By Adin Smith, MS
We are all aware that brushing our teeth, flossing and regular dental cleaning checkups helps prevent plaque build-up. However, oral polyphenolic mouthwashes may become recommended as an additional step to help prevent plaque, cavities and diseases of the gum. Over the last 15 years, research has shown that green tea, black tea and extract from cranberries may provide protection against the development of cavity formation and gum disease 1,2,3,4,5. Polyphenols contained in teas and certain berries may act to inhibit the production of teeth eroding acids and biofilms (a biofilm is a compartmentalized environment that causes bacteria and cells to act differently 6 ) caused by pathogenic bacteria. Some of the pathogenic bacteria in the mouth, such as streptococcus mutans, when abundant, may cause decreases in the pH of the biofilm (a pH of <5.5) resulting in tooth enamel erosion 7.
The oral cavity is similar to the gastrointestinal tract in that ratios of certain pathogenic bacteria, neutral, and healthy bacteria must be in balance. When biofilms build up on tooth surfaces the ecology of the bacteria is altered in a way that promotes the increase of disease promoting organisms, which can lead to cavity formation. Streptococcus mutans (s. mutans) produces glucosyltransferase that binds strongly to tooth surfaces, causing other microorganisms to then bind to its surface, resulting in dental plaque formation and enhancing the stability and structural integrity of the biofilm 8. Tooth physiology is unique in that no other surface in the human body is non-shedding. Thus, the tooth surfaces are more susceptible to damage from pathogenic changes in bacteria as tooth cells are unable to die and regenerate. Instead, pathogenic bacterial biofilms that adhere to tooth surfaces can wear away the tooth structures and cause permanent decay.
In a recent evaluation of three types of mouthwashes containing chlorhexidine (a prescription antibacterial agent), Listerine® (an over the counter mouthwash) and a tulsi extract (green tea), the tulsi extract was found to be as equally effective in reducing salivary S.mutans 9. In vitro and in vivo studies using cranberry proanthocyanidins extract treatments showed reduced formation of biofilms by S. mutans 4,10,11. It is important to note that chlorhexidine does stain the teeth, which often results in poor compliance in those that use it. However, professional tooth whitening procedures done by a dentist may be able to offset these side effects. Listerine (now recommended without alcohol) shows some clinical effectiveness without staining the teeth. It remains unknown if mouthwash extracts using green tea will cause staining, but it is well known that heavy consumers of green and black teas do experience tooth stain.
In a randomized trial completed just last month, a mouthwash containing 2% green tea was shown to be effective in reducing plaque and gingival index scores 1. Green tea extract mouthwash has also been effective in the reduction of biofilms on acrylic resins 12, which is important for those using dentures. A trial involving 157 school-children showed that chewing gum that contained tea polyphenols and xylitol (a sugar alcohol) were superior to standard gum in protection against caries 13. Chewing gum stimulates salivary flow which has a buffering effect on the plaque pH (saliva makes the mouth more alkaline, and, pathogenic-biofilms are acidic). An increase in salivary flow also helps clear the teeth of food debris and prevent the accumulation of microorganisms. The decayed-missing-filled index (DMF) has been used for more than 70 years to describe dental status and treatment need 14. This study on chewing gum showed that the xylitol and tea phenol group significantly lowered the DMFT and DMFS scores compared to the control group (regular gum) and the group with no chewing gum 13.
Mouthwashes, toothpastes, and perhaps even chewing gums, of the future may be able to provide protection against oral diseases as effectively as fluoride and may be preferable due to the potential toxicities of fluoride exposure. An example of fluoride over-exposure is in the accidental swallowing of sodium fluoride during tooth brushing by children. Cai, et al. audited 180 young children and found that the average amount of ingestion of fluoride from toothpastes resulted in excessive daily fluoride intake 15. Fluorosis results from excessive exposure and ingestion of fluoride, which can result in mottled teeth. A recent meta-analysis showed an inverse relationship between fluoride exposure and intelligence. Children who lived in areas of high fluoride exposure had lower IQ scores than in those who lived in low-exposure areas 16. It should be noted that the authors in this meta-analysis disclosed the obvious limitation, as this study pooled together observational types of studies and cannot draw a definitive cause and effect relationship. Evaluating fluoride exposure is extremely difficult, as misclassification of exposure groups can occur if children were drinking water from sources that contain different levels of fluoride, as an example.
