Studies on the anatomy of the root apex are an area of interest to the endodontist; they have reported that the position of the apical constriction, apical foramen and the cemento-dentinal junction varies across the tooth types. These anatomical apical landmarks are considered extension limits for root canal instrumentation and filling. Achieving an optimum working length is thought essential for successful root canal treatment, so adopting any of these landmarks is associated with certain risks and benefits. The variability in the position of the apical constriction and apical foramen, for example, complicates their clinical detection, while the cemento-dentinal junction is a histological landmark that cannot be detected clinically. The radiographic apex does not always coincide with the anatomic apex of the tooth. The pre-operative status of the pulp must be considered while obtaining the working length. Most prognostic studies agree that extending the root filling to within 2-3 mm of the radiographic apex is associated with favorable treatment outcomes.

Objectives: This article investigates the internal and external morphological variability of mandibular premolars along with clinical and radiographical signs that leads to early identification of these cases. Materials and Methods: The authors identified articles by searching the PubMed, Medline and Scopus databases. Inclusion criteria were case reports of mandibular premolars with aberrant internal and external anatomy, articles that describe the origin of anatomy of mandibular premolars, the traits that may influence their external and internal variability through species revolution and articles of new technologies like cone beam computed tomography that help the diagnosis of difficult cases. Results: In the majority of the cases, mandibular premolars are reported to have one root canal running a single root. On the other hand, anatomic irregularities in this group of teeth, such as the existence of more than one root or more than one root canals or even a more complicated root canal system cannot be considered infrequent as it appears in 10-25% of the cases. Conclusion: Successful endodontic treatment of mandibular premolars is a challenge for the clinician as they often present morphological and anatomical abnormalities.

Aim: Smear layer removal from artificially prepared internal root resorption (IRR) cavities using the self-adjusting file (SAF) system with activated continuous irrigation or the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) with conventional syringe/needle irrigation was compared. Materials and methods: Twenty-eight maxillary central incisors were selected, decoronated and 20 of them were randomizedly splited along the coronal plane into labial and lingual sections, and artificial IRR cavities were prepared in both walls. Tooth segments were rejoined and teeth were divided into two groups. Each group (n = 10) was prepared using the SAF or ProTaper system with 12-mL 5.25% NaOCl and 12-mL 17% EDTA. Root canals were prepared in six intact positive control teeth using the SAF or ProTaper system with 5.25% NaOCl and 17% EDTA. As negative controls, two intact teeth were prepared using NaOCl only. Roots were than split longitudinally from the rejoined segments and samples were evaluated under scanning electron microscopy using a five-point scoring system. Results: Most SAF (87%) and ProTaper (83%) samples (P > 0.05), had scores of 1 and 2 indicating clean canal walls for the IRR cavities. Conclusions: SAF with activated continuous irrigation and ProTaper with conventional syringe/needle irrigation both successfully removed the smear layer from artificially prepared IRR cavities

Aim: The purpose of this study was to investigate procedural errors occurring during conventional root canal treatment performed by undergraduate students attending two dental schools in Riyadh, Saudi Arabia. Materials and Methods: A cross-sectional survey was distributed to 600 undergraduate dental students from the Riyadh Colleges of Dentistry and Pharmacy (RCsDP) and the College of Dentistry at King Saud University (KSU) in Riyadh, Saudi Arabia. Participants were senior male and female dental students from the 4 ^th to 6 ^th years at RCsDP and the 4 ^th to 5 ^th years at KSU. Participants were asked to record their endodontic mishaps; these data were analyzed using IBM SPSS software. Chi-square (X² ) tests were carried out to compare pairs of groups; significance was established at 5% (p < 0.05). Results: The percentage of endodontic mishaps was 68%. The majority of students who made endodontic mishaps were male (73.6%) (X² =8.74, =0.002). Most mishaps occurred in the posterior area (63.96%) and those with curved roots (39.46%). Conclusion: The frequency of endodontic mishaps occurring at both schools was found to be higher in 4 ^th year students from KSU, but this dramatically decreased in the 5 ^th year. Variable results were obtained from the RCsDP 4 ^th year students, but they did not improve in the 5 ^th and 6 ^th year. We believe that the use of step-down techniques utilizing flexible nickel titanium files and more training in the lab will cause potentially fewer procedural complications at both schools.

Swallowing or aspiration of dental instruments and objects can occur in every field of dentistry. These instruments and objects vary in sizes, shapes and quality which make it difficult to locate their position. Gastro scope is a versatile instrument used in both diagnostic as well as interventional surgical procedures. This report emphasizes on the important of using rubber dam during root canal treatment and the use of gastroscope as an emergency procedure when the swallowed instrument has been located in stomach; to prevents further complications.

One of the causes of non-healing periapical pathosis in endodontically treated tooth is root perforation. This can occur pathologically by resorption and caries, iatrogenically during endodontic therapy (zip, strip, furcal perforations). Root perforation results in bacterial contamination, periradicular tissue injury, inflammation, and bone resorption. The purpose of this case report is to describe endodontic retreatment and surgical management of a longstanding periapical lesion on maxillary lateral incisor, associated with perforation and osseous defects using mineral trioxide aggregate (MTA). Although the majority of bone support and root dentin was damaged, an attempt was made to repair the defect and restore the tooth. After the surgical intervention and root canal treatment, the perforation was subsequently sealed with MTA. Later, the root was reinforced with composites and the tooth was restored with direct veneer. Conclusion: Four-and-a-half year (54 months) recall examination showed no evidence of periodontal breakdown, no symptoms of further deterioration, and complete healing of periradicular lesions when examined by radiography. This case report presents a treatment strategy that could improve the healing process and beneficial outcomes for patients with perforation and osseous defect.