Concentration of metronidazole in periodontal pockets after application of a metronidazole 25% dental gel

The metronidazole concentration was monitored in gingival crevicular fluid (GCF) of inflamed periodontal pockets after 1 application of a 25% gel. 12 patients with periodontal disease were included in the study. Metronidazole gel was applied with a syringe into the pockets of 10 teeth with probing depths > or = 5 mm. Samples of GCF were taken with Periopaper before application and 4, 8, 12, 24 and 36 h after application. At each time, samples from 2 teeth were pooled in order to obtain a sufficient amount of fluid for analysis. By means of a calibrated Periotron, the collected volume of GCF was measured. High-performance liquid chromatography was used to determine the amount of metronidazole. MIC50 for anaerobic periopathogens susceptible to metronidazole is below 1 microgram/ml. In this study, the concentration obtained was higher than 1 microgram/ml in all samples after 4 and 8 h, in 92% after 12 h, in 50% after 24 h and in 8% after 36 h. Thus, metronidazole concentrations in the pockets were generally above MIC50 for susceptible periopathogens 24 h after 1 application of a 25% metronidazole gel.