-mechanical preparation, and canal medication with calcium hydroxide. The symptoms of the patients were evaluated with control examinations; lesion healing was followed by periapical radiographs taken from the patients. As a result of clinical and radiographic evaluations, it was observed that the lesions were greatly reduced, and bone formation occurred. Periapical lesions can be healed by performing conservative root canal treatment in line with correct procedures, even without surgical procedures.