Dental caries is a disease in which bacteria ferment carbohydrates, which produces acids and breaks down tooth mineral.1,2 These cariogenic bacteria are acidogenic (acid-forming) and aciduric (tolerate a highly acidic environment), and include Streptococcus mutans, Streptococcus sobrinus, and lactobacilli.3–5 The removal of plaque and reduction of cariogenic bacteria are key to preventing tooth decay. Mouthrinses are an important adjunct to reducing cariogenic bacteria in the oral cavity, secondary to the mechanical removal of plaque through toothbrushing and interproximal cleaning.
Reducing cariogenic bacteria is integral to maintaining oral health. S. mutans—which describes seven streptococcal groups found in the oral cavity—is found in high quantities in the plaque biofilm associated with carious lesions, and is also more aciduric than other oral bacteria in the Streptococcus species.6–8 S. mutans tolerates a highly acidic environment, allowing it to further the progression of caries. S. sobrinus uses glucose for acid production more rapidly than S. mutans and is more cariogenic than S. mutans.9,10 Lactobacilli depend on S. mutans to colonize in the oral cavity through the creation of a “retentive niche.”11 A low pH environment and exposure to fermentable carbohydrates are then all that is needed for lactobacilli to colonize and further the progression of carious lesions.
THE USE OF MOUTHRINSES
Different ingredients in mouthrinses can reduce cariogenic bacteria. In a study on the antimicrobial efficacy of mouthrinses containing chlorhexidine, sodium fluoride, fluoride with essential oils, alum, green tea, and garlic with lime, results showed that chlorhexidine was the most effective against S. mutans and lactobacilli, followed by the garlic with lime mouthrinse.12 However, the garlic with lime mouthrinse needs more scientific evaluation. The study also showed that green tea and alum mouthrinses were less effective in reducing cariogenic bacteria than the other mouthrinses tested but still showed inhibitory effects on S. mutans and lactobacilli.12
The effect of mouthrinses containing essential oils, chlorhexidine, benzethonium chloride, and povidone-iodine on cariogenic bacteria were studied by Oyanagi et al.13 Results showed that the rinses containing essential oils and chlorhexidine were highly successful in eliminating significant numbers of planktonic bacteria and bacteria enmeshed within biofilms. The essential oil mouthrinse also demonstrated inhibitory capabilities that helped to prevent demineralization.
Tehrani et al14 conducted a study comparing sodium fluoride mouthrinses with green tea mouthrinses. Results showed that both mouthrinses were effective in reducing the colony counts of S. mutans and lactobacilli. The difference between the two mouthrinses was in their mechanisms of action. Sodium fluoride prevents S. mutans from adhering to the tooth structure, inhibits demineralization, and remineralizes incipient carious lesions.15 Green tea polyphenols inhibit the growth of S. mutans, S. sobrinus, and lactobacilli, and prevent S. mutans from attaching to the tooth structure.16–18 Green tea mouthrinses may be a good option in reducing cariogenic bacteria, but they do not remineralize incipient carious lesions, as sodium fluoride does.15 Sodium fluoride mouthrinses are contraindicated in children younger than 6 age due to the risk of ingestion.19
In a study comparing povidone-iodine and chlorhexidine mouthrinses, children at high-caries risk were divided into three groups following restorative treatment: the first group received the 1% povidone-iodine mouthrinse, the second group received the 0.2% chlorhexidine mouthrinse, and the third group received the placebo mouthrinse.20 All groups showed significant reductions in S. mutans immediately after mouthrinse therapy, with higher reductions seen among the first group. Unfortunately, after 15 days, 30 days, and 90 days, S. mutans counts in all three groups increased, demonstrating a short duration of efficacy.