The Center of Disease Control (CDC) notes that fluorosis only occurs in children ages eight or younger, during a time when teeth are still developing underneath the gums 17. Children under eight years of age should be carefully monitored by adults to prevent an overdose. Only a pea-sized amount is advised when applying toothpaste to a brush, as fluoride concentration is much higher in toothpaste than in tap water. Above all, parents need to make sure that the child does not swallow fluoridated toothpaste. Fluoridated tooth pastes are not to blame for fluorosis, but fluorosis can occur through improper usage of toothpaste.
For those who live in areas where the water supply is not fluoridated, it is necessary for children to apply a topical fluoride in the form of toothpaste. Professionally applied fluorides in the form of a gel, foam, or rinse are applied during regular dental hygiene visits and are especially important for children ages 2-8 years of age living in non-fluoridated areas .Well water should be tested for fluoride concentration to determine if fluoride needs to be added.
Even more important, systemic levels of fluoride (by fluoride ingestion) are needed from infant development through age 8. Optimal structure and function of the teeth are partially dependent on systemic fluoride levels. Fluoride gets shuttled into the teeth during the critical time of teeth formation and maturation by way of oral ingestion and topical applications. Children that do not receive adequate fluoride during the developing years will not achieve maximal tooth strength and resilience to cavities. Many parents use bottled water when preparing food, juices or water for infants and young children. Many bottled water sources do not contain adequate fluoride content to provide a protective effect in young children.
Watson, et al. showed that fluoride penetrates biofilms at a much greater rate using brushing times of 120 seconds vs. brushing times of 30 seconds 18. Thus, the reason why many electronic toothbrushes use an audible 30 second timer to change quadrants totaling 120 seconds. Parents should additionally monitor their child’s exposure time during tooth brushing, as it is critical to preventing plaque buildup. Fluoride is an emotionally charged and controversial topic, but there is enough scientific information to make decisions about relative exposure levels at different developmental stages and during adult years. What is more unclear is the amount that adults need to provide protection against cavity formation yet not cause harm to certain organs or promote certain pathologies/disease processes. Adding fluoride to the water supply has only been practiced for the past 60 years or so, and we don’t yet know if the added fluoride will cause harm over time.
In adults, excess ingestion of fluoride may have deleterious effects on the cardiovascular system 19, skeletal system 20, fertility, gastrointestinal problems and structural/functional damages to the nervous system 21. Thus, there is a reason why fluoride is classified as a nonessential, ultratrace mineral. The interaction between fluoride and thyroid function is extremely complex and highly debatable, as several animal and human studies have shown mixed results. Human biochemistry and metabolism of fluoride is understood, however, and higher levels of fluoride can mimic the actions of thyrotropin (TSH) and could theoretically impact thyroid function. There are urinary tests available in troubleshooting fluoride and thyroid function that I’ve mentioned in the summary section for those who are interested.
In the US, drinking water has been fluoridated using around 1ppm (or 1mg/L) for the past 60+ years due to its cavity-protective effects. Typical concentrations of fluoride in the US water supply ranges between 0.7 to 1.2mg/L. Remember this range, as it will be relevant later on in this paper. A recent cross-sectional analysis of different regions containing different levels of fluoride (found in the water supply) in China found that the regions with higher concentrations of fluoride had a greater prevalence of carotid artery atherosclerosis 22. Liu, et al. conducted an assessment of the relationship between excess fluoride intake from drinking water and hypertension 22 (HTN, high blood pressure). This group discovered a higher prevalence of HTN in the groups with excess fluoride exposure from drinking water. Researchers analyzed four groups exposed to different concentrations of fluoride found in drinking water; .84 (normal), 1.55(mild), 2.49 (moderate) and 4.06 (high) mg/L. The authors noted that the prevalence of HTN in the mild and moderate groups were significantly higher than HTN in the normal group. This shows that we might need to be more careful about our exposure to fluoride.
In this study, plasma ET-1 levels were also found to be higher in the groups with excess fluoride concentrations. ET-1 is a peptide secreted from endothelial cells that plays a role in hypertension. Research on ET-1 is still in its infancy, but elevated levels have been associated with hypertensive populations in some studies 23. Perhaps excess fluoride intake somehow causes an increase in these peptides that may lead to hypertension.
