Dear Dr. Nelson,

I was told a mother can give a child cavities because they are contagious… is this true?

     Kristen Davis | Glastonbury, CT

Dear Kristen,

As strange as it may sound, the statement that “cavities may be contagious” is not too far from the truth. But I think the most helpful answer will first include a quick review of how and why we get cavities.

Cavities of the tooth (also referred to in the medical community as “caries”) are caused when certain types of bacteria are introduced to the mouth. The most common carie-causing bacteria is Mutans Streptococci (MS for short), but there are others as well.

Bacteria + plaque = a destructive tooth attack
When teeth develop plaque, these harmful bacteria colonize in numbers on the “sticky” plaque coating. This concentrated population of bacteria ingest food particles, and as a byproduct, release acids that eat away at tooth enamel and eventually tooth structure. The result is caries, or tooth cavities and decay.

These destructive bacteria are also pretty durable, and can be spread from one individual to another through the interchange of saliva. So while a “cavity” in itself is not contagious, the bacteria that causes it is transferrable.

So just how does “MS” bacteria find its way to a mouth?
The good news: we are not born with MS bacteria in our mouth. The not-so-good news: its presence means we were exposed and “infected” by someone who did have the bacteria. This usually happens during an activity where, knowingly or not, (and please excuse the icky phrase here) we somehow “swap spit.”

Certainly the first thing that comes to mind with adults may be passionate kissing—but if we stop to think about the daily routine that a mother and child share, it is easy to see how this unfortunate exchange of bacteria can also occur.

Early prevention van provide lifelong benefits
Medical studies conducted on this topic revealed that some children contact MS bacteria within the first few months of life. Additional medical studies concluded that this occurrence set a child up for early and even lifelong bouts with fighting tooth decay unless preventive and corrective measures are administered.

If you or someone you know is the mother of an infant or small child, here are some DOs and DON’Ts than can help prevent the spread of cavity-causing bacteria to young children:

The DON’Ts

Don’t cut a child’s food into smaller pieces by biting it in half with your teeth. This goes for grapes, bananas, etc.

Don’t clean off a dropped pacifier or baby bottle nipple by putting it in your mouth first. It might seem noble at the time, but it’s really just a shuttle ride for MS bacteria.

Don’t blow on your child’s hot food to cool it off. Bacteria are microscopic in size and can be airborne-transferred even if not visible.

Don’t lick the corner of a napkin or your finger to clean off your child’s mouth after eating.

Don’t let your child stick fingers into your mouth and then back into his or her own.

Don’t share an eating utensil with your child.

The DOs

Do try to avoid the “DON’Ts” above and minimize or eliminate the sharing of saliva if and whenever possible.

Do schedule regular dental check-ups and cleanings when pregnant and after your child is born.

Do review your daily hygiene routine with your dentist to make certain your are doing all you can to reduce the bacteria count in your mouth.

Do chew Xylitol gum during pregnancy and after baby is borne. Medical studies have proven that chewing Xylitol gum inhibits the growth of MS, thereby reducing the risk of spreading it.

Certainly, no child can be made totally immune to contacting MS bacteria. So if you have young children that do have cavities, please don’t be hard on yourself. The truth is their contact with bacteria could have happened through either parent, a sibling, relative, or even another child.

The most important thing to remember is that it’s never too early to start your child practicing healthy oral hygiene habits that include regular dental check-ups.

REFERENCES
Davey, A.L. and A.H. Rogers, Multiple types of the bacterium Streptococcus mutans in the human mouth and their intra-family transmission. Arch Oral Biol, 1984. 29(6): p. 453-60.

Kohler, B., I. Andreen, and B. Jonsson, The earlier the colonization by mutans streptococci, the higher the caries prevalence at 4 years of age. Oral Microbiol Immunol, 1988. 3(1): p. 14-7.

Soderling, E., et al., Influence of maternal xylitol consumption on mother-child transmission of mutans streptococci: 6-year follow-up. Caries Res, 2001. 35(3): p. 173-7.