Early Tooth Decay

When a child is born, the bacteria that cause tooth decay is not present in the child’s mouth. The bacteria that are the major causative agents in tooth decay are mutans streptococci, and to a much lesser extent, Lactobacillus. Tooth decay is an infectious disease and is spread between people by transmission of the bacteria (most notably mutans streptococci) from one person to another. Once the required type of bacteria is transmitted, with current technology it cannot be completely removed from the mouth. This is all relatively old and well accepted science. What is new has to do with how it is transmitted from one person to another and even more interestingly, when, and what effect the timing of transmission actually has.

The kind of bacteria that causes tooth decay used to be considered unable to maintain itself without hard structures (like teeth) to attach onto in the mouth. Recent research has shown that tooth decay causing bacteria can lodge itself in the fissures of the tongue before the teeth arrive. Early colonization by mutans streptococci is a major risk factor for developing cavities in the teeth later. Children whose mouths were found to have been colonized with the tooth decay causing bacteria at age two on average had over three times as much tooth decay by age four years as those children whose mouths were not colonized at age two years. It was also found that 89% of children whose mouths were colonized by mutans streptococci by age two had experienced at least one site of tooth decay by age four versus only 25% of children whose mouths were not colonized with mutans streptococci before age two. (This information was obtained from an article entitled Acquisition and Transmission of Mutans Streptococci printed in The Ontario Dentist Jan/Feb 2009 which reprinted the original article by Dr. Robert Berkowitz from the California Dental Association). What this means is that early colonization of a child’s mouth by mutans streptococci is a major risk factor for future development of cavities in the child’s teeth.

It has long been known that the major source of mutans streptococci for a child is from their mother. Now here is the real take home lesson: Reduction of the mother’s mutans streptococci clearly showed that infection of the baby could be prevented or delayed. Of course, prevention of transmission of mutans streptococci would mean no cavities for the child. Delayed transmission would mean fewer cavities for the child. It’s not just mom who transmits the tooth decay causing bacteria to the child. Other family members or even other children at the daycare also transmit the bacteria. However, the main source of the bacteria for the child is mom.

So what might a new mother do to prevent or delay transmission of mutans streptococci to her child? First of all, decayed teeth are huge storehouses for mutans streptococci. Before the baby is born, get the decayed teeth fixed or removed. In an infected person (which virtually every adult human is), dental plaque (the soft white stuff on your teeth) is loaded with mutans streptococci. New mothers need to brush and floss. More often is better for all of us, but for new mothers, more often could be all it takes to delay transfer of mutans streptococci until later when the subsequent damage to the teeth will be much less. So, get your teeth fixed before the baby comes, and brush and floss twice or more every day until the child is two. As well, a 30 second rinse with full strength Listerine after brushing and flossing in the morning would certainly reduce the mutans streptococci count in mom’s mouth, at least for a while. This information is presented to illustrate some of the science that is evolving in dentistry and how that science can make the lives of everyone better. Ask your dentist if you want to know more about prevention of tooth decay in children.


Dr. Michael G. Christensen is the original author of each of the articles on this list. Each of the articles was printed between 1999 and 2010 in either the "Daily Miner and News" or "The Enterprise" which are both newspapers in Kenora, Ontario.