Determination of antimicrobial activity in formulations applied to Endodontics

In Dentistry, the different methodologies used in the antimicrobial evaluation of chemicals substances in vitro can explain the difficulties encountered in the scientific reproduction. Objectives: As objective, the following experiment aimed at determining the antimicrobial activity, according to the International protocol of analysis, in 2 formulations: carbamida peroxide 10% in carbopol gel (formulation 1) and carbamida peroxide 10% in carbowax (cream) (formulation 2), applied to the endodontic therapy. Filter paper disks were impregnated in increasing concentrations which were determined after several attempts, considering the 2 formulations being tested, solubilized in sterile destiled water. The microorganisms used ( strains ATCC) were: S.aureus,E.coli, P.aeruginosa, M.luteus, E.faecalis e C.albicans. Methods: The antimicrobial susceptibility testing followed the Kirby and Bauer method, according to the protocol M100-S13/2003 from the NCCLS. Results: The results were given in millimeters which refer to the halo of each disk, and were obtained after an avarage of 10 readings. Both formulations present microbiological activity when they are in contact with the strains in question. In both formulations the results of inhibition (halos in millimeters) followed the increasing concentrations, but different in the 300µg concentration. Conclusions: The formulation 1 presented greater inhibition when in contact with the strains in question than formulation 2. The results are not correlated to sensitivity or resistence from the NCCLS parameters and the methods can be reproducible.