Objective: The aim of our study was to compare the effect of use of different glide path systems before root canal preperation with WaveOne System on dentinal crack development.
Methods: For this study one hundred fifty molars with mesial roots curvatures of 20°–40° were selected. All the other teeth were divided randomly into 9 groups with 15 teeth in each. These groups were: K-type file, PathFile, G-files, Proglider, Pathfile/ WaveOne, G-File/WaveOne, Proglider/WaveOne, K-file/WaveOne and WaveOne. After preparation teeth were sectioned horizontally at 1, 2, 3, 4, 5, 6, and 9 mm levels and the samples were examined for identifying dentinal crack formation with a stereomicroscope at a ×15 magnification. Dentinal crack formation in samples were statistically analyzed using chi-square test.
Results: The control, hand file, and PathFile groups did not show any dentinal cracks. WaveOne and G file/WaveOne groups led to highest rate of crack formation (p<.05). There was a significant difference between the control/hand file/Pathfile groups and the all other groups (p<.05).
Conclusion: WaveOne and G file/WaveOne groups led to highest rate of crack formation.

Objective: To compare the cyclic fatigue resistance of HyFlex CM, Typhoon CM, and EdgeFile X3 NiTi files with a Controlled Memory alloy under a static model.
Methods: Twenty HyFlex CM 25.06, 20 Typhoon CM 25.06, and 20 EdgeFile X3 (25.06) instruments were included in this study. The cyclic fatigue tests were performed using a static cyclic fatigue testing device, which have an artificial stainless steel canal with 60° angle of curvature and a 5 mm radius of curvature. The files were randomly divided into three groups (Group 1: HyFlex; Group 2: Typhoon; Group 3: EdgeFile X3). All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to failure (NCF) was calculated. The data were analyzed statistically using Kruskal–Wallis test (p<.05).
Results: The EFX3 C2 (4523.15±582.70) file system had the highest NCF, followed by the HF CM (4439.15±517.27) and TYP CM (4395.15±387.36) files. However, there was no statistically significant between-group difference in the NCF (p>.05).
Conclusion: Within the limitations of the present study, there was no statistically significant difference between the cyclic fatigue resistance of the HF CM, TYP CM, and EFX3 NiTi files.

Objective: To compare the effectiveness of IrriSafe, EndoActivator, CanalBrush, and conventional irrigation in the removal of the smear layer after retreatment procedures.
Methods: One hundred human maxillary central incisors with single and straight root canals were instrumented up to #40.02 with manual K-files and obturated using the continuous wave of condensation technique. Removal of the gutta-percha and sealer was performed using ProTaper Universal retreatment system. Then, the final activation techniques was performed using one of the following techniques: IrriSafe, EndoActivator, CanalBrush, or conventional irrigation. Teeth were split longitudinally, and specimens were observed under a scanning electron microscope. Data were analyzed with Kruskal-Wallis test.
Results: There was no statistically significant difference between the EA, CB, and CI groups in the total scores of the smear layers seen in the root canals (p>.05), but the IS group had statistically significantly more smear layer removed than the CI group (p<.05).
Conclusion: Within the limitations of this in vitro study, none of the final activation techniques applied after the retreatment procedures could totally remove the smear layer in the root canal walls.

Objective: To evaluate the effect of adaptive motion on shaping ability of Twisted Files nickel-titanium files in simulated S-shaped canals.
Methods: Forty S-shaped canals in resin blocks were prepared to an apical size of 0.25 mm using Twisted Files with rotary or adaptive motion (n=20 canals/group). Composite images were made from the superimposition of pre- and post-instrumentation images. The amount of resin removed by each system was measured by using a digital template and image analysis software. Canal aberrations were also recorded. The data were statistically analyzed by using Mann-Whitney U test.
Results: There was no significantly difference between adaptive and rotary motion groups (P > 0.05). No instrument fracture or canal aberrations were inspected during canal preparation.
Conclusion: Within the limitation of the present study, adaptive and rotary motions were safe to use and were able to prepare the canals efficiently.

In Endodontic, one of the most crucial problem that can result in the loss of teeth is periapical lesion. In the development of periapical lesion in periapical tissues, not only the presence of infected pulp but also the toxins, metabolic products, chemical agents, mechanical irritations, foreign substances, trauma and host defense of existing microorganisms also play a role. Radiographic findings, clinical oral examination and differential diagnosis are used in the diagnosis of periapical lesion. Even though endodontic treatment option combined with apical surgery could be an option for treatments of large periapical lesions, conventional root canal treatment should be the first choice that combined with long-term follow-up after treatment. The aim of this case report is to present a complete clinical and radiological healing of teeth relation with a large cyst-like periradicular lesion treated only with root canal treatment and without the need for a surgical treatment.