Additional studies found that the inclusion of povidone-iodine in mouthrinses significantly reduced S. mutans when applied in 3-month intervals over 1 year.21,22 Using the mouthrinses for short periods and introducing them again in a few months may keep the bacterial count down over a longer duration. To reduce the bacterial count even further, 7.5% povidone-iodine mouthrinses can be used, followed by 0.2% chlorhexidine mouthrinses.23 Contraindications to povidone-iodine mouthrinses include sensitivities to iodine and any pre-existing thyroid disorders.24
A study conducted on children with high-caries risk showed a significant reduction in S. mutans using both chlorhexidine mouthrinses and sodium fluoride mouthrinses.25 Chlorhexidine is known as the gold standard in reducing cariogenic bacteria, while sodium fluoride is considered the gold standard of caries prevention.12,14,26 However, patient compliance with chlorhexidine mouthrinses may be low due to the taste, staining of teeth, and risk of taste alteration.26–29
A review of the literature regarding the effects of cetylpyridinium chloride (CPC) showed that CPC is effective in plaque control, reducing gingivitis, and reducing gingival bleeding.31–34 An article comparing mouthrinses with CPC and sodium fluoride revealed that CPC-containing test rinses with and without fluoride were both highly bactericidal against S. mutans.35 The results showed that fluoride did not reduce the antibacterial efficacy of CPC, nor did CPC reduce the efficacy of fluoride in inhibiting demineralization.35
Mouthrinses containing chlorine dioxide may also decrease plaque scores. In a study conducted on mouthrinses containing aloe vera, chlorine dioxide, and chlorhexidine, both the chlorhexidine and chlorine dioxide rinses caused significant reduction of plaque scores. The study authors suggest that chlorine dioxide may be a suitable alternative for chlorhexidine but more research is indicated.36
Xylitol also provides plaque-reducing qualities. In a study that investigated mouthrinses containing chlorhexidine, xylitol, and a combination of chlorhexidine and xylitol against S. sanguis and S. mutans, results showed the combination of xylitol and chlorhexidine was most effective against the cariogenic species.37
The use of mouthrinses is an important adjunct to mechanical removal of plaque, as some ingredients have been found to reduce the prevalence of S. mutans. Dental hygienists should stay up to date on the benefits of different ingredients in mouthrinses in order to educate their patients on the most effective mouthrinses to reduce the cariogenic load in their patients’ oral cavities. Incorporating mouthrinse recommendations and directions into oral hygiene instructions can improve patient health, along with the appropriate toothbrushing and interproximal cleaning technique. Evaluating the effectiveness of certain ingredients on the reduction of cariogenic bacteria will aid in the creation of mouthrinses that can reduce these bacteria with fewer side effects.
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- Marsh P, Martin M. Oral Microbiology. 4th ed. Oxford: Wright, 1999.
- Marsh P. The role of chemostats in the evaluation of antimicrobial agents for use in dental products. Microb Ecol in Health and Dis. 1993;6:147–149.
- Hamada S, Slade H. Biology, immunology, and cariogenicity of Streptococcus mutans. Microb Rev. 1973;44:331–384.
- Loesche W. Role of Streptoccocus mutans in human dental decay. Microb Rev. 1986;50:353–380.
- Hanada N. Current understanding of the cause of dental caries. JpJ J Infect Dis. 2000;53:1–5.
- Minah G, Loesche W. Sucrose metabolism in resting-cell suspensions of caries-associated and non-caries-associated dental plaque. Infect Immun. 1977;17:43–54.
- Donoghue H, Tyler J. Antagonisms amongst streptococci isolated from the human oral cavity. Arch Oral Biol. 1975;20:381–387.
- de Soet J, Toors F, de Graaff J. Acidogenesis by oral streptococci at different pH values. Caries Res. 1989;23:14–17.
- de Soet J, van Loveren C, Lammens A, et al. Differences in cariogenicity between fresh isolates of Streptococcus sobrinus and Streptococcus mutans. Caries Res. 1991;25:116–122.
- Caufield PW, Schön CN, Saraithong P, Li Y, Argimón S. Oral lactobacilli and dental caries. J Dent Res. 2015;94(9 Suppl):110S–118S.
- Thomas A, Thakur S, Mhambrey S. Comparison of the antimicrobial efficacy of chlorhexidine, sodium fluoride, fluoride with essential oils, alum, green tea, and garlic with lime mouth rinses on cariogenic microbes. J Int Soc Prev Community Dent. 2015;5:302–308.
- Oyanagi T, Tagami J, Matin K. Potentials of mouthwashes in disinfecting cariogenic bacteria and biofilms leading to inhibition of caries. Open Dent J. 2012;6:23–30.
- Tehrani M, Asghari G, Hajiahmadi M. Comparing Streptococcus mutans and Lactobacillus colony count changes following green tea mouth rinse or sodium fluoride mouth rinse use in children (randomized double-blind controlled clinical trial). Dent Res J. 2011;8(Suppl 1):S58–563.
- Kukreja B, Dodwad V. Herbal mouthwashes: a gift of nature. Int J Pharma Bio Sci. 2012;3:46–52.
- Watson P, Pontefract H, Devine D, et al. Penetration of fluoride into natural plaque biofilms. J Dent Res. 2005;84:451–455.
