What you need to know about oral rinses

For a variety of reasons (including lack of motivation, dexterity and/or resources) many patients struggle with maintaining proper mechanical plaque removal regimens.

Additionally, mechanical plaque removal does not eliminate the plaque biofilm, which remains on the soft tissues (the lips, buccal mucosa, attached/free gingiva, the tongue, the floor of the mouth, etc.), which comprise approximately 80 percent of the oral cavity. To remedy these shortcomings, the American Dental Association (ADA) recommends that oral rinses be incorporated into daily oral hygiene practices.

Oral rinses are used for cosmetic purposes to freshen breath or to whiten teeth, and therapeutic purposes to help prevent or control tooth decay and gingivitis, and to reduce plaque biofilm.

Microbiology

A bacterium is protected from its environment by a membrane on the bacterial wall, the integrity of which is essential to survival of the bacterium. This membrane consists of basic compounds such as phospholipids and lipopolysaccharides. The bacterial wall is important, as this confers rigidity and differs considerably between gram-positive and gram-negative bacteria. This diversity leads to great variation in the potency of antimicrobial agents.  

Phenols

Plants contain fragrant components that protect the plant in continually changing internal and external environments. The International Organization for Standardization defines an essential oil (EO) as a product made by distillation of these components with either water or steam.¹ EOs are antibacterial, antiviral, antifungal and antimicrobial, hence their efficacy in combating oral pathogens. They are also known to have anti-inflammatory and anti-oxidative (oxidation is the loss of at least one electron when two or more substances interact; this causes damage to the cell) properties², and few side effects which add to their ease of use. EOs also possess high specificity (effective against many different bacteria), but low substantivity (duration of antimicrobial action). The active ingredients in Listerine are a combination of three EOs: thymol 0.063%, eucalyptol 0.091%, and menthol 0.042%, along with other ingredients (i.e., methyl salicylate 0.0660%).³

Bis-biguanides

These are a class of chemical compounds, including chlorhexidine, with strong antibacterial properties. The mechanism of action is to bind strongly to bacterial cell membranes, increasing the cell permeability, thus initiating leakage of intracellular components. Furthermore, bis-biguaides reduce pellicle formation and hinder the adsorption of bacteria onto the tooth structure. Chlorhexidine is a broad-spectrum agent effective against gram-positive and gram-negative bacteria, fungi, yeasts and some viruses. It has high substantivity, over seven to 12 hours after rinsing. It is considered the gold standard, the most potent of all chemotherapeutic agents. Disadvantages include brown staining of the teeth, tongue and restorations, alteration of taste perceptions, strong, bitter taste and increased calculus formation. There is some discrepancy regarding using a dentifrice containing sodium lauryl sulfate with some researchers finding no difference in efficacy when combining the two and others finding that SLS reduced the antimicrobial action of CHX. Without a clear distinction, the recommended procedure has been to use the SLS-containing dentifrice at least 30 minutes and preferably two hours after CHX rinsing.

Quaternary ammonium compounds

Quaternary ammonium compounds (QACs) irreversibly bind to the phospholipids and proteins of the membrane, thereby impairing permeability. The capacity of the bacterial cell to absorb such molecules influences sensitivity; the agent becomes bound to the wall proteins and is thus able to enter and destroy the membrane. Cetylpyridinium chloride is an example of a QAC and is found in Crest Pro-Health. CPC shares some of the adverse effects of CHX, including tooth staining, burning and increased calculus formation and does not have high substantivity.

Herbal extracts

Asian countries have used traditional herbal medicines to treat infectious diseases for thousands of years. Many herbal extracts have proven to be powerful antimicrobials including pomegranate, Acacia nilotica, clove, Cinnamum zeylanicum, acacia, Araucaria bidwilli Hook, rosemary, evergreen, Sappan Lignum, S. flavescens, garlic, turmeric, and Psoraleae Semen.^{4,5,6,7, 8}  Sanguinaria canadensis (bloodroot) has particularly high substantivity and its effectiveness as an antimicrobial has been well studied and documented.⁹ Studies have shown that usage of herbal mouthwashes compared to chlorhexidine resulted in a significant reduction in plaque indices scores, gingival indices scores and gingival bleeding index scores.

Chlorhexidine was found to be more effective on aerobic and anaerobic micro-organisms. Well documented side effects of chlorhexidine like tooth staining, taste alteration, and development of resistant microorganisms limits its use, especially in children. Therefore, oral rinses which incorporate herbal extracts can serve as an alternative in patients with special health care needs. The problem with these herbal rinses is that they are not regulated by the Food and Drug Administration (other oral rinses such as Listerine, Pro-Health and Peridex are approved by the FDA) so one cannot be sure of the percentage of the extract that is actually in the rinse.

Bleach

Boasting a 100-year safety record, sodium hypochlorite (common household bleach) is one of the most potent antiseptic and disinfectants available, effectively killing bacteria, fungi and viruses. Because it is present naturally (in neutrophils, monocytes and macrophages) is causes no allergic reactions and is not a teratogen or a carcinogen. It also doesn’t produce any side effects such as staining, does not cause irritation to mucosal tissues, does not erode tooth structures or titanium implants.¹⁰ The American Dental Association Council on Dental Therapeutics has long supported sodium hypochlorite as an antiseptic mouthrinse.¹¹ Patients should be instructed to rinse with two tsps of 6% household bleach diluted in one cup of water for 30 seconds two to three times per week.¹⁰

Salt water rinse

The antiseptic action of salt on the skin and mucous membranes has been documented for over 2500 years. Egyptians used salt to make laxatives and anti-infectives, Hippocrates created a mixture of salt and honey to clean bad ulcers, and was the first to discover the antiinflammatory effects of inhaling steam from salt-water. The antiseptic and bactericidal qualities of dental salt (sea salt) come from its ability to increase the pH balance of saliva, creating an alkaline environment which make survival difficult for pathogenic bacteria. Add half a teaspoon-to one teaspoon of salt to a cup of warm water and rinse for approximately 20 seconds a couple of times a day.

