Nano science and nanotechnology have revolutionized all aspects in the endodontic field. The aim of the present study was to describe the application of nanotechnology in endodontics by reviewing the literature. Application of nanomaterials, with a smaller size, for surface modification has reduced the incidence of failure in the rotary nickeltitanium files. Nanoparticles with the ability of rapid dispersion into the hard-to-reach spaces in the complex Root Canal system have a better antimicrobial effect. The incorporation of nanoparticles in the obturating materials promotes the sealing properties and antimicrobial efficacy. Nanoscaffolds in the pulp regeneration approaches, bioceramics as retrofilling, and repair materials, and Nanorobots and nanoterminators as new technologies for local anesthesia with fewer side effects are some examples in this regard.

Background: Endodontic treatment is one of the stress producing situations.Objectives: The purpose of this article was to determine the most stressful stage of Root Canal Therapy among endodontists, endodontic residents, and undergraduate dental students and offering some strategies for reducing stress during this treatment.Patients and Methods: This descriptive survey comprised three groups. Thirty-six endodontists, 41 endodontic residents, and 47 undergraduate dental students selected by convenience sampling. Participants were asked about age, sex, the most stressful stage of Root Canal Therapy and stress reducing strategies during the procedure.Results: The most stressful stage of Root Canal Therapy was endodontic treatment for children in male endodontists and residents, preparing access cavity on crowns in female endodontists, obturation of apically Root Resorped Canals in female residents, obturation in female students, and preparing access cavity on molar teeth in male students. The most suggested strategy for reducing stress during Root Canal Therapy was related to experience, knowledge, enough study, and technical mastery.Conclusions: It is required to consider the strategies during student education in dental schools for both under and postgraduation dental students and better to follow them in workshops for other dentists and even endodontists.

A mandibular first molar reqiring Root Canal Therapy was found with five Canals, three mesial canls, and two distal Canals. Initially, four Canals (mesiobuccal, mesiolingual, distobuccal, and distolingual were identified. The mesiobuccal and mesiobuccal and mesiolingual Canals were found in their normal locations, and a fifth Canal was noted between these two. This case demonstrates a rare anatomical configuration and supplements previous reports of the existence of such configurations in mandibular first molars.