The Role of Mouthrinses in Biofilm Control

Dental caries and periodontal diseases are ongoing public health issues across the globe. In the United States, approximately two out of every five adults have some form of periodontal disease.¹ The oral cavity hosts more than 700 types of bacteria/​​pathogens.² The byproducts of these pathogens promote the initial attachment to the acquired pellicle, triggering biofilm formation and colonization, which can damage hard tissues and irritate soft tissues.³

The initial attachment and growth of biofilm depend on nutrients from saliva, but the conditions surrounding the teeth and oral structures impact the production and maturation of biofilm.³ Additionally, the formation of mature biofilm colonies relies on a type of bacterial communication known as quorum sensing.³

Creating Personalized Oral Hygiene Regimens

Depending on the extent of biofilm present and the severity of oral diseases, the dental professional should be prepared to create appropriate individualized oral hygiene regimens. The most common method of biofilm removal is toothbrushing and flossing. These methods are technique-dependent and may be especially difficult for individuals with various limitations such as difficult-to-reach areas, regions of high biofilm accumulation, physical disabilities, cognitive challenges, and dexterity issues.⁴ The overall outcome of the dental hygiene therapy, whether prophylaxis or scaling and root planing, may have a more favorable prognosis with the application of targeted adjunctive therapies as part of daily biofilm disruption. However, rinsing with any therapeutic agent does not penetrate deep periodontal pockets among individuals with advanced stages of periodontal diseases.

The use of mouthrinse as an adjunct to daily oral hygiene is a simple, cost-effective, and beneficial method for enhancing oral health.⁴ Based on the patient’s specific oral healthcare needs and risk for disease, the dental professional should be able to recommend therapies effective in targeting and preventing plaque-biofilm formation.⁴ The most researched therapeutic ingredients that specifically target biofilm are chlorhexidine (CHX), essential oils, fluoride, and cetylpyridinium chloride.

Chlorhexidine

CHX is a broad-spectrum agent used in therapeutic mouthrinses. CHX is both bactericidal and bacteriostatic with a duration of action of 8 to 12 hours in the oral cavity.⁵

Strong evidence shows that mouthrinses containing CHX effectively reduce biofilm. In combination with mechanical biofilm removal, the use of CHX in short or longer intervals up to 6 months shows a significant reduction in biofilm accumulation.⁶ The antimicrobial properties of CHX mouthrinse also help to reduce the bacterial load of biofilm, which may reduce inflammation. This action can help prevent primary and secondary biofilm-associated periodontal diseases. Evidence also suggests CHX leads to a moderate reduction in gingivitis among individuals with mild clinical symptoms.⁶ More studies are needed to differentiate the gingivitis reduction among patients with severe or moderate levels of biofilm.

Currently, CHX mouthrinses are available in concentrations of ≤ 0.06%, 0.1%, 0.12%, and 0.2% CHX digluconate.⁷ In the US, the most widely used concentration is 0.12%, which requires a prescription from a licensed professional.⁵ This recommendation is based on evidence showing that CHX is dose-dependent, with maximum effectiveness observed using either 10 mL of 0.2% CHX or 15 mL of 0.12% CHX, rinsed twice daily for 30 to 60 seconds.^7,8

Due to possible side effects, such as extrinsic staining, accumulation of calculus, altered taste, and burning sensation, dental professionals should monitor and educate patients on the established recommended use of CHX rinses.^5,6

Essential Oils

Essential oils (EO) have shown potential as both preventive and therapeutic agents for oral health, especially in dental care. Their wide-ranging antimicrobial and anti-inflammatory properties have made them great agents to help fight and kill various bacteria.^9,10 The term “essential” comes from their ability to capture a plant’s core taste and color. These water-soluble, plant-derived ingredients may offer healing and therapeutic benefits for various oral diseases.⁹

EOs target both Gram-positive and Gram-negative bacteria, including yeast, which cause many oral diseases.¹⁰ EOs frequently contain alcohols, esters, oxides, aldehydes, ketones, monoterpenes, diterpenes, and sesquiterpenes. All EOs are acquired from a plant source, such as bark, leaf, flower, fruit, or root; a large quantity of the source is required to make a small amount of EO.⁹

EOs obstruct bacteria from colonizing the tooth surface, inhibiting bacterial growth, preventing bacteria from clumping together with the initial layer of Gram-positive species, and removing toxins from Gram-negative pathogens. EOs damage the bacterial cell wall of the bacteria, inhibiting enzymes.¹⁰

Spearmint, lavender, cinnamon, coconut, and eucalyptus oils are among the most commonly used EOs in dentistry.¹¹ They are found in products such as toothpaste, mouthrinses, and gels.⁹ Most over-the-counter oral rinses combine three essential oils — thymol (0.063%), eucalyptol (0.091%), and menthol (0.042%) — to effectively target oral bacteria, reduce plaque, and support overall oral health.¹²

Other EOs, sometimes called herbal extracts, are used in mouthrinses, such as lemongrass, tea tree, eucalyptus, coconut oil, aloe vera, neem, curcumin, clove, and garlic. For example, tea tree oil and clove have demonstrated efficacy in reducing biofilms associated with gingival inflammation.^9,13

In a study combining tea tree, clove, and basil for an herbal mouthrinse, a decrease in plaque and gingival index scores over 21 days was observed with an overall reduction in both aerobic and anaerobic bacteria when compared to current commercially available EO mouthrinses.¹³

Some research shows that oil pulling with coconut and sesame oils is effective in reducing biofilm accumulation; however, more research is needed. A meta-analysis and a systematic review both concluded that while some benefits may exist, the time required, length of use, and formulation of the oils were inconsistent and some biases may be present in the published literature.^14,15 Until a strong evidence base is available, clinicians should use caution in recommending oil pulling.

