Comparison of two commercially available chlorhexidine mouthrinses: II. Effects on plaque reformation, gingivitis, and tooth staining.

Several chlorhexidine mouthwashes are now produced commercially but which differ in concentration and regimen of use. This study compared a 0.1% formulation with a 0.2% formulation for effects on plaque reformation, development of gingivitis, and tooth staining. The investigation was a single blind cross-over design employing 14 volunteers with a high standard of oral hygiene and gingival health. The rinses were used twice a day during two 19 day periods using the regiments recommended by each manufacturer and as a replacement for mechanical oral hygiene practices. A baseline zero plaque score was obtained at the beginning of each period with a 16-day washout allowed between the two periods. Parameters of gingival inflammation were scored at baseline and then, together with plaque and tooth stain scores, at 12 and 19 days. All indices of gingival inflammation and plaque were significantly increased at days 12 and 19 with the 0.1% mouthwash formulation. Little evidence of tooth staining was noted with the 0.1% formulation. The 0.2% mouthwash produced the characteristic staining noted with most chlorhexidine preparations. Based on the findings of this study and a previous laboratory investigation, it is concluded that the reduced antiplaque activity of the 0.1% formulation resulted from inactivation of chlorhexidine within the product rather than from the reduced dose of chlorhexidine used.