Clinical and Microbiologic Effects of Adjunctive Metronidazole Plus Amoxicillin in the Treatment of Generalized Chronic Periodontitis: Smokers Versus Non-Smokers

Background: The aim of the present study is to evaluate the clinical and microbiologic effects of the adjunctive use of metronidazole (MTZ) and amoxicillin (AMX) in the treatment of smokers and non-smokers with generalized chronic periodontitis (CP). Methods: Thirty-two smokers and 32 non-smokers were selected and received scaling and root planing (SRP) combined with MTZ (400 mg three times daily) and AMX (500 mg three times daily) for 14 days. Clinical and microbiologic examinations were performed at baseline and 3 months after SRP. Nine subgingival plaque samples per patient were analyzed using checkerboard DNA-DNA hybridization. Results: Both groups presented a significant improvement in all clinical parameters at 3 months after therapy (P < 0.05). Non-smokers showed lower mean number of sites with probing depth (PD) 5 mm after therapy. Fewer non-smokers exhibited at least nine of these sites at 3 months after treatment. Non-smokers also presented the greatest reductions in mean PD and gain in clinical attachment between baseline and 3 months after therapy at initially deep (PD 7 mm) sites (P < 0.01). The most beneficial changes in the microbial profile were also observed in the non-smoker group, which showed the lowest proportions of the orange complex at 3 months, as well as a significant increase in the proportions of Actinomyces species after treatment. Conclusion: Smokers with CP benefit less than nonsmokers from treatment by the combination of SRP, MTZ, and AMX.