EO mouthrinses have fewer side effects than other rinses, although some patients experience altered taste and burning sensation.^5,16 Patients who are sensitive to alcohol or those with a history of alcohol abuse should avoid EO mouthrinses that contain alcohol.⁵ Discussing alcohol and substance misuse is a sensitive topic for patients. A thorough review of the medical history and patient assessment using techniques, such as motivational interviewing during data collection, may assist a clinician in identifying a history of alcohol and drug misuse. Alcohol can be absorbed by a patient’s mucus membranes. The taste of alcohol may also pose an issue as it can trigger a desire that can lead to the risk of a relapse in a patient with a history of alcohol misuse.

Fluoride

Stannous fluoride and sodium fluoride are the most common fluorides used in mouthrinses. These active ingredients help treat demineralization, reduce hypersensitivity, and alleviate some gingivitis symptoms by disrupting cell metabolism and preventing further mineral loss.⁵

Fluorides can live within oral biofilms. With biofilm serving as a fluoride reservoir, mouthrinses containing fluoride should be able to access biofilm on the hard and soft tissue surfaces.⁵ For broader microbial action, fluorides are combined with additional ingredients. When incorporated into CHX solutions, sodium fluoride remained on the tooth structures and did not interfere with antimicrobial activity of the CHX.¹⁷ Similarly, the mixture of fluoride and cetylpyridinium chloride (CPC) is effective in biofilm reduction and caries prevention.¹⁸ This combination presents a viable option for individuals at risk for both dental caries and periodontal diseases.¹⁷

Amine fluoride disrupts biofilm and also shows efficacy when used in conjunction with other active ingredients. Amine fluoride can remain adhered to the surface of the teeth and oral tissues while withstanding disruption from saliva.¹⁹ In a randomized, triple-blind study testing the effectiveness of a mouthrinse containing both amine fluoride and CPC, a significant reduction in supragingival biofilm and in gingival index scores were observed.¹⁹ This is consistent with previous studies.

A randomized crossover study comparing three rinse formulations — CHX, amine/​stannous fluoride, and alcohol-free EOs —found that CHX and amine/​stannous fluoride demonstrated stronger antimicrobial effects than the alcohol-free EO rinse.²⁰ However, the study looked at short-term regrowth of bacteria; additional research is needed to assess longer intervals of biofilm regrowth.

Fluoride in combination with active ingredients in rinse, even used once per day for those at risk for both periodontal diseases and dental caries, may provide better prevention in conjunction with mechanical biofilm removal for periodontal diseases and dental caries.²¹

The most common side effects associated with fluoride mouthrinse include altered taste and extrinsic tooth staining.⁵ Oral ulcerations and paresthesia are also possible.²²

Cetylpyridinium Chloride

CPC, a quaternary ammonium compound, is able to disrupt biofilm formation due to its strong initial adherence to oral tissues. This helps prevent initial biofilm attachment to the acquired pellicle.⁵

Mouthrinses containing CPC disrupt the maturation of biofilm on surfaces, helping to delay the onset of gingivitis.²³ CPC is effective against supragingival biofilm. Its mechanism of action above the gingival margin interferes with the cell-to-cell communication necessary for building mature biofilms that cause gingival inflammation and gingivitis.²³

CPC is available in concentrations ranging from 0.045% to 0.10% for gingivitis. Formulations of 0.05% or more often yield the most significant results in preventing supragingival biofilm and reducing gingivitis.¹⁶ In a study comparing toothbrushing alone to the use of a CPC rinse and toothbrushing, the use of the rinse with the toothbrushing led to a reduction in both biofilm and gingival inflammation.²⁴ When compared to CHX and EO rinses, CPC rinses provide lower, but still statistically significant results on biofilm formation.²⁵ The severity of gingival inflammation and the location of biofilm should then be considered when recommending CPC as an adjunct oral hygiene aid.

CPC’s side effects are similar, but less severe than CHX. Research shows that irritation, taste alteration, staining and burning of oral mucosa are among the most commonly seen.^16,25

Conclusion

The incorporation of mouthrinses into a patient’s daily oral hygiene routine may help reduce biofilm formation and improve patients’ overall dental health. Evidence-based recommendations as well as the patient’s specific dental needs must be considered when choosing a mouthrinse.