All of these findings would add to the argument for limiting fluoride exposure and prompt further studies in analyzing potential compounds, such as polyphenols, that may protect the teeth from cavity formation. Americans typically consume about 3.4 mg/day of fluoride and if fluoride-containing toothpaste is accidentally swallowed, children could easily exceed recommended intakes 24. The upper intake level (UL) of fluoride is 1.3mg/day for children 1-3 years of age to 10mg/day for children ages older than eight, including adults 24. The Environmental Protection Agency requires that drinking water does not exceed 4.0mg/L 25. If our water supply were fluoridated with 1ppm, or 1mg of fluoride per liter, it would seem sensible to make the public aware of the foods and other hidden sources that may put an adult at risk for exceeding fluoride intakes. Sardines with bones can contain 0.2 – 0.4 mg of fluoride per 3.5 ounces, and other seafood’s such as clams, lobster, crab, and shrimp can contain similar amounts 24.
Ironically, brewed teas tend to contain perhaps the most significant amounts of fluoride. Emekli, et al. analyzed the fluoride content in different brewed tea samples using black and herbal teas produced in Turkey, Sri Lanka, India and Kenya. Herbal teas contained the lowest amounts (0.02-0.04 mg/L) whereas black teas ranged from 0.57 to 3.72 mg/L 26. Cao, et al. sampled and analyzed fluoride concentrations and found that black tea in bags contained the highest amounts of fluoride, all the way up to 6.01 mg L 27. Black teas packaged into teabags are harvested later in the season and have older leaves which contain higher levels of fluoride, which is why these kinds of teas are less expensive. Green teas have lower levels of fluoride than black teas, but more than herbal teas, and still contain relatively high levels of between 1.2-1.7 mg/L 28.
There are currently several toothpastes and mouthwashes on the market than contain extracts such as green tea. I am not aware of any toothpaste or mouthwash containing polyphenols from green tea, black tea, cranberries, or others that have been specifically formulated and established to be clinically effective. However, some of the clinical literature does indicate that fluoride-free toothpaste can control various micro-organisms such as s. mutans just as effectively as fluoridated toothpaste 29.
After looking at the research and speaking to several dentists about the issue, I get the impression that as long as tooth sensitivity is not an issue; it appears that using fluoride-free toothpaste alternatives may be as equally effective at preventing caries. Choosing non-fluoride toothpastes may appear to be prudent in helping to guard against overconsumption/intake of fluoride. Personally, I have stopped using fluoride toothpaste and currently use an alternative formula.
- Non-fluoride mouthwashes and toothpastes are needed to avoid excess fluoride exposure. Polyphenols from a variety of teas and berries such as the cranberry show promise as fluoride substitutes. This is of particular interest to young children, as they are more likely to consume excess fluoride when using fluoridated toothpaste. Conversely, if children are properly monitored and taught proper toothpaste usage, fluoride toothpastes become less of an issue.
- Ironically, teas in general have a high fluoride content, thus it becomes prudent to recommend drinking tea in moderation (1-2 cups per day). As I have covered in previous articles, polyphenols from teas, such as EGCG, can be extracted from the tea and made into a supplement (which does not contain fluoride), which allows the flexibility for clinical doses. For example, to receive the benefits of protecting the eye and brain from oxidative stress, a therapeutic dose may be needed. 1 cup of green tea yields about 200mg of EGCG 30. Drinking between 3-10 cups of tea per day of green tea is the dosage that lines up well with the research that has shown beneficial effects 31, yet may cause dangerous levels of fluoride build up. Thus, supplementation of EGCG becomes a safer and more effective application in such a scenario.
- In some areas of the world where water is not fluoridated, drinking tea may serve as a topical and systemic source of fluoride.
- Avoid consumption of black teas, especially bag teas, and only include them in your diet occasionally. A recent case study (granted, it’s extreme) of a 47 year-old woman who consumed a pitcher of tea containing 100-150 tea bags totaling an estimated fluoride intake of >20 mg/day experienced severe skeletal fluorosis and abnormalities in her skeletal system which lead to the necessary extraction of all of her teeth 32.
