Chronic periodontitis: Efficacy of adjunctive antimicrobials

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Periodontitis is a common chronic oral health problem contributing to the global health burden with the US Centers for Disease Control and Prevention (CDC) estimating that 47% of adult over 30 have some form of periodontitis.  Its origin is multifactorial involving pathogenic bacterial flora and genetic predisposition. Scaling and root planing aiming to remove local irritating factors is the mainstay of treatment as this does not eliminate all pathogenic bacteria systemic antibiotics have been used as an adjunct.

The aim of this review analysis was to assess the efficacy of antimicrobials adjunctive to scaling and root planing (SRP) in the treatment of chronic periodontitis.


Searches were conducted in the Medline/PubMed, Cochrane Controlled Clinical Trial Register (CENTRAL) and Embase databases with no date or language restriction. This was supplemented by hand searches of the journals, Journal of Periodontology, Journal of Clinical Periodontology, Journal of Dental Research, Journal of Periodontal Research, Journal of the American Dental Association, and Clinical Oral Investigations. Randomised controlled trials (RCTs) comparing SRP alone or with placebo versus SRP and any systemic antimicrobial.

Two reviewers independently screened and selected studies and extracted data with risk of bias being assessed with the Cochrane risk of bias tool (RoB 2.0).  The main outcomes were full-mouth pocket depth reduction and clinical attachment level gain at 6 and 12 months. Mean differences (MD) and standard deviations were calculated for clinical attachment level (CAL) gain and probing depth (PD) reduction at 6 and 12 months. A network meta-analysis was performed to assess direct and indirect comparisons and to establish a ranking of treatments


  • 21 studies involving a total of 1344 patients were included.
  • 2 studies were considered to be at high risk of bias, 8 at low risk and 11 at unclear risk.
  • 9 different antimicrobials with a wide dosage and duration ranges were used.
  • 15 studies reported a statistically significant difference in PD reduction and CAL gain in favour of adjunctive systemic antibiotics when compared to SRP alone.
  • Results from network meta-analysis were similar to those retrieved by pairwise meta-analysis.
  • Network meta-analysis showed that SRP + amoxicillin (AMX) + metronidazole (MTZ), compared to SRP, provided the highest PD reduction and CAL gain at 6 and 12 months (see table).

Network Meta-analysis findings (significant values only).  

  PD reduction

Mean Difference (95%CI)

CAL gain

Mean Difference (95%CI)

SRP + AMX + MTZ v SRP – 6 months 0.47 (0.30; 0.64) 0.54 (0.27; 0.80)
SRP + AMX + MTZ v SRP – 12 months 0.51 (0.25; 0.78) 0.37 (0.05; 0.69)
SRP + MTZ v SRP – 6 months 0.13 (0.00; 0.25) 0.15 (0.00; 0.30)
SRP + MTZ v SRP – 12 months 0.19 (0.07; 0.32) 0.18 (0.01; 0.35
SRP + AMX + MTZ v SRP + MTZ – 6 months 0.34 (0.14; 0.53) 0.38 (0.11; 0.65)
SRP + AMX + MTZ v SRP + AZM – 6 months 0.37 (0.17; 0.58) 0.51 (0.21; 0.82)
SRP + AMX + MTZ v SRP + AZM – 12 months 0.38 (0.06; 0.67) 0.37 (0.01; 0.72)

AZM, Azithromycin


The authors concluded: –

The findings of this systematic review revealed that amoxicillin and metronidazole was the best additional treatment in the nonsurgical treatment of chronic periodontitis. However, future studies are needed to clarify the efficacy of other antimicrobials.


We recently considered a Cochrane review of adjunctive antimicrobials for non-surgical periodontal treatment (Dental Elf – 23rd Nov 2020). That review included 45 RCTs compared with the 21 studies in the current review, 9 of which were not included in the Cochrane review. The Cochrane review also included several other antimicrobials. This topic is one is where they have been large number of systematic reviews published, the Cochrane review highlighting 10 other systematic reviews published between 2014 and 2020 with this review adding yet another. Given the time required to undertake a systematic review this large number of reviews represents a considerable duplication of effort. While a number of the reviews demonstrate a statistically significant improvement with antibiotic use there is the important question of whether this is clinically important. Consequently, the Cochrane review highlighted a clear need to define a minimally important clinical difference for commonly reported periodontal outcomes. This together with well conducted better reported RCTs which include reporting of adverse events are needed.


Primary Paper

Sgolastra F, Petrucci A, Ciarrocchi I, Masci C, Spadaro A. Adjunctive systemic antimicrobials in the treatment of chronic periodontitis: A systematic review and network meta-analysis. J Periodontal Res. 2021 Apr;56(2):236-248. doi: 10.1111/jre.12821. Epub 2020 Dec 12. PMID: 33314159.

Review protocol in PROSPERO

Other references

Dental Elf – 23rd Nov 2020

Periodontitis: Systemic antimicrobials as an adjunct to non-surgical treatment



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