Efficacy of Therapeutic Mouthrinses

Therapeutic mouthrinses are a key part of the dental hygienist’s product arsenal to help patients achieve and maintain oral health. Both cosmetic and therapeutic mouthrinses are popular with patients because they are quick and simple to use. Cosmetic mouthrinses are designed only to reduce malodor; they do not address the causes of malodor. Therapeutic mouthrinses include ingredients, such as antimicrobial agents and fluoride, that contribute to caries reduction and the treatment of gingivitis and dentinal hypersensitivity.^1-3

ANTIGINGIVITIS MOUTHRINSE AGENTS

Gingival inflammation causes poor oral health and is a precursor to chronic periodontitis. The presence of plaque biofilm above and below the gingival margin causes gingivitis. The cyclic nature of bacteria survival and metabolism must be interrupted regularly to reduce inflammation levels and bleeding sites in patients with gingivitis. Unfortunately, many people do not floss daily, giving plaque bacteria the ability to grow stronger and become more resistant to removal.¹ Patients may have behavioral or physical limitations that affect their ability to effectively remove plaque.

Patients with these types of limitations or those who need additional help with plaque management are good candidates for therapeutic mouthrinses. A variety of ingredients is used in therapeutic mouthrinses to address gingivitis but the American Dental Association only recognizes chlorhexidine and essential oils as effective agents against plaque and gingivitis. Chlorhexidine, a chemical antiseptic, is the gold standard in chemical plaque control. Chlorhexidine mouthrinses can target a wide variety of microorganisms by damaging the bacterial cell wall, absorbing onto hard and soft tissue surfaces for sustained effects, and inhibiting bacterial colonization.⁴ It can also permeate tissues on a cellular level, allowing elevated and extended substantivity. In addition, chlorhexidine has antiplaque and anti-inflammatory capabilities, which reverse the clinical signs of inflammation caused by gram-positive and gram-negative bacteria.⁵ Chlorhexidine is available in both a nonalcohol and an alcohol-containing formulation.

Research shows that chlorhexidine mouthrinse reduces plaque levels by 50.3% to 60.9% and reduce gingivitis by 30.5% to 42.5%.¹ Side effects include generalized staining, altered taste, mucosal ulceration, increased supragingival calculus formation, and swelling in the parotid papilla.⁵ Chlorhexidine mouthrinse is available only by prescription. Essential oils-thymol, menthol, eucalyptol, and methyl salicylate-are the most common ingredients in therapeutic mouthrinses designed to control gingivitis. They are antibacterial in nature, inhibiting the formation of plaque and bacterial microbes that cause gingivitis. Research shows that the use of essential oils in a mouthrinse is effective in reducing plaque by 13.8% to 56.1% and in reducing gingivitis by 22.1% to 35.9%.¹

Quaternary ammonium compounds, such as cetylpyridinium chloride (CPC), benzethonium chloride, and domiphen bromide, may also help reduce plaque. Quaternary ammonium compound mouthrinses typically contain concentrations of 0.025% to 0.075%. Research demonstrates that these compounds offer moderate plaque reduction when used in mouthrinses.⁶ Oral ulceration, burning sensation on the tongue, and bitter taste are reported side effects. Some naturally-occurring ingredients are also effective in treating gingivitis by helping reduce gingival bleeding.⁷ A study by Haffajee et al found that herbal mouthrinses containing aloe vera, calendula (anti-inflammatory agent), and goldenseal and grapefruit seed (antimicrobial agents) effectively inhibited the growth of periodontal pathogens Eubacterium nodatum, Prevotella intermedia, Prevotella melaniogenica, Prevotella nigresecens, and Tannerella forsythia and the caries pathogen Streptococcus mutans.⁷ However, the same study found that herbal mouthrinses were not as effective as those containing chlorhexidine gluconate in treating gingivitis.

Peroxide-based mouthrinses have been used in dentistry for more than 70 years. They create an aerobic atmosphere, destroying disease-inducing microorganisms.⁸ A study by Hoenderdos et al looked at the efficacy of a peroxide and glycerol mouthrinse on plaque accumulation. The hypothesis was that the peroxide and glycerol combination would create a sustained aerobic environment. Glycerin increases the stability of the hydrogen peroxide, which creates a longer contact time and improves the antiplaque effects.⁸ However, no difference was found when comparing the results of the peroxide/glycerol mouthrinse to diluted glycerol only. Another study found that a 0.05% sodium fluoridated and 1.5% hydrogen peroxide-based mouthrinse was effective in reducing stain, bleeding sites, and gingivitis.⁹ Peroxide-based mouthrinses are typically used for a brief period and in diluted concentrations. Chlorine dioxide is used in commercial dairy, beverage, and food industries and as an oxidant in water treatment. It is a highly effective, nontoxic broad spectrum microbiocide with demonstrated efficacy over a wide pH range. Chlorine dioxide was first used in dentistry as an oxidizing biocide compound to treat malodor.

Chlorine dioxide causes fewer side effects than chlorhexidine so its effectiveness in treating gingivitis is currently being studied. In a study comparing the efficacy of a chlorine dioxide mouthrinse and a chlorhexidine mouthrinse in reducing plaque, chlorhexidine was found to be more effective in preventing plaque accumulation. 10 However, patients preferred the taste of the chlorine dioxide rinse and they experienced less taste alteration after its use.¹⁰ Further research is needed to investigate the effect of a chlorine dioxide mouthrinse in the treatment of gingivitis and periodontal disease.

