ORIGINAL RESEARCH Root canal filling quality of mandibular molars with EndoSequence BC and AH Plus sealers: A micro-CT study Rafael Nigri Roizenblit 1 ; Fabiola Ormiga Soares 1 ; Ricardo Tadeu Lopes 2 ; Bernardo Camargodos Santos 2 ; and Heloisa Gusman 1 1 Department of Dental Clinic, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil 2 Department of Nuclear Instrumentation Laboratory, Technology Center, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil Keywords bioceramics, mandibular molars, micro- computed tomography, root canal filling, root canal sealers. Correspondence Professor Heloisa Gusman, Rodolpho Paulo Rocco 325 / 2° andar, Ilha da Cidade Universit aria, Rio de Janeiro 21941-913, Brazil. Email: heloisa.gusman@odonto.ufrj.br doi: 10.1111/aej.12373 (Accepted for publication 30 August 2019.) Abstract The aim of this study was to compare, by micro-computed tomography (mi- cro-CT) analysis, the obturation quality of two filling methods: the single-cone technique with the bioceramic EndoSequence BC sealer and the continuous wave technique with the resin-based AH Plus sealer. Twenty mandibular molars were divided into two groups (n = 10) according to the sealer used. Only the mesial roots, which are known to have mostly two canals, were used. The specimens were scanned before and after instrumentation and after obtu- ration. Root canal volume after instrumentation and filling volume were cal- culated to obtain the percentage volumes of filling, voids and gaps. All specimens presented final volumes that were smaller than the initial volumes (P < 0.05). There was no significant difference between groups for filling vol- ume, voids and gaps (P > 0.05). Using two filling methods, EndoSequence BC and AH Plus promoted a similar root filling quality in mesial roots of mandibu- lar molars. Neither sealer was able to fill the root canal system completely. Introduction Endodontic obturation is an essential step in endodontic treatment; it is aimed at sealing the root canal system, preventing future bacterial contamination or recontami- nation (1). The anatomic complexity of the root canal system, characterised by the presence of irregularities, ramifications and isthmuses, presents a challenge during endodontic treatment (2). Typically, the obturation con- sists of a dense core, such as gutta-percha, covered with a sealer for the best adaptation to the root canal walls (3). Sealers can fill root canal irregularities, dentinal tubules and ramifications that are not filled by gutta-percha (4). Endodontic sealers can interact with dentine physically and chemically. The physical interaction is established by penetration of the material inside dentinal tubules, creat- ing mechanical retentions. The chemical interaction is characterised by the formation of tags along the sealer– dentine interface (5). The epoxy resin-based sealers, such as AH Plus sealer (Dentsply DeTrey Gmbh, Konstanz, Germany), can bond to dentin; AH Plus sealer also has antimicrobial activity against Enterococcus faecalis, is bio- compatible, has good flow and has long-term dimensional stability (6). Tricalcium silicate-based mate- rials, such as mineral trioxide aggregate (MTA)-based sealers and bioceramic sealers, form an interfacial layer with tag-like structures at the cement–dentin interface, which increases the push-out bond strength of these materials (5). Bioceramics were introduced in endodontics as root repair cements (7,8) and root canal sealers (9,10). Pre- mixed calcium silicate-based endodontic sealers stand out from the bioceramic root canal sealers, as they have good physicochemical and biological properties, with results similar or better than conventional endodontic sealers (11). EndoSequence BC (FKG, La Chaux-de-Fonds, Switzerland) is one such sealer that contains zirconium oxide, calcium silicates, calcium phosphate, calcium hydroxide and thickening agents (10); has antimicrobial properties; is biocompatible, radiopaque and chemically stable; and does not shrink after setting (11). The bioceramic sealers EndoSequence and Smartpaste Bio have been demonstrated as being more effective than AH Plus and ActiV GP when used with the single-cone technique to fill the apical third of single root canal teeth ((12–14)). © 2019 Australian Society of Endodontology Inc 1 Aust Endod J 2019