The aim was to evaluate debris and smear layer at 1, 3 and 5 mm from the foramen of single-file systems WaveOne Gold â and Reciproc Blue â . Thirty single-rooted teeth were prepared using one of the following NiTi instruments WaveOne Gold â and Reciproc Blue â . Root canals were observed under a scanning electron microscope. The presence of debris and smear layer at the apical third of root canals was evaluated. Data were analysed by Friedman and Wilcoxon tests. WaveOne Gold â produced significantly less debris and smear layer compared to Reciproc Blue â . However, the mean amount of debris was significantly different within distances for WaveOne Gold â , while no difference were observed for Reciproc Blue. The mean amount of smear layer was not significantly different within distances with WaveOne Gold â and Reciproc Blue â . Both systems showed debris and smear layer in the apical third; nevertheless, WaveOne Gold â showed better results.

Aim:The aim of this systemic review is to investigate these parameters by analyzing the characteristics of fractured instruments to determine which is the most relevant mechanical stress that induces intracanal separation in vivo. Background: The fracture of nickel-titanium (Ni-Ti) instruments is a result of flexural fatigue and torsional fatigue. An electronic search was conducted in MEDLINE database, Web of Science, and Cochrane following preferred reporting items for systematic reviews and meta-analyses guidelines. Data were collected and the key features from the included studies were extracted. Overview quality assessment questionnaire scoring assessed the quality of the articles. A total of 12 articles were selected, where the lowest score was 13. Review results: Considering Ni-Ti rotary instruments, this overall evaluation comprehends 939 broken instruments with an incidence of fracture of 5%. Out of the 12 selected articles, 10 studies revealed that flexural failure was the predominant mode (range of 62-92%). It appears that motion plays an important role when it comes to mechanisms of fracture. The majority of defects found in hand-operated instruments were in the form of torsional failure. Although the major cause of separation of rotary instruments is flexural fatigue, smaller instruments show more torsional fracture than the larger instruments. The average fragment length was found to be 2.5 mm and 3.35 mm, respectively, for torsional failure and flexural failure. The risk of bias depends on fractographic analysis. Conclusion: Flexural fatigue is the predominant mode of fracture in rotary Ni-Ti instruments. The type of motion and size of the instrument seem to affect the mechanism of fracture. Fragment length may show a strong association with the type of fracture mechanism. Clinical significance: This systemic review found that flexural fatigue is the most relevant mechanical stress that induces intracanal separation in vivo. Moreover, in clinical practice, the fragment length might be an excellent indicator of the type of fracture.

Aim: This study aimed to assess the potential of the hybrid heat treatment (HHT) technique for shaping severely curved canals. Background: This innovative HHT technique combines the use of both Ni-Ti austenitic and martensitic Ni-Ti files, with a simplified sequence, to properly utilize the different files' properties. Case description:The operative technique started with canal scouting and determination of working length using a size 10 SS K-file. Then, a specific sequence was applied using the F1 20.06v Ni-Ti austenitic file (EdgeTaper) for the preparation of the coronal and middle parts of the canal. This step was followed by S2 20.04 and F1 20.06v martensitic Ni-Ti files (EdgeTaper Platinum) to enlarge the canal until the apex reached. No intracanal breakage of any instruments or deformation of flutes was recorded. Conclusion:The present study describes a new HHT technique aiming at simplifying procedures and taking most of the different characteristics of the different heat treatment; the clinical cases seem to show its potentialities in terms of safety, speediness, effectiveness, and preservation of original anatomy. Clinical significance: The cases show the advantages of the newly proposed technique over a traditional approach to properly shape complex anatomies with only a few Ni-Ti rotary instruments number.

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Background: An endodontic treatment consists in cleaning, shaping and filling the root canal system. Irrigation is the chemical part of the process that ensures the total removal of debris. Activating the irrigation solution will improve and accelerate the process. Objective: The aim of the study is to evaluate the removal of debris and smear layer at 1, 3, and 5mm from the foramen after needle irrigation, EndoActivator® and Irrisafe®. Sixty single-rooted teeth were prepared using Primary WaveOne Gold®. Methods: Teeth were randomly assigned to 4 groups (n=15): needle irrigation - Group A, EndoActivator® for 1 min - Group B, Irrisafe® for 1 min - Group C, Irrisafe® for 30 sec - Group D. Root canals were observed under a scanning electron microscope. Data were analyzed by Friedman and Wilcoxon tests. Results: Debris was significantly higher with group A compared to B, C, and D. Irrisafe® was significantly more effective in removing the smear layer than the other groups. However, activation techniques showed less debris and smear layer than needle alone nevertheless. Conclusion: Irrisafe® showed the best results regardless of time.