- Hassani A, Amirmozafari N, Ordouzadeh N, Hamdi K, Nazari R, Ghaemi A. Voltatile components of Camellia simensis inhibit growth and biofilm formation of oral Streptococci in vitro. Pak J Biol Sci. 2008;11:1336–1341.
- Otake S, Makimura M, Kuroki T, Nishihara Y, Hirasawa M. Anticaries effects of polyphenolic compounds from Japanese green tea. Caries Res. 1991;25:438–443.
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- Neeraja R, AnantharaJ A, Praveen P, Karthik V, Vinitha M. The effect of povidone-iodine and chlorhexidine mouth rinses on plaque Streptococcus mutans count in 6- to 12-year-old school children: an in vivo study. J Ind Soc of Pedod and Prev Dent. 2008;26:14–18.
- Adamietz I, Rahn R, Bottcher H, Schafer V, Reimer K, Fleischer W. Prophylaxis with povidone-iodine against induction of oral mucositis by radiochemotherapy. Support Care Cancer. 1998;6:373–377.
- Simratvir M, Singh N, Chopra S, Thomas A. Efficacy of 10% Povidone Iodine in children affected with early childhood caries: an in vivo study. J Clin Pediatr Dent. 2010;34:233–238.
- Zhan L, Featherstone J, Gansky S, et al. Antibacterial treatment needed for severe early childhood caries. J Public Health Dent. 2006;66:174–179.
- Shin A, Nam S. The effects of various mouthwashes on the oral environment change for oral health care. Biomed Res. 2018;29:1724–1729.
- Sundas S, Rao A. Comparative evaluation of chlorhexidine and sodium fluoride mouthwashes on streptococcus mutans. J Nep Dent Assoc. 2011;12:17–21.
- Mathur S, Mathur T, Srivastava R, Khatri R. Chlorhexidine: the gold standard in chemical plaque control. Natl J of Physiol, Pharm & Pharmacol. 2011;1:45–50.
- Parwani S, Parwani R, Chitnis P, Dadlani H, Prasad S. Comparative evaluation of anti-plaque efficacy of herbal and 0.2% chlorhexidine gluconate mouthwash in a 4-day plaque regrowth study. J Indian Soc Periodontol. 2013;17:72–77.
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- Flotra L, Gjermo P, Rolla G, Waerhaug J. Side effects of chlorhexidine mouthwashes. Scand J Dent Res. 1971;79:119–125.
- Mankodi S, Bauroth K, Witt J, et al. A 6-month clinical trial to study the effects of a cetylpyridinium chloride mouthrinse on gingivitis and plaque. Am J Dent. 2005;18 Spec No:9A–14A.
- Witt J, Walters P, Bsoul S, Gibb R, Dunavent J, Putt M. Comparative clinical trial of two antigingivitis mouthrinses. Am J Dent. 2005;18 Spec No:15A–17A.
- Kozak K, Gibb R, Dunavent J, White D. Efficacy of a high bioavailable cetylpridinium chloride mouthrinse over a 24-hour period: A plaque imaging study. Am J Dent. 2005;18 Spec No:18A–23A.
- Watanabe E, Tanomaru J, Nascimento A, Matoba-Junior F, Tanomaru-Filho M, Yoko I. Determination of the maximum inhibitory dilution of cetylpyridinium chloride-based mouthwashes against Staphylococcus aureus: an in vitro study. J Appl Oral Sci. 2008;16:275–279.
- Wu C, Savitt E. Evaluation of the safety and efficacy of over-the-counter oral hygiene products for the reduction and control of plaque and gingivitis. Periodontol 2000. 2002;28:91–105.
- Latimer J, Munday J, Buzza K, Forbes S, Sreenivasan P, McBain A. Antibacterial and anti-biofilm activity of mouthrinses containing cetylpyridinium chloride and sodium fluoride. BMC Microbiology. 2015;15:169.
- Yeturu SK, Acharya S, Urala AS, Pentapati KC. patented pH+ technology to neutralize acidic oral pH. J Oral Biol Craniofac Res. 2016;6:54–58.
- Decker EM, Maier G, Axmann D, Brecx M, von Ohle C. Effect of xylitol/chlorhexidine versus xylitol or chlorhexidine as single rinses on initial biofilm formation of cariogenic streptococci. Quintessence Int. 2008;39:17–22.
From Dimensions of Dental Hygiene. November 2019;17(10):18—20.