The effects of essential oil, povidone-iodine, and chlorhexidine mouthwash on salivary nitrate/nitrite and nitrate-reducing bacteria

Abstract

Dietary nitrate is reduced to nitrite and nitric oxide by microbial flora, and this activity is beneficial to vascular health. It has been reported that this bacterial process is inhibited by chlorhexidine mouthwash, although the effects of other products are largely unknown. This study examined the effects of several treatments on salivary nitrate/nitrite and nitrate-reducing bacteria. Twelve university staff and students performed mouth-washing with water (control), essential oil, 0.35% povidone-iodine, or 0.0025% chlorhexidine and then ate 100 g lettuce (110 mg nitrate content), followed by collection of saliva and tongue bacteria at the baseline, and 1, 5, and 10 h thereafter. The individual treatments were separated by an interval of one week. Salivary nitrate/nitrite was measured by the calorimetric method, and a representative nitrate-reducing bacterial species, Veillonella dispar, was detected and semi-quantified using a polymerase chain reaction (PCR) assay. Significant increases in salivary nitrate/nitrite were observed for all treatments (all P < 0.05). The PCR assay showed that water, essential oil, and povidone-iodine mouthwash had little effect, whereas V. dispar DNA bands were markedly inhibited after washing with chlorhexidine. These results suggest that essential oil and povidone-iodine mouthwash have little effect on oral nitrate-reducing activity. Salivary nitrite production was not reduced by chlorhexidine, but the fainter band of V. dispar DNA suggests that longer daily use might blunt this nitrate-reducing activity.

How Periodontal Disease and Presence of Nitric Oxide Reducing Oral Bacteria Can Affect Blood Pressure

“…The daily use of chlorhexidine mouthwash, even at a low concentration of 0.0025%, may reduce the count of Veillonella dispar and inhibit nitrate-reducing activity but it does not affect salivary nitrite production. Essential oil and povidone-iodine mouthwash has proven to have little effect on nitrate-reducing activity [ 73 , 74 ]. On the contrary, Senkus et al reported that 0.2% chlorhexidine mouthwash twice a day resulted in a significant reduction in salivary and plasma nitrite with a concomitant rise in salivary and plasma nitrate concentrations.…”

Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate

“…Although there is compelling evidence supporting the role of the tongue microbiome in the enterosalivary nitrate-nitrite-NO pathway, this remains a relatively unexplored area of human-microbial mutualism and many important questions must be addressed. Previous studies have demonstrated that nitrite-induced reductions in blood pressure are inhibited by antiseptic chlorhexidine (CHX) or other antibacterial mouthwashes (Tannenbaum et al, 1976; Govoni et al, 2008; Petersson et al, 2009; Kapil et al, 2013; McDonagh et al, 2015; Woessner et al, 2016; Mitsui and Harasawa, 2017). The focus of these studies has been from the perspective of cardiovascular physiology, and little information is available regarding the oral health status or habits of subjects in these studies.…”

Review of the Use of Nasal and Oral Antiseptics During a Global Pandemic

“…There is also concern that PVP-I may have unknown effects on the microbial flora of the oral cavity [23]. PVP-I showed no deleterious effect on a representative nitrate-reducing species called Veillonella dispar in the oral cavity suggesting it may not have an effect on the normal oral microbial flora [24].…”

“…A Listerine product consisting of eucalyptol 0.092%, menthol 0.042%, methyl salicylate 0.060% and thymol 0.064%, in 25% ethanol has been reported to have no detrimental effect to the representative nitrate-reducing bacteria V. dispar of the mouth [24]. No toxicity, or deleterious effects on the oral microbiota have been reported for occasional use.…”