The effect of polyvinyl pyrrolidone on the clinical activity of 0.09% and 0.2% chlorhexidine mouthrinses

Background: Previous studies have shown that polyvinyl pyrrolidone (PVP) ad ded to a chlorhexidine rinse reduced extrinsic dental stain but at the expe nse of a reduction in plaque inhibitory activity. This effect appeared due to a reduction in the effective chlorhexidine dose to levels where dose res ponse studies show plaque inhibition falls off rapidly. The aim of these 2 clinical studies was to determine if PVP could be added to chlorhexidine ri nses to maintain efficacy and reduce staining. Method: Study 1 involved 42 healthy dentate volunteers and was a blind, ran domised, 7 treatment, crossover design balanced for residual effects. The r inses were: 1. 0.09% chlorhexidine to which was added, 2. 1% PVP, 3. 3% PVP , 4. 5% PVP, 5. 7% PVP 6. Placebo, 7. Essential oil product. Rinses were us ed 2X on day one of each period after a prophylaxis. Subjects suspended too th cleaning for 24 h and were then scored for plaque area. Study 2 used the experimental gingivitis model, involved 24 healthy dentate subjects and wa s a blind, randomised, 3 treatment, crossover design balanced for residual effects. The rinses were 1. 0.2% chlorhexidine, 2. 0.2% chlorhexidine/10% P VP, 3. Placebo. At baseline and the end of each study period subjects were rendered plaque, stain and calculus free, suspended oral hygiene and rinsed 2X per day. Plaque, gingivitis and stain were scored at baseline, 1, 2, an d 3 weeks. Calculus was scored at baseline and 3 weeks. Results: Study 1: Buccal plaque scores were significantly lower with all ri nses compared to placebo. Also all buccal plaque scores were significantly lower with chlorhexidine and chlorhexidine/PVP rinses compared to the essen tial oil/phenolic rinse. There were no significant differences between the chlorhexidine rinse and the chlorhexidine/PVP rinses. Analyses for buccal a nd lingual plaque combined produced, with one exception, the same results f or rinse comparisons as for buccal plaque alone. Thus the essential oil/phe nolic rinse just failed to reach significance compared to placebo. Study 2: Plaque and gingivitis scores were significantly lower with positive contro l and test rinses compared to placebo but with no difference between these rinses. Tooth and tongue stain was significantly higher with the positive c ontrol and test rinses compared to placebo but not significantly different between these 2 rinses. Calculus scores were not significantly different be tween the three study rinses. Conclusion: Taken with previous data, the balance of evidence does not supp ort PVP as an inhibitor of staining associated with chlorhexidine. These da ta are further evidence that chlorhexidine oral hygiene products, which, do not or claim not to cause staining, are most probably lacking efficacy.