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Objeticve: The aim of this study was to develop a composite material with antibacterial activity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMA matrix and added low concentration of MMT/CHX. The aim was to evaluate the drug release capacity of MMT, and not to provide reinforcement., Methods: Six experimental composites were made with organic matrix of BisGMA/TEGDMA in equal proportions by weight. The composites received organophlizated montmorillonite with or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion (DC) was evaluated using FTIR (peak 6165 cm-1; n=5). Specimens for flexural properties (10×2×1mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS) was measured using the three point bending test (n=10). Inibition halo was used to test the antibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonas gingivalis (n=5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated by inserting polymerized disc of composite in to a culture media colonized with Streptococcus mutans (n=10). The release of CHX was measured using ultraviolet (255nm) for 10 days (n=5). The data of degree of conversion was analysed using Kruskal-Wallis/ Mann-Whitney, and the other variables using two-way ANOVA/Tukey, always considering a global level of significance of 5%., Results: DC ranged from 71% to 74%. E ranged from 5.7 to 8.1GPa. FS ranged from 61.4 to 74.7MPa. There were no statistical differences among the groups for all the variables. For the three bacteria tested the composites with CHX loaded presented inhibition of growth for all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BF was lower for the groups with 10% MMT/CHX, all groups presented BF, even those without CHX loaded. All concentrations presented release off CHX during all the 28 days analyzed., Conclusions: Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated., (Copyright © 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)