The 80-20 rule, or Pareto principle,1 is the idea that a relatively small percentage of any cause (20%) creates most of the subsequent effects (80%). In a business context, this means that 80% of a company’s business stems from 20% of its customers.
In dentistry, teeth make up only 20% of the surface area of the mouth, with the other 80% including interproximal spaces, the dorsum of the tongue and cheeks, and below the gumline; all reservoirs and niches for biofilm.2 There is a similar 80-20 situation happening with biofilm: 20% are pathogens and 80% is a slime layer composed of self-secreted glycoproteins and polysaccharides that is difficult to penetrate.3 Brushing and interproximal cleaning alone is not enough to disrupt biofilm. Often in practice, periodontal disease is synonymous with periodontitis. This is incorrect. Periodontal disease is a continuum, a type of wound. Mealey and Rose4 discuss the periodontium as a unique ecological niche in the human body. Prior to the eruption of teeth, the tissue is intact, yet inhabited by bacterial communities that don’t challenge the individual’s health, similar to the bacteria that thrive harmlessly on your skin. When the teeth erupt, this surface can have as many as 32 objects violating this formerly intact mucosa.4 This creates the potential for biofilm and promoters of inflammation to reach the bloodstream.
Often in practice, the words "biofilm" and "plaque" are used interchangeably. This too can be incorrect, or at least confusing. When talking about home care, we need to consider the makeup and location of biofilm, not plaque. Many of us completed our education at a time when bacteria were studied in a free-floating planktonic state. This led to the concept that certain pathologic pathogens were the reason for the breakdown. Dental professionals once thought that the thorough removal of supra- and subgingival plaque and deposits, and proper home care, would promote health. It is now known that biofilms are medically/dentally important. We also know that microbes living in a planktonic state that are nonadherent and free-floating cause few diseases. An oral biofilm environment is an accumulation of a mixed population of bacteria, fungi, or protozoa that produce large amounts of slime or matrix material around themselves.4 Using the terms "biofilm" and "plaque" interchangeably can confuse our understanding.
Because of the work of Costerton,3 we know that biofilm is a complex community and it has a tremendous ability for self-preservation.3 Yet biofilm is not inherently bad. Biofilms are common in nature, yet damage can occur. Biofilm moving from a healthy to disease-inducing state can be prevented by routine home care. It is the routine disruption that keeps the biofilm in a healthy state.
With this understanding of the 80-20 of biofilm, let’s look again at the 80-20 of common oral home care. Emphasizing brushing and interproximal cleaning to disrupt the biofilm is not enough. mouthrinse must be added to penetrate the 80% slime layer adhering to 80% of the oral cavity.
Using Evidence-Based Dentistry in Product Selection
How can professionals make a recommendation to Ashley? The answer lies in evidence-based dentistry (EBD). EBD is research. Clinical recommendations have 3 parts: (1) the evidence, (2) our professional experience and judgment, and (3) the patient’s clinical/social circumstances and preferences (Figure).5 Clinical recommendations are the overlap of these 3 areas.
In the 21st century, EBD can now be accessed easily via the Internet. Computers have become ubiquitous; most households have at least one or more of them. The reason for this is that we can do/learn/create differently with them. Using computers in healthcare, including the soon-to-be interoperable electronic health records, doesn’t just take what we have done traditionally and make it electronic. Rather, the use of computers opens options we didn’t have before, including finding research as part of the EBD process. The ADA has developed a website dedicated to EBD at ebd.ada.org.
Although EBD is not a linear process, we will break down our journey into steps. EBD requires the judicious integration of systematic assessments of clinically relevant scientific evidence. We will begin step one in our EBD journey of mouthrinses by looking at 5 antimicrobial active ingredients in many of the over-the-counter (OTC)/prescription mouthrinse options.
Evidence-Based Dentistry, Step 1—Science of the Options
There are 5 main antimicrobial active ingredients in mouthrinses on the market today (Table).
Essential oils have been around for thousands of years. They were first added to LISTERINE in 1879, but used as an antiseptic, not a mouthwash. In 1895, dentists started using it. In 1914, it became the first OTC mouthwash. LISTERINE is probably the most researched mouthwash on the market. The 4 essential oils used in the mouthwash are thymol, menthol, eucalyptol, and methyl salicylate. The oils disrupt the bacterial cell wall and kill biofilm and gingivitis organisms rapidly and nonselectively. Essential oils exhibit a broad spectrum of activity against Gram-positive and -negative bacteria, as well as fungi.
