Effectiveness of Antimicrobial Adjuncts to Scaling and Root Planing Therapy for Periodontitis

Arthur J. Bonito AJ, Lohr KN, Lux L, Sutton S, Jackman A, Whitener L, Evensen C. Effectiveness of Antimicrobial Adjuncts to Scaling and Root Planing Therapy for Periodontitis Vol. 2. Evidence Tables. Evidence Report/Technology Assessment No. 88 (Prepared by RTI International-University of North Carolina Evidence-based Practice Center under Contract No. 290-97-0011) AHRQ Publication No. 04-E014-3. Rockville, MD: Agency for Healthcare Research and Quality. March 2004.




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This systematic review concerns chronic periodontitis (bacterial infections of the soft tissue and bone supporting the teeth), which affects many adults in the United States, some severely enough to threaten loss of teeth. The key question is whether, in adults with chronic periodontitis, scaling and root planing (SRP) accompanied by an adjunctive antimicrobial agent when compared to SRP alone improves outcomes that persist over time. Adjunctive antimicrobials include systemic and/or locally applied tetracycline, minocycline, metronidazole, metronidazole plus amoxicillin, chlorhexidine, a grouping of other antibiotics, and a grouping of other antimicrobials. Primary outcomes are reductions in probing depth (PD), gains in clinical attachment level (CAL), and decreases in selected pathogens, especially spirochetes.

Data Sources

The RTI-UNC Evidence-based Practice Center did a series of MEDLINE searches covering 1966 through December 2002 and an EMBASE search through February 2002 to identify published primary research on this key question; we conducted hand searches of relevant leading journals and used literature identified by clinical experts that the searches did not identify.

Selection Criteria

We included clinical trials published in English that (a) involved adults with chronic periodontitis but no serious comorbidities, (b) tested one or more chemical antimicrobial agents as an adjunct to SRP alone (or with a placebo), (c) had a concurrent control group that received the same SRP as the treatment group, (d) reported outcomes for specified, fixed time periods, and (e) if multiple antimicrobials were tested, reported outcomes for each agent separately.

Data Collection and Analysis

From a pool of nearly 11,000 articles, we retained 599 for independent dual reviews; we retained 70 of these articles, although we used some more than once because they involved more than one antimicrobial arm. A single abstractor abstracted data that were then entered into evidence tables; at least one author independently confirmed data in the evidence tables against original articles and verified data in text and text tables. We did descriptive and qualitative syntheses of this evidence, focusing on the PD, CAL, and microbiological outcomes, mainly percentage change in spirochetes, reported for the longest time period of each trial. We conducted several meta-analyses of PD and CAL effect sizes when we had necessary data on at least three studies at 6-month follow-up (plus or minus 3 months).

Main Results

Findings differed markedly by antimicrobial and mode of delivery. While this literature has numerous limitations, locally administered adjunctive drugs appear to be more efficacious than systemic drugs; most positive results occurred for tetracycline, minocycline, metronidazole, and chlorhexidine. Adjunctive therapies generally reduced PD levels; differences between treatment and SRP-only groups in the baseline-to-follow-up changes typically favored treatment groups but usually only modestly (e.g., from about 0.1 mm to nearly 0.5 mm) even when the differences between groups were statistically significant. Effects for CAL gains were smaller and statistical significance less common.


Some antimicrobials show promise as adjunctive therapies to SRP for treating non-aggressive chronic periodontitis in patients without other comorbid conditions such as diabetes or immune deficiency, but the marginal improvements in PD and CAL are a fraction of the improvements from SRP alone. Thus, whether such improvements, even if statistically significant, are clinically meaningful remains a question. A substantial agenda of future research to address that and other issues (e.g., costs, patient-oriented outcomes) remains.