Mouth Bacteria (not sugar) Are Rotting Your Teeth

Bacteria attacking our teeth.

Can you imagine a world without flossing?  Until I heard the radio announcer on BBC say that a new type of gum could make flossing a thing of the past, I’d always assumed, based on the conventional wisdom, that evil mouth bacteria that thrived on plaque ate holes in your teeth.  And I’d learned that the best way to combat cavities was to avoid plaque-creating sugar, brush two times per day and floss frequently.  Science is now taking another look at these long-held assumptions.

Both tooth decay and gum disease are caused by an overgrowth of aggressive oral bacteria, Streptococcus mutans (S. mutans).  Very quickly after eating sugar, sticky glycoproteins adhere to your teeth. S. mutans can stick to the glycoproteins.  S. mutans digests fructose in the mouth to create energy.  Lactic acid is a byproduct of their metabolic process.   It is the lactic acid that causes cavities by dissolving the calcium phosphate in tooth enamel.

Traditional methods of fighting tooth decay include brushing and flossing the teeth to physically remove S. mutans from the tooth surface, eating a calcium rich diet, taking fluoride to strengthen tooth enamel and reducing the amount of sugar in the diet to starve the bad bacteria.  All of these methods have been shown to be somewhat effective, but have not completely gotten rid of the problem.  Certain people seem to be cavity-ridden, no matter how good their diet or oral hygiene.

To make matters more complicated, it has been shown that the bacterial infections that cause tooth decay are actually contagious.  They can be passed from parent to child by kissing the child or sharing eating utensils.  (Yet, more fodder for already guilt ridden modern parents!)

Recent scientific focus has led to some interesting new ways to fight tooth decay by targeting the S. mutans and by changing the mix of bacteria and alkalinity in the mouth.

Probiotics

Although the bulk of the discussion around probiotics relates to gut health, there has also been some research into the friendly bacteria that colonize our mouths.  This makes a lot of sense, as the human mouth is such a warm, wet and hospitable home for bacteria of all kinds – both good and bad.

Several studies have shown that probiotics containing certain lactobacilli or bifidobacteria could reduce the number of S. mutans streptococci in saliva.1  With fewer S mutans in the mouth, this could lead to fewer cavities.  However, the studies were small and not particularly conclusive.

In 2006, a German company, BASF, has developed a new bacterium, Lactobacillus anticaries (L. anticaries).  It has been added to gum and marketed as a cavity fighter.   Although this is an exciting claim, I wasn’t able to find any non-BASF funded research verifying its effectiveness.

The research that has been done on trying to get probiotics to colonize the mouth has shown that this can only be done by introducing them directly into the mouth via food or food additives. There is no evidence either that the effects last longer than the period during which you are actually consuming the probiotics.  Long-term colonization by the good bacteria hasn’t yet been proven.

There are however, many probiotic products on the market today that claim to prevent cavities, among other mouth woes like gingivitis and bad breath.  Many people have written books about the cavity preventing properties of probiotics prevent cavities.  There is no reason to believe that it isn’t possible to improve oral healthy with probiotics, but the proven science is not there yet. Further research may find more effective strains of beneficial bacteria or a better method of delivery for long-term colonization.  Xylitol seems to be a more promising cavity fighter, given what we now know.

Xylitol

Xylitol is not a probiotic.  It is sugar, which has been shown to be very effective at preventing cavities.

Xylitol is a naturally occurring sugar that is found in trees, fruits and vegetables. You may already be familiar with Xylitol as it is a commonly used sweetener that can be found in gum and other products and has been approved as a food additive by the FDA since 1963.  It has 40% the calories of sugar and can be eaten by diabetics.   In its naturally occurring form, it has been shown to be safe and there is no apparent link between Xylitol and cancer.