As a result of reducing the number of pathogenic bacteria in the mouth, biofilm endotoxin levels are also reduced. This in turn decreases the pathogenicity of biofilm and the development of gingivitis.6,7 Essential oil rinses are available in both alcohol-containing and alcohol-free versions; however, the alcohol-free products might not meet the same efficacy standards. The alcohol in therapeutic mouthrinses contains pharmaceutical-grade denatured alcohol to solubilize all the ingredients.
As with essential oils, chlorhexidine (CHX) also ruptures the bacterial cell membrane, leading to rapid leakage of cell contents and cell death. Unlike essential oils, CHX binds salivary mucins, which reduces pellicle formation and in turn inhibits biofilm bacteria colonization. CHX also binds bacteria, further inhibiting their absorption onto tooth surfaces. CHX exhibits a broad spectrum of antimicrobial activity and is effective against both Gram-positive and -negative bacteria.8-9 CHX is available with and without alcohol. Due to its substantivity, CHX is often called the gold standard to which other rinses are compared.
Cetylpyridinium chloride (CPC) is similar to CHX in that it too ruptures the bacterial cell membrane, leading to rapid leakage of cell contents and cell death. CPC may also alter bacterial metabolism and inhibit cell growth. CPC was first discussed in the scientific literature in the late 1930s and is included in many popular mouthrinses with varying concentrations, the most popular being Crest Pro-Health. It is important to recognize that the minimum recognized therapeutic concentration for CPC is 0.045%. Many cosmetic mouthrinses contain CPC at concentrations below 0.045%, and do not provide antiplaque/antigingivitis benefits. There are both alcohol-containing and alcohol-free products on the market.10,11
Stabilized chlorine dioxide (CloSYS, Oxifresh) has been around for almost 200 years, but there are insufficient studies showing clinical efficacy against gingivitis. It also does not have the ADA seal. Manufacturers claim the products oxidize, causing chemicals to unite with oxygen and kill bacteria that cannot survive in an oxygenated environment. There is a body of literature to show that chlorine dioxide reduces oral malodor. One in vitro study shows the potential for microbial kill. This study states that it is "an attractive option to induce compliance in patients concerned with taste and discoloration."
The advantage of using rinses with chlorine dioxide is that they do not contain alcohol, they do not cause staining, they are pH-balanced, and can be used with or without flavorings. They do not require a prescription. However, more long-term research needs to be done.12,13
There is a new ingredient on the US market that shows great promise: Delmopinol hydrochloride 0.2% in G·U·M PerioShield (Sunstar Americas) is a proprietary key ingredient that creates a less-adhesive environment for bacteria and biofilm. This rinse prevents bacteria from sticking to the teeth, forming an invisible protective shield over the teeth and gingiva that bacteria cannot penetrate, essentially reducing biofilm buildup. The product breaks down the biofilm and bacteria, making them easier to remove, while coating the teeth and gums to prevent additional biofilm from sticking. As a result, continual use helps maintain a healthy, balanced microflora. In other words, delmopinol does not directly kill anything. There is a small amount of alcohol (1.5%). It is less staining than CHX and has shown good results in clinical trials.14-17
The product has been available in Europe for at least 10 years, and just recently came to the US market. This rinse was studied in meta-analyses of 8 double-blind studies looking at it as an adjunct to gingival health and biofilm control measures. Delmopinol met the efficacy criteria of the ADA in studies of extended durations. According to the manufacturer, G·U·M PerioShield was developed for patients with chronic gum inflammation, gingivitis, and severe biofilm buildup. It has been proven safe and effective for long-term use. The product is currently the only oral rinse available approved by the FDA as a device (Class II medical device), whereas all other antibiofilm/antigingivitis rinses are classified as drugs. An FDA Class II medical device is defined as: "…intended to affect the structure or any function of the body of man or other animals, and which does not achieve any of its primary intended purposes through chemical action within or on the body of man or other animals and which is not dependent upon being metabolized for the achievement of any of its primary intended purposes."
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