Non-surgical periodontal treatment with and without adjunctive metronidazole in smokers and non-smokers

Aim: To determine whether adjunctive metronidazole therapy would compensate for the poorer treatment response to scaling and root planing reported in smokers. Method: A single-blind, randomised clinical trial of 28 smokers an d 56 non-smokers, stratified for periodontitis disease severity and randoml y allocated to 3 treatment groups: (1) Scaling and root planing using an ul trasonic scaler with local anaesthesia (SRP), (2) SRP+metronidazole tabs 20 0 mg tds for 7 days, (3) SRP+2 subgingival applications of 25% metronidazol e gel. Probing depths (PD) and attachment levels (AL) were recorded with a Florida probe at baseline, 2 months and 6 months post treatment by a single examiner who was unaware of the treatment modality. Results were analysed for all sites with baseline probing depths equal to or grater than Florida probe recordings of 4.6 mm using analysis of variance. Results: Reductions in probing depth at 6 months were significantly less (p<0.001) in the smoke rs (mean 1.23 mm, 95% confidence intervals = 1.05 to 1.40 mm) than in the n on-smokers (1.92, 1.75 to 2.09 mm). Attachment level gains were approximate ly 0.55 mm and there was no statistically significant difference between sm okers and non-smokers. There were no differences in any clinical measure in response to the three treatment regimens at 2 or 6 months for either smoke rs or non-smokers. A reduction in the proportion of spirochaetes was observ ed at 6 months which was less in smokers than in nonsmokers (p=0.034). Mult iple linear regression analysis on probing depth at 6 months demonstrated t hat smoking was a significant explanatory factor (p<0.001) for poor treatme nt outcome, whilst the presence or absence of adjunctive metronidazole was not (p=0.620). Conclusion. This study confirms that smokers have a poorer t reatment response to SRP, regardless of the application of either systemic or locally applied adjunctive metronidazole.