Rom J Morphol Embryol 2016, 57(1):153–159 ISSN (print) 1220–0522 ISSN (online) 2066–8279 ORIGINAL PAPER An optical investigation of dentinal discoloration due to commonly endodontic sealers, using the transmitted light polarizing microscopy and spectrophotometry IOANA SUCIU 1) , ECATERINA IONESCU 2) , BOGDAN ALEXANDRU DIMITRIU 1) , RUXANDRA-IOANA BARTOK 3) , GEORGIANA-FLORENTINA MOLDOVEANU 1) , IRINA-MARIA GHEORGHIU 3) , ILEANA SUCIU 1) , MIHAI CIOCÎRDEL 4) 1) Department of Endodontics, Faculty of Dental Medicine, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania 2) Department of Orthodontics, Faculty of Dental Medicine, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania 3) Department of Restorative Dentistry, Faculty of Dental Medicine, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania 4) Department of Geology, Petroleum–Gas University of Ploiesti, Romania Abstract The aim of this study was to establish the degree of tooth crown staining by commonly used endodontic sealers. Crown discolorations by tooth canal sealers [AH Plus (Dentsply DeTrey Gmbh, Konstanz, Germany); Endofill (Produits Dentaires SA, Vevey, Switzerland); Apexit (Dentsply DeTrey Gmbh, Konstanz, Germany); and MTA Fillapex (Angelus, Londrina, Brazil)] were tested on extracted human premolars. The samples were divided into five groups of five samples each, after root canal sealing. Five teeth were used as control groups. The spectrophotometric method was performed in order to quantify in terms of color change of the coronal part (it was also recorded a track on how the color changes over time). For the microscopic study of the extracted dental specimens subjected to this study, polarized transmitted light microscopy was used. This method involves the development of special microscopic preparations, called “thin sections”. In our case, the thin section was performed on 20 prepared and obturated recently extracted teeth. The degree of discoloration was determined after one week and three months using spectrophotometry and polarized light microscopy. All sealers usually cause some degree of discoloration on the cervical aspect of the crowns that increases in time. AH Plus and Endofill caused the greatest discoloration, followed by Apexit and MTA Fillapex. Keywords: sealer, crown discoloration, spectrophotometry, polarized light microscopy.  Introduction Discoloration of the coronal dental structure represents a major esthetic problem and one of the most common reasons for which patients come to the dentist [1]. The causes of the dentinal discoloration are various ones and there were classified into extrinsic and intrinsic causes [2, 3]. Extrinsic discoloration is caused by the extrinsic agents that act upon the external structures of the tooth. These agents, colored or not, determine color changes in the dentin, as spots or as a whole [4]. The most common agents involved in extrinsic discoloration are: a poor oral hygiene, with an excess of dental plaque and calculus, coffee, tea, other beverages or tobacco colorations [5], drugs used for a longer period of time (Tetracycline, Minocycline, Doxicycline, Chlorhexidine, iron-based drugs) [6–9], etc. Intrinsic discoloration is more commonly caused by dental caries, pulp pathology or endodontic treatments. There are various factors that may lead to the tooth color change (discoloration) after endodontic treatments; most often, this process occurs due to endodontic material penetration during the dentinal tubules treatment [10, 11]. Due to an anesthetic aspect, about 28% of the adult population in Great Britain [12] and 34% of the USA population [13] are not satisfied with their teeth color. Starting from the premise that the dentin is considered a permeable medium for the tooth, it would be expected to find variable distribution of sealing components used for root canal filling, at distance from the pulp chamber, or the root canals [14–16]. As a first step, it is therefore appropriate the microscopic detection of the physical substrate of visible color changes, since the macroscopic appearance of the tooth is given at least in part by the phenomena of light passing through transparent media (i.e., enamel). Transmitted light microscopy shows the changes of a beam of light passing through the specimen (a thin section of this), while other imaging methods commonly used in histological studies on teeth, such as stereo reflective and scanning electron microscopy (SEM) only provides some details of the morphology of the studied surfaces. In this study, the aim was to detect the presence of coronary plaque color changes and the dentin distribution of sealing components using the spectrophotometry and polarized transmitted light microscopy. In addition, the aim of this study was to demonstrate the discoloring effect on teeth crowns of some commonly endodontic sealers used in the endodontic treatment.  Materials and Methods Twenty recently extracted human premolars with R J M E Romanian Journal of Morphology & Embryology http://www.rjme.ro/