Biocompatibility of New Calcium Aluminate Cement (EndoBinder) Fabiano Gamero Aguilar, DDS, MSc, Lucas Fonseca Roberti Garcia, DDS, MSc, PhD, and Fernanda Carvalho Panzeri Pires-de-Souza, DDS, MSc, PhD Abstract Introduction: The purpose of this study was to evaluate the biocompatibility of calcium aluminate cement (Endo- Binder) in subcutaneous tissue of rats. Methods: Fifteen rats, weighing 300 g, were separated into 3 groups (n = 5) in accordance with the time of death (7, 21, 42 days). Two incisions were made in the dorsal subcutaneous tissue of each rat in which were im- planted 2 polyethylene tubes filled with the test mate- rials, EndoBinder (EB) and Grey MTA (GMTA). The external tube walls were considered the negative control group (CG). After 7, 21, and 42 days, animals were killed, obtaining 5 samples per group, at each time interval of analysis. Results: From the morphologic and morphometric analyses by using a score of (0–3) (50, 100, and 400), results showed absence of inflam- matory reaction (0) for EB after 42 days. However, for GMTA, a slight inflammatory reaction (1) was observed after 42 days, which means the persistence of a chronic inflammatory process. When compared with CG, tissue reaction ranging from discrete (1–7 days) to absent (0–42 days) was observed. Conclusions: EndoBinder presented satisfactory tissue reaction; it was biocompat- ible when tested in subcutaneous tissue of rats. (J Endod 2012;38:367–371) Key Words Biocompatibility, calcium aluminate cement, mineral trioxide aggregate, tissue reaction C ements routinely used in endodontic therapy are applied in intimate contact with periapical tissues and must therefore present adequate biological compatibility (1). Among these cements, mineral trioxide aggregate (MTA) is outstanding. It was originally developed as a material for retrograde filling and treatment of root and furca perforations (2, 3), but because of its good clinical performance and biocompatibility (1, 2) it has been used in various other situations, among them pulp capping (4) and pulpotomy (5). MTA is composed of Portland cement (75 wt-%), Bi 2 O 3 (20 wt-%), and dehy- drated CaSO 4 (5 wt-%). Portland cement, in turn, is constituted by SiO 2 (21.2 wt- %), CaO (68.1 wt-%), Al 2 O 3 (4.7 wt-%), MgO (0.48 wt-%), and Fe 2 O 3 (1.89 wt-%). In the manufacturing process, they are proportioned and heated up to 1600  C to obtain a powder composed of 3CaO.SiO 2 , 2CaO.SiO 2 , 3CaO.Al 2 O 3 , and 4CaO.Al 2 O 3 .Fe 2 O 3 . Gypsum (CaSO 4 .4H 2 O) is then added to control the setting time of the cement (1, 2). MTA is capable of inducing reparative hard tissue formation on exposed pulp in addition to promoting greater dentin bridge formation than materials previously used for this purpose (6, 7). Studies have reported that in humans, the pulp repair process is induced in a more effective manner by MTA than by calcium hydroxide, which is known to cause inflammation initially and necrosis of the area close to the exposure (7–9). The repair process promoted by MTA begins during hydration of the material, when calcium disilicate and trisilicate react with water to form calcium hydroxide and hydrated calcium silicate gel, producing an alkaline pH (10). Calcium ions are then released and diffused through dentinal tubules so that their concentration increases as the setting time of the material passes (11). In spite of the recognized reparative capacity of MTA, some negative characteristics of the material must be taken into consideration, such as the long setting time, which makes it difficult to apply (12, 13); difficulty with manipulating it, which makes it highly unstable and compromises its mechanical properties (14, 15); low flow capacity (2); and high rate of dental structure staining (16, 17). These points justify the development of new dental materials that have adequate mechanical properties and are biologically compatible (18). Therefore, a new calcium aluminate–based endodontic cement (patent number PI0704502-6, 2007), called EndoBinder (Binderware, S ~ ao Carlos, SP, Brazil), has been developed, with the intention of preserving the properties and clinical applications of MTA without its negative characteristics. EndoBinder is produced by the process of calcining Al 2 O 3 and CaCO 3 at temperatures between 1315  C and 1425  C. The calcium aluminate formed is cooled and triturated until a suitable particle size is obtained with high levels of purity (19), eliminating traces of free MgO and CaO, which are responsible for the undesired expansion of the material (20), and Fe 2 O 3 , which is responsible for tooth darkening (16, 17). Bismuth oxide (20 wt-%) is then added to the material to guarantee sufficient radiopacity (21), in accordance with ISO specification 6876 (22). It is known that this material presents adequate physical and mechanical properties (15) and good cell response, allowing greater development of cells at an advanced state of osteoblastic differentiation than obtained with MTA (23). However, there are no data with regard to inflammatory response to the material in connective and pulp tissues. From the Department of Dental Materials and Prosthodon- tics, Ribeir~ ao Preto School of Dentistry, University of S~ ao Paulo, Ribeir~ ao Preto, S~ ao Paulo, Brazil. Address requests for reprints to Professor Fernanda Car- valho Panzeri Pires-de-Souza, Faculdade de Odontologia de Ribeir~ ao Preto (USP), Departamento de Materiais Dent arios e Pr otese, Avenida do Caf e, s/n, Bairro Monte Alegre, 14040- 904 Ribeir~ ao Preto, SP, Brazil. E-mail address: ferpanzeri@ forp.usp.br 0099-2399/$ - see front matter Copyright ª 2012 American Association of Endodontists. doi:10.1016/j.joen.2011.11.002 Basic Research—Technology JOE — Volume 38, Number 3, March 2012 Biocompatibility of New Calcium Aluminate Cement 367