Antibiotic therapy as an adjunct to scaling and root planing in smokers


It has long been established that smoking is a significant modifying factor in the progression of periodontal disease and eventual tooth loss (Dietrich et al. 2015; Zeng et al. 2014). The established treatment of periodontal disease is based on the elimination of pathogens through subgingival scaling and root planing (SRP), if periodontal disease remains following this initial ‘hygienic phase’ then treatment can be repeated with the addition of systemic antibiotics too good effect (Keestra et al. 2014; Rabelo et al. 2015). Thus, the aim of this study is to conduct a systematic review and meta-analysis to evaluate the effectiveness of systemic antibiotic therapy associated with periodontal treatment in smokers.


This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement with the focused question; “Do adjunctive antimicrobials improve the clinical outcome of non-surgical therapy (scaling and root planing [SRP]) in the treatment of periodontitis in smokers?”

The following inclusion criteria were applied:  Randomized controlled clinical trials; studies published in English; studies with smoker patients (at least 10 cigarettes per day for at least five years) diagnosed with chronic periodontitis; patients without significant systemic diseases ; aged between 30 and 70 years; not receive periodontal treatment in the last six months; used systemic antibiotic therapy associated with periodontal treatment; present the results of the test and control groups, and  assessments of clinical periodontal parameters such as probing depth (PD), bleeding on probing (BOP) and clinical attachment level (CA). Exclusion criteria were local antibiotic therapy and trials not published in English.

Two researchers independently selected and screened the articles. Data bases were searched from July 1994 to August 2016. The included databases were MEDLINE, Cochrane Controlled Clinical Trial Register, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, CINAHL, Science Direct, and ISI Web of Knowledge, Scopus, and manually searched relevant specialist journals. Quality assessment was undertaken using the Jadad scale.


The systematic Search found 3 papers out of 68 which fulfilled the inclusion criteria for meta-analysis. On the JADAD risk of bias assessment only 8/30 studies were evaluated as high quality.

Meta-analysis results (Primary outcomes)

Mean Difference Probing Depth (p = 0.0359   MD -0.32,   95% CI -0.50 – -0.14)
Mean Difference Clinical Attachment level (p = 0.0161   MD -0.22,   95% CI -0.39 – -0.06)
Mean Difference Bleeding on Probing (p = 0.446     MD -0.04,   95% CI -0.13– 0.06)

 Author’s Conclusion

“The results of our meta-analysis reveal the clinical benefits of systemic antibiotics as an adjunct to the non-surgical periodontal treatment of smokers. These clinical improvements, although statistically significant, appeared to be of little clinical relevance.”


In the discussion, the author goes to considerable length to explain the effectiveness for the adjunctive use of antibiotics in the periodontal treatment of smokers and to their credit also the lack of clinical relevance. There are three important points to be made here:

  • The degree of precision in the published mean difference of this paper is 0.005mm. The maximum precision possible with a standard periodontal probe is 0.5mm, and in the surgery the measurements are mostly taken as whole numbers. Mosteller described the issue this way:

“The number of significant figures gives a hint of accuracy. For example, 98.2o has three significant figures and might be regarded as correct to within 0.05o (One should not count on this level of accuracy.) Therefore, in these ambiguous circumstances, the author should tell what degree of accuracy is intended, as nearly as possible”(Mosteller 1992)


  • It is not an uncommon finding in primary research that the test groups and the trials time-frame are far too small to derive any precise/useful statistical results; this is something authors need to be addressed at the planning and protocol registration stage.


  • Additionally in the primary research the subjects continued to smoke throughout the duration of the trial, therefore it is hardly surprising there is no improvement in the results, the damaging effect of the smoking drowning out the benefit of the antibiotics. It is generally accepted that tobacco smoking remains the leading single risk to health in high-income North America and Western Europe by quite a large margin. (Lim et al. 2012).


Primary Paper

Assem, N.Z. et al., 2017. Antibiotic therapy as an adjunct to scaling and root planing in smokers: a systematic review and meta-analysis. Brazilian Oral Research, 31, pp.1–15. Available at:

Additional references

Dietrich, T. et al., 2015. Smoking, Smoking Cessation, and Risk of Tooth Loss: The EPIC-Potsdam Study. Journal of dental research, 94(10), pp.1369–75.

Keestra, J.A.J. et al., 2014. Non-surgical periodontal therapy with systemic antibiotics in patients with untreated chronic periodontitis: A systematic review and meta-analysis. Journal of Periodontal Research, (32), pp.689–706.

Lim, S.S. et al., 2012. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: A systematic analysis for the Global Burden of Disease Study 2010. The Lancet, 380(9859), pp.2224–2260.

Mosteller, F., 1992. Writing about numbers. In Medical uses of statistics. Boston: NEJM Books, pp. 375–89.

Rabelo, C.C. et al., 2015. Systemic antibiotics in the treatment of aggressive periodontitis. A systematic review and a Bayesian Network meta-analysis. Journal of Clinical Periodontology, 42(7), pp.647–657.

Zeng, J. et al., 2014. Reexamining the Association Between Smoking and Periodontitis in the Dunedin Study With an Enhanced Analytical Approach. Journal of Periodontology, 85(10), pp.1390–1397. Available at:





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