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Delta Dental Newsletter Extols the Virtues of Xylitol amet, Consumers looking for additional ways to fight cavities and promote their oral health may have found a friend in an increasingly popular sugar substitute.

Effects On Oral Ecology:
clinical studies in children and adolescents
Xylitol is a natural carbohydrate like substance. The industrially produced xylitol molecules have the exact same structure as the molecules that occur naturally and in humans.
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From: Xylitol Sweeten Your Smile
by John Peldyak, DMD

Studies using xylitol as either a sugar substitute or a small dietary addition have demonstrated a dramatic reduction in new tooth decay, along with arrest and even some reversal of existing dental caries. Xylitol provides additional protection that enhances all existing prevention methods. This xylitol effect is long-lasting and possibly permanent. Low decay rates persist even years after the trials have been completed.

Causes of Tooth Decay

Dental caries (tooth decay) is a multifactorial disease process. Enamel, the mostly inorganic hard outer tooth layer, is dissolved (demineralized) by acids produced from sugars by plaque bacteria. Bacteria can more rapidly invade and eat away the inner dentin layer because it is softer and contains more organic material. The tooth surface is in a dynamic state of flux between demineralization (destruction) and remineralization (repair). Acid conditions (lower pH) favor the loss of calcium and phosphate from the tooth while neutral or alkaline (higher pH) conditions help to replace minerals, as illustrated by the "Stephan Curve":

Individuals susceptible to tooth decay tend to have less buffering capacity against plaque acid. Their saliva pH tends to drop lower and recover more slowly. Demineralization predominates at lower pH, beginning (somewhat arbitrarily) at 5.7. Thicker plaque helps to hold acid against teeth and leads to surface destruction that begins in localized sheltered areas.

Tooth decay occurs at the intersection of the necessary elements: bacterial plaque acids dissolving a susceptible tooth over time. Xylitol interferes with all of the destructive elements and helps to tilt the balance in favor of dental protective factors.

Xylitol is non-acidogenic and non-cariogenic. Xylitol is essentially non-fermentable and therefore cannot be converted to acids by oral bacteria. Xylitol can be left on the teeth overnight and not cause any damage. With proper us xylitol can stop the formation of tooth decay (cariostatic). Xylitol is not merely an inert bystander but can exert an active counter force to decay (anticariogenic). This depends upon how the xylitol is used. The delivery method, the amount, the timing, and the frequency are important. Xylitol can enhance the remineralization or healing process. This happens best in small decay spots just beginning in the enamel. Larger holes won’t go away and will still require a filling or restoration, but they can harden and become less sensitive.

Xylitol use after meals and snacks in products that encourage chewing or sucking:

• stimulates saliva
• enhances protective factors in saliva
• stabilizes calcium and phosphate solutions
• encourages remineralization
• raises plaque pH
• reduces time teeth are exposed to demineralizing acids
• inhibits bacteria
• reduces plaque
• reduces contact time of sugars on teeth
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Decay Prerequisites

1. Tooth (host susceptibility)
   Poor nutrition or illness during tooth formation can lead to defects in enamel. Lack of saliva diminishes healing potential. Xylitol stimulates saliva flow and helps to keep salivary minerals in a useful form. Prolonged xylitol use increases the buffering capacity and protective factors in saliva. Teeth that erupt during xylitol use seem to be well-mineralized and impervious to decay.
   
   
2. Time
   Teeth don’t go to sleep healthy and wake up riddled with cavities. Tooth decay is a process that takes time because enamel is very sturdy material. The organic acids produced by bacterial fermentation are relatively weak and they eat away at enamel slowly. Using xylitol helps to raise plaque pH and thereby reduce the time that teeth are exposed to damaging acids.
   
   
3. Diet
   Tooth decay does not occur without fermentable carbohydrates in the diet. Simple sugars cause more caries that starch, and sucrose (table sugar) causes the most. Some foods tend to inhibit decay. Examples are fat (in general), aged cheese, peanuts and certain proteins and minerals. Total-amount-of-sugar-consumes is NOT as important as other factors such as frequency, timing, adhesiveness, concentration, and texture. Large amounts of sugar can be eaten with meals and not damage the teeth, whereas much smaller amounts of sugar retained on the teeth can be devastating.
   
   Dentists recognize the futility of advice to avoid sugars. It is behaviorally unrealistic and besides, any frementable carbohydrate can contribute to tooth decay. Even folks who claim they eat "no sugar" may expose their teeth to significant sources from honey, malt syrup, rice syrup, fruits and even medications. Given enough time, salivary enzymes can break down starch into simple sugars.

   Replacing all dietary sugars, or even just the "accessible" sugars in the diet with xylitol is expensive and impractical. Thankfully it is also unnecessary. Just a little bit of xylitol in chewing gum (or in a form that can be kept in contact with the teeth for awhile), is all that is needed to blunt the "acid attack" after eating. Consistently using small amounts of xylitol tends to increase protective factors in saliva and help maintain pH in the safe range above 5.7 (see graph—xylitol use can increase plague pH by almost 2 unites in this hypothetical snacker).
   
