Background: The aim of this study is to evaluate the effects of metronidazole-amoxicillin combination on clinical and microbiologic parameters in patients with generalized aggressive periodontitis.
Methods: Twenty-eight patients were randomly included. The test group (n = 12) received amoxicillin-metronidazole combination and scaling and root planing; the control group (n = 16) received scaling and root planing alone. In addition to the clinical examinations, subgingival plaque samples were analyzed for total cultivable bacteria and the presence of Porphyromonas gingivalis, Tannerella forsythia (previously T. forsythensis), Treponema denticola, Prevotella intermedia, Prevotella nigrescens, Prevotella pallens, and Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) using polymerase chain reaction.
Results: All clinical parameters improved significantly compared to baseline (P <0.05) in both groups. There was a statistically significant reduction of pockets and clinical attachment gain in the combined group compared to the control group (P <0.05). Total counts of bacteria also decreased significantly at 3 and 6 months in both groups (P <0.05). T. denticola and T. forsythia were the most prevalent bacteria throughout the study. T. denticola showed a continuous decrease over 6 months in the test group, whereas no change was seen in the control group beyond 3 months. P. gingivalis decreased significantly at 3 months (P <0.05), whereas T. forsythia was the only pathogen decreased below detection limits by the combination therapy with a significant difference compared to the control group (P <0.05).
Conclusions: The results from this study suggest that combined amoxicillin and metronidazole use as an adjunct to scaling and root planing leads to better clinical healing compared to mechanical treatment alone. The polypharmaceutical approach used results in a significant and substantial decrease in T. forsythia and prevents its recolonization for 6 months, suggesting that T. forsythia may determine the long-term stability of periodontal treatment outcomes.