Objective: The aim was to evaluate the resistance to vertical root fracture (VRF) of retreated roots using rotary and hand instrumentation.
Methods: Forty five extracted maxillary incisor teeth had their crowns removed to standardize the root lengths to 16 mm. Specimen root canals were prepared using ProTaperUniversal (PTU) rotary instruments and obturated using the cold lateral condensation technique with gutta-percha and AHPlus sealer. Teeth were randomly allocated into three groups (n=15). The first group was not retreated and served as a control group. The other two groups were retreated using either PTU retreatment instruments or hand-files, followed by obturation. The periodontal ligament of the filled roots was simulated. Specimens were embedded into self-curing acrylic and subjected to a vertically applied loading force (1.0 mm/min) in a universal testing machine until the root fractured. The data were recorded in Newtons and statistically analyzed (Kruskal-Wallis and Dunn multiple comparison tests, p<0.05).
Results: Retreated groups revealed decreased fracture resistance when compared with the control group (p<0.05). However, the difference in the median values among the rotary and hand instrumentation groups was not significant.
Conclusion: Within the limitations of this study, VRF risk increases in retreated teeth regardless of the instrumentation technique used.

Objective: In this study, three NiTi systems were compared in terms of the changes in canal curvature in both mesiodistal (MD) and buccolingual (BL) directions by cone-beam computed tomographic (CBCT) imaging. Methods: Mesiobuccal canals of 48 extracted human mandibular molar teeth with severely curved roots (32°-52°) were used. The teeth were randomly divided into three groups as follows; group1: WaveOne primary, group 2: OneShape, and group 3: ProTaper Next. The canals were instrumented to a master apical file size of #25 in each group. Preinstrumentation root canal curvatures were obtained by using CBCT images. The root canal curvature of each tooth was recorded. After the instrumentation, postinstrumentation CBCT images were obtained with the same method. Pre-and-postinstrumentation CBCT images were analyzed by using ImageJ software. Differences among the groups were analyzed by one way analysis of variance (ANOVA) or the Kruskal–Wallis test. Results: No difference was found among three instrumentation systems (p>0.05). Conclusion: Although all instruments demonstrated changes in root canal curvatures and straightened the root canals, these changes and straightenings may be inconsiderable in clinical conditions.

Aim: The aim of this study was to compare canal transportation in mesiobuccal root canals of extracted human mandibular molars instrumented with Twisted File Adaptive instruments with different kinematics.
Methods: A total of 60 extracted human permanent mandibular first molars with curved mesial root canals (25Results: There was no significant difference in canal transportation among the groups at the three studied levels (1, 4, and 7 mm from the root apex) (P > 0.05). The data for the centering ratio showed that there was no significant difference among the tested groups after instrumentation in each section of the root canal (P > 0.05).
Conclusions: The TF Adaptive instruments produce similar canal transportation and centering ratio when used with different movement kinematics.

Objectives: The aim of present study was to obtain information from senior dental students enrolled in Yeditepe University Faculty of Dentistry related to their confidence levels during endodontic treatment procedures.
Materials and Methods: Anonymous survey forms were distributed to 40 senior dental students enrolled in Yeditepe University Faculty of Dentistry. They were asked to indicate their self confidence level by Lickert’s scoring system ranging between 1 and 5.
Results: Retreatment procedure was a treatment type in which 15% of the students reported as having very little confidence. The majority of the students (67.5%) felt confident about taking radiographs during endodontic treatment. Meanwhile, irrigation was a procedure in which students felt high level of confidence (82.5%). Retrieval of broken instruments was determined as a procedure that was not experienced by 65% of the students.
Conclusion: Further research comprising other schools is warranted to identify the weak areas during endodontic treatment in order to bring resolutions for the delivery of skills during endodontic procedures.

AIM: To compare the time dependent effect of Vibringe, EndoVac, non-activated SAF, passive ultrasonic irrigation (PUI), and a conventional syringe on the reduction of E. faecalis in experimentally infected root canals.
METHODS: Sixty human mandibular premolar teeth with straight roots and single root canals, were infected with E. faecalis. One group saved as a control group and in the control group, neither irrigation nor instrumentation procedures were performed. The root canals were irrigated with Vibringe, EndoVac, non-activated SAF, passive ultrasonic irrigation (PUI) and conventional syringe using distilled water. After the irrigation procedures, samples were taken from root canals with paper points and incubated in blood agar plates. The colonies grown on the blood agar were counted and interpreted as colony forming units per millilitre.
RESULTS: Intergroup analysis revealed significant differences between the control and experimental groups (P < 0.001). The root canal irrigation with the conventional needle for four minutes was more effective than two minutes at reducing the number of cfu counts.
CONCLUSIONS: It can be concluded that the irrigation time with the conventional needle significantly effects the reduction of the bacterial count in the root canal.