- It is difficult to determine intake levels, and nutritional status of fluoride levels. Thus, it remains difficult to determine optimal amounts of fluoride exposures that are helpful in the prevention of cavities, yet do not cause pathology, or influence certain diseases states. For example, many studies on fluoride levels and interruption of thyroid function have been mixed. From a biochemistry standpoint, fluoride can impair thyroid function but since we cannot readily access intake and status, it remains a mystery. However, there are ways to assess whether or not fluoride may be impairing thyroid function through running a 24 hour urinary halides test done through labs such as Doctors Data.
- Different people will react differently to various amounts of fluoride.
- Sarin S, Marya C, Nagpal R, et al. Preliminary clinical evidence of the antiplaque, antigingivitis efficacy of a mouthwash containing 2% green tea – a randomized clinical trial. Oral Health Prev Dent. 2015 Jan 20.
- Eshghpour M, Mortazavi H, Mohammadzedeh RN, et al. Effectiveness of green tea mouthwash in postoperative pain control following surgical removal of impacted third molars: double blind randomized clinical trial. Daru. 2013 Jul 18;21(1):59.
- Maryam HT, Gholamereza A, Maryam H. 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 Isfahan. 2011 Dec;8(Suppl 1):S58-63.
- Influence of cranberry proanthocyanidins on formation of biofilms by streptococcus mutans on saliva-coated apatitic surface and on dental caries development in vivo. Caries Res. 2010;44(2):116-26.
- Linke HA, LeGeros RZ. Black tea extract and dental caries formation in hamsters. Int J Food SciNutr. 2003 Jan;54(1):89-95.
- Marsh PD. Dental plaque as a microbial biofilm. Caries Res. 2004 May-Jun;38(3):204-11.
- Spencer P, Ye Q, Misra A, et al. Proteins, pathogens, and failure at the composite-tooth interface. J Dent Res. 2014 Dec;93(12):1243-9.
- Kopec LK, Vacca SAM, Bowen WH, et al. Structural aspects of glucans formed in solution and on the surface of hydroxyapatite. Glycobiology. 1997;7:929-934.
- Agarwal P, Nagesh L. Comparative evaluation of efficacy of 0.2% chlorhexidine, listerine and tulsi extract mouth rinses on salivary streptococcus mutans count of high school children—rct. ContempClin Trials. 2011 Nov;32(6):802-8.
- Weiss EI, Kozlovsky A, Steinberg D, et al. A high molecular mass cranberry constituent reduces mutans streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite. FEMS Microbiol Lett. 2004 Mar 12;232(1):89-92.
- Girardot M, Guerineau A, Boudesocque L, et al. Promising results of cranberry in the prevention of oral candida biofilms. Pathog Dis. 2014 Apr;70(3):432-9.
- Antunes DP, Salvia AC, de Araujo RM, et al. Effect of green tea extract and mouthwash alcohol on candida albicans biofilm on acrylic resin. Gerodontology. 2014 May 21. Doi:10.1111/ger.12132.
- Tao DY, Shu CB, Lo EC, et al. A randomized trial on the inhibitory effect of chewing gum containing tea polyphenol on caries. J ClinPediatr Dent. 2013 Fall;38(1):67-70.
- Larmas M. Has dental caries prevalence some connection with caries index values in adults? Caries Res. 2010;44(1):81-4.
- Cai YM, Feng XP, Liu YL. The investigation of accidental swallowing of fluoride toothpaste in young children. Shanghai Kou Qiang Yi Xue. 1999 Sep;8(3):150-2.
- Choi AL, Sun G, Zhang Y, et al. Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Environ Health Perspect. 2012 Oct;120(10):1362-1368.
- Watson PS, Pontefract HA, Devine DA. Penetration of fluoride into natural plaque biofilms. J Dent Res. 2005 May;84(5):451-5.
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- Liu H, Gao Y, Sun L, et al. Assessment of relationship on excess fluoride intake from drinking water and carotid atherosclerosis development in adults in fluoride endemic areas, china. Int J Hyg Environ Health 2014 Mar;217(2-3):413-20.
- Dhaun N, Goddard J, Kohan DE, et al. Role of endothelin-1 in clinical hypertension: 20 years on. Hypertension. 2008. Sep;52(3):452-9.
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- Emekli-Alturfan E, Yarat A, Akyuz S. Fluoride levels in various black tea, herbal and fruit infusions consumed in turkey. Food ChemToxicol 2009. Jul;47(7):1495-8.
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