Triclosan

Triclosan, a bis-phenyl, is a very effective, broad-spectrum antimicrobial agent. Its judicious use in hospital settings by trained healthcare providers is undisputed. However, it has been implicated in a variety of harmful health effects including endocrine disruption, impaired muscle contraction, developmental and reproductive toxicity and carcinogenesis.^12,13

Environmental effects on aquatic ecosystems include severely limiting microbial diversity which leads to adverse effects in species higher up the food chain, not to mention the potential numbers of microorganisms who become resistant to the drug (contributing to the serious problem of antibiotic resistance). It is available in the product Colgate Total Plax. Interesting to note that Colgate-Palmolive removed triclosan from its soap products yet still utilizes it for its toothpaste, Colgate Total Care.¹⁴

Halogens/fluoride

Stannous fluoride has anticariogenic and antibacterial properties. The use of stannous fluoride as an antibacterial is limited due to its instability and side effects. Amine fluoride stabilizes stannous fluoride and formulations including the two have been shown to be comparable to CHX in reducing oral bacterial accumulations. The negative effects of stannous fluoride include staining and a bitter, metallic taste. Iodine and its derivatives are the broadest spectrum and potent antiseptics available, and are also able to kill the Herpes virus. There are few negative side effects, it has low financial cost, does not encourage bacterial resistance and any stains it produces can be easily removed. Those allergic to iodine, pregnant/nursing women and those with thyroid dysfunction should not use it. A 10% PVP-iodine solution was shown to be a useful irrigant following periodontal debridement and root planing with great success: Five weeks after nonsurgical periodontal therapy (including root planing) 44 percent of treated sites revealed pathogen reduction of 95 percent or more.¹⁵

Oxygenating agents

Gram negative bacteria are highly sensitive to active oxygen. Hydrogen peroxide breaks down into water and oxygen and effectively kills bacteria. Oxygenating agents such a hydrogen peroxide have been used for many years to disinfect oral tissues. Researchers tested Ardox-X, formulated with peroxyborate and specific carriers such as glycerol and cellulose, and reported a significant microbial shift in composition of oral bacterial species such as Streptococcus and Veillonella. These agents also produce the added benefit of bleaching on teeth. Peroxide, however, is unstable and difficult to store thus limiting its use. Long-term studies have shown a lack of adverse effects to the soft tissues of the mouth in when used in low concentrations (<2%)¹⁶.In high concentrations (>30% solution) soft tissues may exhibit erythema or mucosal sloughing, inflammation or hyperplasia.¹⁷

Sources

1. International Organization for Standardization. http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?cs number=51017
2. Adorjan, Barbara, and Gerhard Buchbauer. "Biological properties of essential oils: an updated review." Flavour and Fragrance Journal; 25.6 (2010)
3. Asadoorian, J. “CDHA Position Paper on Commercially Available Over-the-Counter Oral Rinsing Products”. Canadian Journal of Dental Hygiene; 40.4 (2006)
4. Yim et al. “Screening of aqueous extracts of medicinal herbs for antimicrobial activity against oral bacteria”. Integrative Medicine Research; 2.1 (2013)
5. Lee, S. “Antimicrobial effects of herbal extracts on Streptococcus mutans and normal oral streptococci”. Journal of Microbiology; 51.4 (2013)
6. Salam et al. “Antimicrobial activity of medicinal plant for oral health and hygiene”. International Journal of Natural and Social Sciences; 2.1 (2015)
7. Mali et al. “Comparative evaluation of 0.1% turmeric mouthwash with 0.2% chlorhexidine gluconate in prevention of plaque and gingivitis: A clinical and microbiological study”. Journal of Indian Society of Periodontology; 16.3 (2012)
8. Dabholkar, C. S., Shah, M., Kathariya, R., Bajaj, M., & Doshi, Y. (2016). Comparative Evaluation of Antimicrobial Activity of Pomegranate-Containing Mouthwash Against Oral-Biofilm Forming Organisms: An Invitro Microbial Study. Journal of Clinical and Diagnostic Research: JCDR, 10(3), ZC65.
9. Eley, B. “Antibacterial agents in the control of supragingival plaque - a review”. British Dental Journal; 186.6 (1999)
10. Slots, Jørgen. "Low-cost periodontal therapy." Periodontology 2000 60.1 (2012): 110-137.
11. American Dental Association. “Accepted dental therapeutics”. Chicago IL: American Dental Association, 1984, p. 326
12. Yueh et al. “The commonly used antimicrobial additive triclosan is a liver tumor promoter”. Proceedings of the National Academies of Sciences; 111.48 (2014)
13. Halden, R. “On the Need and Speed of Regulating Triclosan and Triclocarban in the United States”. Environmental Science and Technology; 48 (2014).
14. Business Insider. Colgate-Palmolive removed this potentially harmful chemical from its soap products -but it’s still in your toothpaste. http://www.businessinsider.com/triclosan-cancer-causing-ingredient-in-colgate-toothpaste-2014-8
15. Hang et al. Povidone-iodine as a periodontal pocket disinfectant. Journal of Periodontal Research; 38 (2003)
16. Mostajo et al. “Effect of an oxygenating agent on oral bacteria in vitro and on dental plaque composition in healthy young adults”. Frontiers in Cellular and Infection Microbiology; (2014)
17. Walsh, L. “Safety issues relating to the use of hydrogen peroxide in dentistry”. Australian Dental Journal; 45.4 (2000)