Introduction: The aim of this study was to compare the cyclic fatigue resistance of ProTaper Universal, Twisted File Adaptive, Reciproc and WaveOne systems.
Materials and Methods: Four groups of nickel-titanium (Ni-Ti) endodontic instruments were tested in steel canals. The cyclic fatigue of the following Ni-Ti instruments was tested: ProTaper F2, Twisted File Adaptive ML 1, Reciproc R25 and WaveOne primary. The mean rpm of each system was evaluated in the testing block, and the number of cycles to failure was recorded for each instrument.
Results: The Reciproc had the highest fatigue resistance (p < 0.001) in the tested systems. There was no significant difference between the mean number of cycles to fracture of the WaveOne and the Twisted File Adaptive (p = 0.124), and the ProTaper Universal showed the least cyclic fatigue resistance (p < 0.001).
Conclusions: The latest Twisted File Adaptive system could not outclass tested instruments other than ProTaper Universal by means of the cyclic fatigue resistance.

The aim of this case report is to present treatment of a lateral incisor with severe bone destruction associated with a palatogingival groove by using endodontic-periodontal multidisciplinary approach. A palatogingival groove (PGG) is a predisposing factor for localized periodontal disease and is rare according to literature reports. It runs to various depths of the root surface of the involved tooth. This report describes the diagnosis and management of a left maxillary lateral incisor with a palatogingival groove extending below the middle third of the root with severe periodontal destruction. The tooth was treated with endodontic therapy and saucerization of the defect surface with resin-modified glass-ionomer cement (RMGIC) after a periodontal flap surgery. There was significantly decreased periradicular radiolucency and, periodontal attachment gain at the 24-month postoperative follow-up.

In dentistry, one of the most common situations that can result in the loss of teeth is periapical inflammation. The root canals provides a natural way for the spread of inflammation from the pulp into the periapical tissues. Microorganisms causing inflammation can spread very easily into the apical region with this passage. Initiation of acute or chronic inflammatory condition occurring in the apical region depends on the severity of the causative factor, the repetition over time and the host resistance. Chronic apical abscess is the conversion of acute apical abscess to the chronic phase through a periodontal gap and extra-oral sinus tract. This case report describes a patient who presented to our clinics with complaints of pain upon chewing and extra-oral swelling in the mandible. Healing occurred by endodontic and extra-oral surgical interventions.
Key words: Endodontic therapy, sinus tract, periapical lesion

Endo-perio lesion is a clinical dilemma and may be the most complex, refractory problem we encounter, even for the most experienced hands, and should not be underestimated. When a primarily endodontic pathology changes into a secondary periodontal lesion the clinical features become more unusual. This may delay the diagnosis and the correct treatment.
This case report evaluates 6 months follow up of non surgical endodontic retreatment of a endo – perio lesion which was treated before with conventional endodontic treatment and aims to show importance of obturation technique in lateral canals involved endo perio lesions.

Aim: The aim of this case report was to present the management of a periradicular lesion and the maintenance of pulp vitality following surgical odontoplasty in a maxillary lateral incisor with a palatogingival groove (PGG).
Summary: A case of PGG in the maxillary left lateral incisor with vital pulp and a large periradicular lesion is reported. Surgical odontoplasty of the PGG and restoration of the coronal part of the PGG were performed without root canal treatment. Follow-up revealed that the pulp responded to cold test in the same manner as prior to treatment and the periradicular lesion was resolved.
Conclusion: In cases where the apical pathosis includes the apical part of the root, the tooth should be evaluated using pulp vitality tests to determine whether the pulp is healthy. A tooth with vital pulp and periapical radiolucency should raise the suspicion of morphological changes, such as a PGG, in the tooth. A detailed examination of the tooth should be performed. Cone-beam computed tomography could be beneficial in making a definitive diagnosis.

This case report aims to present the management of a mandibular first molar with six root canals, four in mesial and two in distal root. A 16 year old male patient who has suffered from localized dull pain in his lower left posterior region for a long time was referred to the endodontic clinic. On clinical examination, neither caries lesion nor restoration was observed on the mandibular molar teeth; but the occlusal surface of the teeth had pathologic attrition. The mandibular and maxillary molars were tender to percussion due to bruxism, but there was no tenderness towards palpation. All of the molars revealed normal responses to the vitality tests. It was suggested that he should use the night-guard against bruxism. After three months, his pain almost completely relieved, but the percussion of the left mandibular molar was still going on. After access cavity preparation, careful examination of the pulp chamber floor with dental loupe and endodontic explorer (DG 16 probe) showed six canal orifices, four of mesially and two of distally. CBCT scan was performed in order to confirm the presence of six canals. Following one year, it was observed that he had no pain.