Summary of article “Differences in antimicrobial activity of four commercial 0.12% chlorhexidine mouthrinse formulations: an in vitro contact test and salivary bacterial counts study”

Authors: Herrera D, Roldán S, Santacruz I, Santos S, Masdevall M, Sanz M.

Journal: J Clin Periodontol. 2003 Apr; 30(4): 307-14.

Chlorhexidine (CHX) is considered the gold standard antiseptic due to its proven anti-plaque and anti-gingivitis effects. How it is formulated is the key to whether or not it will exert high reactivity, and by replacing alcohol with other compounds, its activity can be affected. The aim of this study was to assess the antimicrobial activity of four mouthrinse solutions with different chlorhexidine formulations in vitro and in vivo.

The four studied mouthrinses included one containing 0.12% CHX + 5% alcohol, one containing 0.12% CHX + 0.05% cetylpyiridinium chloride (CPC), one containing 0.12% CHX alone and another containing 0.12% CHX + sodium fluoride, the latter three without alcohol. A negative saline control was also used.

The in vitro study consisted of a dual contact test (SIKT) on the 4 mouthrinses and on the negative control for 20 individual dissolutions using each of the most common oral bacterial species in health and in disease. The in vivo study consisted of instructing ten students to rinse with each one of the products, followed by saliva sampling before and 5 and 7 hours after rinsing. Culture plate bacterial counts were performed in both studies, and statistical analyses were performed based on the results expressed in CFU.

The results for the in vitro study showed differences between the 4 CHX mouthrinses and the negative control, although only CHX combined with CPC yielded a total absence of bacterial resistance. Similarly, the results for the in vivo study showed differences between the 4 CHX mouthrinses and the negative control, and the mouthrinses containing CHX + alcohol and CHX + CPC obtained greater survival percentages for anaerobic bacteria in the first few hours after their use.

Both for the in vivo study and for the in vitro study, not only the formulation containing alcohol, but also the one containing CPC, proved to provide superior microbiological control-related outcomes. Thus, it was found that the fact that a mouthrinse contains chlorhexidine is not enough to ensure its efficacy, and that the entire formulation of a product is very important. It is worth mentioning that both when alcohol is removed and when anionic compounds such as sodium fluoride are added, a mouthrinse’s activity decreases. The addition of cetylpyridinium chloride to a CHX mouthrinse provides a safe and effective option for the microbiological control of pathogenic biofilm growth in the oral cavity, without the potential adverse effects that alcohol can cause.