Dr. Ellie Phillips, the dentist interviewed in the BBC story above, and many other researchers believe that Xylitol is the answer in the fight against tooth decay.  When a person puts Xylitol in their mouth, it dissolves in saliva and the S. mutans bacteria absorb it.  But unlike with sugar, the bacteria cannot make energy from the Xylitol.  The bad sugar bugs use additional energy trying to expel the Xylitol from their cells. This essentially starves them – leaving insufficient energy for reproduction.   They also form clumps when exposed to Xylitol, so they can’t stick to teeth as easily and are easier to to clean away with brushing.  Many S. mutans die when they are exposed to Xylitol.  Xylitol also makes the mouth more alkaline and causes increased saliva to be produced, both of which create an inhospitable environment for cavity causing bacteria.

There have been many research studies that have shown Xylitol’s effectiveness.  The American Academy of Pediatric Dentristy  (AAPD), in its Guidelines on Xylitol Use in Caries Prevention,  recommends the use of Xylitol to reduce cavities.  It has written about Xylitol that it is particularly effective for cavity prevention when taken when children’s teeth are erupting.  One randomized study showed that eight grams of Xylitol syrup per day decreased cavities in children aged 15 – 25 months by 50 – 70%.2  Long-term benefits3 have been seen from regular Xylitol use for up to 5 years after stopping the Xylitol. 4 And for those of you worried about giving bad cavity bacteria to your children, it has been shown that long-term use of Xylitol by the parents, can actually prevent small children from getting cavities!5 This is very exciting stuff.

One of the challenges with Xylitol as a tooth decay fighter is that it takes fairly high and frequent doses to have the desired effect.  The AAPD recommends taking 3 – 8 grams total daily, preferably broken into at least three doses per day.6

There are many commonly available products containing Xylitol that can be found in grocery stores, drug stores and health food stores.  There are lots of different kinds of readily available delivery methods – syrup, chewing gum, mouthwash or lozenges. Gum seems to be more effective than lozenges.  Some bright entrepreneur has invented a pacifier with a pouch containing slow-release Xylitol! But this has not yet been approved in the US. 10% Xylitol toothpaste, which has been shown to be effective, is currently available outside of the US only.

Summary

Saying goodbye to flossing seems like a stretch, but maybe now we can feel slightly less guilty about not doing it the recommended two times per day.  Even if it isn’t that effective against cavities, it is surely good at removing pieces of uncomfortable smelly, rotting food from your smile.

After researching this topic, I will be buying some gum containing therapeutic doses of Xylitol for my family – that is if I can find gum to buy in Singapore!  We’ve been pretty lucky with cavities – only one filling for one of my sons, but I’d like to keep it that way.  And after the time and expense of orthodontia, there’s extra incentive to keep those choppers healthy.

If any of you have any experience with Xylitol or with mouth probiotics, I’d really be interested to hear from you about your experience in the comments below.

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1. Eur J Dent. 2010 July; 4(3): 348–355 [↩]
2. Milgrom P, Ly KA, Tut OK, et al. Xylitol pediatric topical oral syrup to prevent dental caries. Arch Pediatr Adolesc Med 2009;163(7):601-7 [↩]
3. Isokangas P, Mäkinen KK, Tiekso J, Alanen P. Long-term effect of xylitol chewing gum in the prevention of dental caries: A follow-up 5 years after termination of a prevention program. Caries Res 1993;27(6):495-8 [↩]
4. Hujoel PP, Mäkinen KK, Bennett CA, et al. The optimum time to initiate habitual gum-chewing for obtaining long-term caries prevention. J Dent Res 1999;78(3):797-803 [↩]
5. Thorild I, Lindau B, Twetman S. Effect of maternal use of chewing gums containing xylitol, chlorhexidine or fluoride on mutans streptococci colonization in the mother’s infant children. Oral Health Prev Dent 2003;1(1):53-7 [↩]
6. Ly K, Milgrom P, Roberts M, Yamaguchi D, Rothen M and Mueller G. Linear response of Mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial. BMC Oral Health 2006, 6:6 [↩]