IntroductionRadix entomolaris presents with an unusual morphology and is a rare occurrence. It is mainly observed in mandibular first molars. The incidence varies in different populations but it is far from common. This is especially true for mandibular second molars which possess the lowest prevalence. Some case reports have shown the presence of this finding in mandibular second molars; however, cases of patients of a white background have not been reported.Case presentationThe diagnosis and treatment of an infected radix entomolaris in a mandibular second molar in a 45-year-old white man is presented. The diagnosis was made with standard endodontic techniques. Conventional radiographic imaging was augmented with cone-beam computed tomography scans and three-dimensional images which were constructed with dedicated software. The endodontic treatment was done using accepted endodontic procedures. Clinical and radiographic evidence of healing was seen after a 14-month follow-up.ConclusionsThe implications of complex and unpredictable root anatomy are discussed in this report. The clinician should consider the possibility of encountering a mandibular second molar with a radix entomolaris. Cone-beam computed tomography is a useful tool in the diagnosis and improvement of root canal therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s13256-015-0681-x) contains supplementary material, which is available to authorized users.

Recently, filling materials have been introduced based on the dentine adhesion technologies used in conservative dentistry in an attempt to seal the root canal more effectively. The purpose of this study was to investigate the interface between the canal and root-filling material. Sealing ability of four root canal obturation methods was analysed by means of scanning electron microscopy. Extracted single-rooted teeth were endodontically treated and filled with gutta-percha/Pulp Canal Sealer using the Thermafil (TH) technique, gutta-percha/Pulp Canal Sealer using the System B (SB) technique, Resilon points/RealSeal (RS) and RealSeal 1/RealSeal (RS1). Specimen interfaces were analysed using field-emission scanning electron microscopy. The adhesive groups RS and RS1, formed hybrid layers but showed areas of separation (gaps) similar to those in the conventional obturation groups. The RS and RS1 groups showed less separation in the coronal third, but the separation was similar to that in the TH and SB groups in the middle and apical thirds. The sealing ability of Resilon is not superior to that of existing materials.

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