Clinical and microbiological benefits of strict supragingival plaque control as part of the active phase of periodontal therapy

Abstract

Aim: To compare the clinical and microbiological effects of scaling and root planing (SRP) alone or combined with mechanical [professional plaque control (PPC)] or chemical [chlorhexidine rinsing (CHX)] control of supragingival plaque in the treatment of chronic periodontitis.

Material and methods: Sixty subjects were randomly assigned to receive SRP alone or combined with PPC (twice a week) or with CHX rinsing (twice a day). The adjunctive treatments began with SRP and were continued for 42 days. Clinical and microbiological examinations were performed at baseline, 2 and 6 months post-therapy. Subgingival plaque samples were analysed for 38 bacterial species by checkerboard DNA-DNA hybridization.

Results: The two test treatments were more effective in improving probing depth and clinical attachment level (CAL) than SRP alone, even in intermediate and deep sites. CAL gain was better maintained in the CHX group. The most beneficial microbiological changes were observed in CHX-treated subjects, who showed a significant reduction in the proportions of red and orange complexes, as well as an increase in the proportions of the host-compatible bacterial species.

Conclusion: Strict plaque control performed during and after SRP improves periodontal treatment outcomes. The greatest microbiological and clinical benefits were observed with the use of CHX rinsing.

Figure 1

Flow chart of the study design.

Figure 2

Bar charts of the mean changes (±SD) in full-mouth probing depth, clinical attachment level and percentage of sites with bleeding on probing between baseline and 2 or 6 months post-SRP in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The whiskers represent the SD. The significance of difference among the three treatment groups for each clinical parameter was assessed using the Kruskal-Wallis test. Subsequently, the significance of difference within pairs of groups was assessed using the Mann-Whitney U-test (different letters indicate p<0.05). SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.

Figure 3

Bar charts of the mean changes (±SD) in probing depth, clinical attachment level and percentage of sites with bleeding on probing at sites with initial probing depth ≤ 3, 4∓6 and ≥ 7 mm between baseline and 2 or 6 months post-SRP in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The whiskers represent the SD. Significance testing is as described in Fig. 2. SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.

Figure 4

Plots of the mean changes in individual full-mouth mean clinical attachment level between baseline and 6 months post-SRP of subjects in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The circles represent the mean value of each subject. The dashed line represents the median of change of this clinical parameter in all 60 subjects. Positive values represent a gain in clinical attachment level (CAL), while negative values represent a loss in CAL at 6 months post-SRP. SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.

Figure 5

Mean counts (×10⁵) of the 38 test species at baseline, 2 and 6 months post-SRP in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The species were ordered according to the microbial complexes described by Socransky et al. (1998). Counts of individual species were averaged within a subject and then across subjects in each treatment group at each time point. The significance of differences between baseline and 6 months post-SRP was assessed using the Wilcoxon test (* p<0.05), and adjusted for 38 comparisons (Socransky et al. 1991). SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.

Figure 6

Mean percentage of DNA probe counts of the 38 test species at baseline, 2 and 6 months post-therapy in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The species were ordered according to the microbial complexes described by Socransky et al. (1998). The proportion that each species comprised of the total DNA probe count was determined at each site, and then averaged within and across subjects in each treatment group at each time point. The significance of differences between baseline and 6 months post-SRP was assessed using the Wilcoxon test (* p<0.05), and adjusted for 38 comparisons (Socransky et al. 1991). SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.

Figure 7

Pie charts of the mean proportion of each microbial complex at baseline, 2 and 6 months post-SRP in the three treatment groups. Subjects in the SRP and SRP+PPC groups rinsed with placebo. The colors represent different microbial complexes (Socransky et al. 1998). The significance of differences between baseline and 2 months, and baseline and 6 months was assessed using the Wilcoxon test (* p<0.05). The significance of differences among treatment groups at baseline, at 2 and at 6 months post-therapy was assessed using the Kruskal-Wallis and Mann-Whitney U-test (different letters indicate p<0.05). SRP: Scaling and root planing; PPC: Professional plaque control; CHX: Chlorhexidine rinsing.