CARIES PREVENTION

Approximately 23% of children, adolescents, and adults in the United States have untreated dental caries while 92% of adults between the age 20 and age 64 have had caries in their permanent teeth.¹¹ Reducing the prevalence and severity of caries is an important step toward improving oral health in the United States. Lactobacillus acidophilus and Streptococcus mutans are the main bacteria involved in the caries process. Mouthrinses with antibacterial and anticariogenic properties are effective in remineralization and in the prevention of incipient and new lesions.

Fluoride is the gold standard in caries prevention. Research shows that the long-term use of sodium fluoride in children reduces bacterial levels of S. mutans and S. sobrinus in saliva.^11-13 Daily exposure to low concentrations of 0.05% sodium fluoride in mouthrinses is effective in promoting remineralization and preventing incipient caries.¹² Kaneko et al demonstrated that the weekly use of a 0.2% sodium fluoride mouthrinse reduced caries by 47% in children.¹³

Research focused on the use of fluoride mouthrinses for interproximal incipient caries demonstrated that a combined sodium (150 ppm) and amine (100 ppm) fluoride rinse resulted in increased fluoride uptake and remineralization of interproximal areas.¹⁴ Vogel et al demonstrated that an over-the-counter sodium fluoride mouthrinse in individuals with heavy interproximal plaque resulted in low plaque fluoride uptake.¹⁵ This study infers that heavy plaque should be removed prior to using a fluoride mouthrinse.

Chlorhexidine is also useful in preventing caries because of its ability to reduce S. mutans levels.¹⁶ In a comparison of S. mutans levels after rinsing with 0.12% chlorhexidine, 0.05% sodium fluoride, and 0.3% triclosan, chlorhexidine reduced most of the S. mutans but did not promote remineralization.¹⁷ Sodium fluoride and triclosan had better remineralization qualities. This may be due to the fact that chlorhexidine’s remineralization abilities decrease over time while sodium fluoride’s ability to remineralize increases over time.¹⁷ Patients interested in a holistic approach may look for natural ingredients that offer similar health benefits to those provided by artificial ingredients.

The Food and Drug Administration does not have a clear definition for what is considered “natural,” but typically this is an indication that the product is free of synthetic colors, preservatives, flavors, sweeteners, and stabilizers. A mouthrinse containing 0.05% sodium fluoride as well as water, vegetable glycerin, aloe, sodium phosphate monobasic, xylitol, olivamidopropyl betaine, menthol, and grapeseed extract showed similar results to other 0.05% sodium fluoride rinses in reducing bacteria and fluoride uptake.¹⁸ On the other hand, a calcium fluoride 200 ppm, over-the-counter natural anticaries mouthrinse was found to be less able to remineralize incipient caries when compared to similar concentrations of pharmaceutical rinses.¹⁹ Additional studies are necessary to compare the effectiveness of natural fluoride rinses in reducing carious lesions. Overall, fluoride mouthrinses are an effective addition to the prevention armamentarium and should be recommended to reduce caries.

DENTINAL HYPERSENSITIVITY

Dentinal hypersensitivity is a common cause of oral pain.²⁰ The intermittent pain caused by thermal, tactile, chemical, evaporative, or osmotic stimuli occurs when dentinal tubules are exposed. Treatment consists of blocking the dentinal tubules or transforming the sensory activity of the pulp. Stannous fluoride mouthrinses are used to occlude dentinal tubules, while rinses containing potassium nitrate work to inactivate the nerves. In a research study, a 3% potassium nitrate/ .02% sodium fluoride mouth rinse provided more relief in overall sensitivity and cold air tests when compared to a 0.2% sodium fluoride mouth rinse.²¹ The consistent use of mouth rinses to alleviate sensitivity typically provides the best results.²²

Erosion causes painful tooth sensitivity, which results in oral hard tissue loss. The use of stannous fluoride can prevent the loss of oral hard tissues.^23,24 A 0.2% concentration of stannous fluoride has antimicrobial properties and reduces oral acidity levels by 80%.²⁴ Research performed in vitro shows that higher concentrations of stannous fluoride reduced tooth erosion by 60% to 90% in tooth specimens treated with citric acid, representing demineralization.²⁴ Stannous fluoride concentrations show an increased protective ability against enamel erosion when compared to sodium fluoride due to their increased ability to create a calcium fluoride barrier and the tin ion’s ability to coat enamel.²⁵ In this study, tooth specimens were pretreated with human saliva and subjected to hydrochloric acid to represent an acid attack similar to that caused by acidic beverages.

Interestingly, this research also concluded that enamel erosion was completely prevented when stannous fluoride was used immediately following an acid attack.²⁵ Yu et al found that a stannous chloride-containing fluoride rinse prevented enamel loss under acidic conditions in vitro. Tooth specimens were covered in saliva so they formed salivary pellicle and then were exposed to acid repeatedly.²⁶

Mouthrinses offer therapeutic benefits in treating gingivitis, reducing caries, and alleviating pain. While various types of therapeutic mouthrinses are available, oral health care providers need to stay up to date on the latest research in order to provide their patients with evidence-based recommendations. When recommending over-the-counter therapeutic mouthrinses, the American Dental Association (ADA) Seal of Acceptance is an indication of proven efficacy.

REFERENCES

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From Dimensions of Dental Hygiene. November 2010; 8(11): 46-49.