References

1. Eke PI, Thornton-Evans GO, Wei L, et al. Periodontitis in US adults: National Health and Nutrition Examination Survey 2009-20J . J Am Dent Assoc. 2018;149:576-588.
2. Aas JA, Paster BJ, Stokes LN, et al. Defining the normal bacterial flora of the oral cavity. J Clin Microbiol. 2005;43:5721-5732.
3. Larsen T, Fiehn NE. Dental biofilm infections – an update. APMIS. 2017; 125: 376–384.
4. Rams TE, Sautter JD, Shin SS. Molecular iodine mouthrinse antimicrobial activity against periodontopathic bacteria. J Contemp Dent Pract. 2022;23:1183-1189.
5. Wilkins EM, Wyche CJ, Boyd LD. Wilkins’ Clinical Practice of the Dental Hygienist. 14th ed. Burlington, Massachusetts: Jones and Bartlett Learning; 2020.
6. James P, Worthington HV, Parnell C, et al. Chlorhexidine mouthrinse as an adjunctive treatment for gingival health. Cochrane Database Syst Rev. 2017;3:CD008676.
7. Keijser JA, Verkade H, Timmerman MF, Van der Weijden FA. Comparison of 2 commercially available chlorhexidine mouthrinses. J Periodontol. 2003;74:214-218.
8. Eley BM. Antibacterial agents in the control of supragingival plaque — a review. Br Dent J. 1999;186:286-296.
9. Singh I, Kaur P, Kaushal U, Kaur V, Shkhar N. Essential oils in treatment and management of dental diseases. Biointerface Research in Applied Chemistry. 2022;12(6):7267-7286.
10. Teles RP, Teles FR. Antimicrobial agents used in the control of periodontal biofilms: effective adjuncts to mechanical plaque control? Braz Oral Res. 2009;23 Suppl 1:39-48.
11. Haas AN, Wagner TP, Muniz FWMG, Fiorini T, Cavagni J, Celeste RK. Essential oils-containing mouthwashes for gingivitis and plaque: Meta-analyses and meta-regression. J Dent. 2016;55:7-15.
12. Van Leeuwen MP, Slot DE, Van der Weijden GA. Essential oils compared to chlorhexidine with respect to plaque and parameters of gingival inflammation: a systematic review. J Periodontol. 2011;82:174-194.
13. Kothiwale SV, Patwardhan V, Gandhi M, Sohoni R, Kumar A. A comparative study of antiplaque and antigingivitis effects of herbal mouthrinse containing tea tree oil, clove, and basil with commercially available essential oil mouthrinse. J Indian Soc Periodontol. 2014;18:316-320.
14. Peng TR, Cheng HY, Wu TW, Ng BK. Effectiveness of oil pulling for improving oral health: a meta-analysis. Healthcare (Basel). 2022;10:1991.
15. Woolley J, Gibbons T, Patel K, Sacco R. The effect of oil pulling with coconut oil to improve dental hygiene and oral health: a systematic review. Heliyon. 2020;6:e04789.
16. Leu-Wai-See P, Louis D. The power of mouthrinses. Dimensions of Dental Hygiene. 2023;21(10):16-18.
17. Villa O, Ramberg P, Fukui H, et al. Interaction between chlorhexidine and fluoride in a mouthrinse solution-a 4-day and 6-week randomized clinical pilot study. Clin Oral Investig. 2018;22:1439-1448.
18. Latimer J, Munday JL, Buzza KM, et al. Antibacterial and anti-biofilm activity of mouthrinses containing cetylpyridinium chloride and sodium fluoride. BMC Microbiol. 2015;15:169.
19. Priya BM, Galgali SR. Comparison of amine fluoride and chlorhexidine mouth rinses in the control of plaque and gingivitis — a randomized controlled clinical trial. Indian J Dent Res. 2015;26:57-62.
20. Marchetti E, Casalena F, Capestro A, Tecco S, Mattei A, Marzo G. Efficacy of two mouthwashes on 3-day supragingival plaque regrowth: a randomized crossover clinical trial. Int J Dent Hyg. 2017;15:73-80.
21. Marsh L, Cahoon M. Improve oral health through mouthrinse use. Dimensions of Dental Hygiene. 2018;16:14-18.
22. Tartaglia GM, Tadakamadla SK, Connelly ST, et al. Adverse events associated with home use of mouthrinses: a systematic review. Ther Adv Drug Saf. 2019;10:2042098619854881.
23. Teng F, He T, Huang S, et al. Cetylpyridinium chloride mouth rinses alleviate experimental gingivitis by inhibiting dental plaque maturation. Int J Oral Sci. 2016;8:182-190.
24. Langa GPJ, Muniz FWMG, Costa RDSA, da Silveira TM, Rösing CK. The effect of cetylpyridinium chloride mouthrinse as adjunct to toothbrushing compared to placebo on interproximal plaque and gingival inflammation-a systematic review with meta-analyses. Clin Oral Investig. 2021;25:745-757.
25. Takenaka S, Sotozono M, Ohkura N, Noiri Y. Evidence on the use of mouthwash for the control of supragingival biofilm and its potential adverse effects. Antibiotics (Basel). 2022;11:727.

From Dimensions of Dental Hygiene. May/June 2025; 23(3):40-45.