Bioactive glass with antimicrobial agents : in vitro evaluation.

Abstract

Bioactive glass is biocompatible and has the ability to stimulate bone formation. The aim of the present study was to evaluate the efficiency of bioactive glass in releasing tetracycline and/or hydrocortisone through an in vitro growth inhibition study involving microorganisms commonly found in the oral cavity: Staphylococcus aureus (ATCC 27664), Enterococcus faecalis (ATCC 12399) and Streptococcus mutans (ATCC 70069). The bioactive glass was prepared using the sol-gel method and had a molar composition of 80% SiO2, 4% P2O5 and 16% CaO. Four groups were formed: a drug-free control group (CG); a hydrocortisone group (HG) with 2% (in weight) of the drug incorporated into the bioactive glass; a tetracycline group (TG) containing 2% (in weight) of the drug; and a hydrocortisone-tetracycline group (HTG) containing 2% of each drug. Test specimens were distributed in Petri dishes containing agar previously inoculated with the microorganisms and incubated for 24 hours. Statistical analysis involved the Kruskal-Wallis and Mann-Whitney tests. The CG and HG proved ineffective in inhibiting the growth of the microorganisms. The TG exhibited inhibition zones on all microorganisms tested. The HTG had the largest inhibition zones for Staphylococcus aureus (ATCC 27664) and Enterococcus faecalis (ATCC 12399), with statistically significant differences in comparison to the other groups (p < 0.001). The present study demonstrates that bioactive glass is able to release tetracycline for effective antibiotic action.