A dental riddle.
There's another, seemingly mystical, anti-cavity benefit attributed to the long-term, regular consumption of xylitol.
This effect is one where the decay protection established for the mother is passed on to her child, even though the child has no history of consuming xylitol at all.
Here's the proof.
As evidence, consider the following research findings [Isokangas (2000)].
- Mothers who had a statistically high level of cariogenic (decay causing) bacteria in their saliva were selected as a study group.
- A subgroup of these mothers was instructed to begin a xylitol regimen (about 7 grams per day via the use of chewing gum) starting three months after the birth of their child.
- At a point two years after childbirth, they were then instructed to stop their xylitol use.
The children of all of the mothers were then examined annually for tooth decay up to the age of five years. These examinations revealed that the children of mothers who had used xylitol experienced decay rates that were close to 70% less than the children of mothers who did not.
When reading the above, keep in mind that the xylitol was only consumed by the mothers, the children themselves never received any at all. Also take notice of the fact that their regimens were only started after the birth of their child.
A slightly different study, same general results.
To shed some light on the mechanism that's associated with this effect, we'll mention the findings of a second study.
Solderling (2000) selected a group of pregnant mothers who demonstrated elevated levels of cariogenic (decay causing) bacteria in their saliva. One subgroup of these participants was instructed to use xylitol chewing gum at least two to three times per day, starting three months after they had delivered their child.
The saliva of all of the children was evaluated for the presence of cariogenic bacteria at specific points over the next two years. It was found that the children of the mothers who had consumed xylitol tested as having significantly reduced levels of these bacteria, as opposed to those who had mothers who did not. (Once again, keep in mind that none of the children received any xylitol exposure at all.)
A follow up study determined that even at age 6 the counts of cariogenic bacteria in the saliva of these children were still significantly lower. (The assumption is that they are at reduced risk for tooth decay because the number of cavity-forming bacteria in their mouth is lower.)
How is this phenomenon explained?
So how does this mysterious anti-cavity protection take place when it is only the mothers of the children that received the preventive treatment? The answer has to do with how children initially acquire the bacteria that are responsible for causing cavities.
The following theory provides an explanation of how a mother's consumption of xylitol can reduce the decay rate of her child.
In most cases, the bacteria that are responsible for causing tooth decay are initially acquired by children from their mother via her saliva. This event typically takes place during that time period when the child's first teeth first start to come in, age 6 through 30 months. (It happens this late in the child's life because the bacteria require exposed tooth surfaces to live on.)
It's been found that after the initial bacterial colonization of a tooth's surface has taken place, the continued presence of the same type of bacteria on the tooth is essentially permanent. Their replacement later on by other types of bacteria typically does not take place.
Xylitol use (in this case, by the mother) has detrimental effects on the types of bacteria that cause cavities (termed "cariogenic" bacteria). Due to this, it's more likely that the initial types of bacteria that are transferred to the child's teeth (and therefore their permanent inhabitants) aren't harmful ones. Or else they are in fact cariogenic bacteria but they are more likely to be less harmful (xylitol-sensitive) strains. Either of these scenarios places the child at reduced risk for cavity formation.
Pretty amazing. (There's no way anyone reading the first part of this page expected this explanation as the answer to this riddle.)