   Oral pH becomes less acidic with continued xylitol use. There is more saliva with greater buffering capacity so demineralizing conditions seldom occur. Because saliva productions decreases during sleep, xylitol should be used after late-night snacks or medications (syrups and chewable tablets often contain
   sugar).

4. Germs?Cariogenic Bacteria
   Germ-free animals do not develop dental caries no matter how much sugar they consume. Those of us who don’t live in sterile bubbles harbor plenty of varieties of mouth bacterial. Most of these are harmless. The villains are those bacteria that can tolerate acid conditions (aciduric) while they continue to ferment sugar to produce more acid (acidogenic).

   Introducing: Streptococcus mutans…(Strep mutans or S. mutans) This group of bacteria is the principal instigator of dental caris. There is so much genetic variation that the whole
   bunch is sometimes referred to as "the mutans group of streptococi" or ms.

   Nasty characteristics of ms:

   • Aciduric—thrive at low pH that inhibits other bacteria
   • Acidogenic—continue to generate acid even at low pH
   • Form sticky polymers (extracellular polysaccharides) from sucrose
   • Tenacious adherence to hard surfaces (like teeth)
   • Store excess sugar inside their cells (intracellular polysaccharides)
   • Ability to ferment sorbitol and mannitol—Uh oh, these are sweeteners found in many "sugarfree" products, including toothpaste!
     

   Other bacterial groups are also associated with tooth decay. For instance, some varieties of lactobacilli are known as
   "secondary invaders", found deep in active caries.

   Xylitol is virtually non-fermentable by oral bacteria. With constant use, the low pH niche begins to disappear as the
   cariogenic germs are crowded out by harmless bacteria.
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Not All Dental Plaque Is The Same

Dental plaque is populated by many varieties of bacteria. Only some of these, like ms, cause disease. Plaque fed high-test "fertilizer" like sucrose (sugar) becomes extra harmful as bacteria ooze a meshwork of sticky goo (extracellular polysaccharides).

Long term use of xylitol suppresses the nastiest gangs of bacteria, making a long-lasting, possibly permanent, change in those bacterial communities. The result is a kinder, gentler plaque that produces less acid and fewer toxins and antigens (immune challengers). It contains more natural cleaning enzymes and minerals for tooth repair.

During the past several years there has been a shift away from the general plaque hypothesis toward the specific
plaque hypothesis.

GENERAL PLAQUE HYPOTHESIS

• Plaque is Plaque is Plaque
• Plaque is bad.
• Everybody has plaque—no diagnosis needed.
• Get rid of it.
• Bacteria are bad—kill them.
• Mechanical Treatment:
• --Drill & Fill
• --Recheck in six months

SPECIFIC PLAQUE HYPOTHESIS

• Different plaques have different ecologies
• Some plaques are worse than others.
•  Diagnosis is essential to identify risk.
• Modify it.
• Some bacteria are useful. Just eliminate the pests.
• Medical Treatment:
• --Address the underlying problem
• --Test to Make sure the pests are gone

Xylitol should make both groups happy. Regular xylitol use leads to less plaque and less plaque acid. Additionally, it results in the specific inhibition of ms, thereby modifying the remaining plaque and preventing the overgrowth of harmful bacteria.
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Xylitol and Gum Disease

Gingivitis is an inflammation of the soft gum tissues that can lead to more serious periodontal disease involving the breakdown of supporting connective tissues with progressive, intermittent destruction of the jaw bone that surrounds tooth roots.

Plaque accumulations are believed to be the primary cause of gum disease. Tarta (dental calculus) is a hard but porous mineralized plaque that acts as a matrix for additional soft plaque build-up.

The most direct way to control gum disease is by mechanical plaque and tartar removal. Good oral hygiene needs to be supported by a diet adequate in essential nutrients such as protein, vitamins and minerals.

Regular xylitol use leads to lower plaque accumulations. The use of anti-plaque substances does not necessarily guarantee less tartar. For example, chlorhexidine effectively reduces plaque but it can also increase calculus accumulation. Xylitol forms weak interactions with calcium in solution, helping to prevent precipitation. This stabilizing effect of xylitol make salivary calcium available for remineralization of enamel while slowing the rate of tartar formation.

Thick plaque blocks out oxygen and saliva, favoring harmful anaerobic bacteria. Less plaque is, by itself, a useful xylitol effect. Xylitol can also modify the plaque to make it periodontally less harmful. Xylitol plaque is less adhesive, less irritating and less inflammatory than sucrose plaque. Xylitol does not support the growth of any of the bacteria associated with periodontal disease and may be inhibitory.
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