Prognostic Indicators for 2-phase Antimicrobial Periodontal Therapy

Objectives: To prospectively identify clinical, microbiological and/or biological markers as prognostic indicators for success of a 2-phase antimicrobial non-surgical and surgical periodontal therapy.
Methods: Randomized, placebo controlled and double-masked clinical trial with a 12-months follow-up. 80 patients with chronic or aggressive periodontitis received periodontal treatment supplemented with 375 mg amoxicillin plus 500 mg metronidazole, 3/d for 7 days, either during the first, non-surgical, or the second, surgical, phase. Clinical measurements, peak values of 15 cytokines and 9 acute-phase proteins in serum and five selected microorganisms were evaluated before, during and after therapy. Potential predictive variables were tested for association with the primary outcome: presence of at least one site with probing depth (PD) >4mm and bleeding on probing (BOP) at 12 months after therapy, using first univariable, then multivariable logistic regression.
Results: At baseline, there were no significant differences between groups for any of the studied parameters. Giving the AB during the first or second phase yielded similar long term clinical microbiological and biological results. The univariable analysis including all studied parameters, revealed that the plaque Index score at 3 months (odds ratio=6.53, P= 0.09) and the levels of Parviromonas micra (PM) at baseline (odds ratio= 3.79, P= 0.03) had the most significant effect for predicting the presence of at least one site with PD>4mm and BOP+ at the12 month follow-up visit. The significance of PM was further enhanced (odd ratio=4.32, p= 0.003) in the multivariable analysis when factors, such as sex, diagnosis of chronic vs aggressive periodontitis and levels of Prevotella intermedia were included. Overall, these parameters yielded moderate accuracy (area under the curve: 0.74) for predicting the treatment outcome.
Conclusions: Microbiological diagnostics of PM before treatment may have a predictive value on response to periodontal therapy.