Background: The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) remains equivocal, and it is not known whether the use of adjunctive antibiotics may enhance the effect of FDIS. The aim of the present study is to test the hypothesis that there is no difference in the 1-year clinical outcome of therapy among groups of patients treated with conventional SRP performed over 2 to 3 weeks, or same-day FDIS, with or without adjunctive metronidazole.
Methods: A total of 184 patients with moderate-to-severe periodontitis were randomly allocated to one of four treatment groups: 1) FDIS+metronidazole; 2) FDIS+placebo; 3) SRP+metronidazole; or 4) SRP+placebo. Recordings of plaque, bleeding on probing, probing depth (PD), and clinical attachment level (CAL) were carried out in four sites per tooth at baseline and at 3 and 12 months after treatment.
Results: No differences were observed in the mean CAL or PD values between the four experimental groups at baseline and 3 or 12 months post-treatment. All four groups displayed significant improvements in all parameters. However, using absence of pockets ≥5 mm as the criterion for treatment success, the two groups receiving adjunctive metronidazole performed significantly better than the two placebo groups.
Conclusion: Metronidazole had a significant, adjunctive effect in patients with a metronidazole-sensitive subgingival microbiota on the clinical parameters of CAL, PD, and absence of pockets ≥5 mm.