Antibiotics against Periodontal Biofilms.

The systemic administration of antibiotics in conjunction with mechanical biofilm disruption results in reduced numbers of subgingival periodontal pathogens and improved clinical outcomes. Penicillins, tetracyclines, macrolides, quinolones, and nitroimidazoles were used in laboratory and clinical studies. The current literature was reviewed and studies investigating the effect of antibiotics on periodontal pathogens in biofilm models or in clinical trials were analyzed. While there is only a limited number of in vitro studies, numerous clinical studies reported microbiological outcomes. The combination of amoxicillin and metronidazole seems to provide superior antimicrobial effects when used in biofilm models or in clinical trials. In vitro studies using biofilm models showed that antibiotics alone have only limited effects on the bacterial load in biofilms but might be effective in reducing specific species. These results imply that mechanical biofilm disruption is indicated to allow antibiotics to be effective. Clinical trials also demonstrated that the combination therapy of amoxicillin and metronidazole might result in more superior microbiological effects than amoxicillin or metronidazole alone. The results of clinical studies investigating azithromycin are contrary. While it seems to be appropriate to use in chronic periodontitis (comparable to the new classification: stage 3 or 4, grade B generalized periodontitis), there was no superior effect observed in aggressive periodontitis (comparable to the new classification: stage 3 or 4, grade C generalized periodontitis). Doxycycline cannot be recommended for chronic periodontitis (stage 3 or 4, grade B) patients. Antibiotics as drugs come with side effects. Common adverse effects of antibiotics are opportunistic yeast infection and gastrointestinal complications (e.g., nausea, diarrhea, and colitis). The development of resistance suggests a role for microbiological analysis and antibiotic susceptibility testing in the selection of systemic periodontal antibiotic therapy.