In a study done in 2010, Shinga-Ishihara et al. reviewed the effects of xylitol in infants when their mother chewed xylitol gum during pregnancy. The study found that their children were less likely to have colonization of Strep. mutans. In a second paper, “Xylitol Carryover Effects on Salivary Mutans Streptococci after 13 months of Chewing Xylitol Gum,” Shinga-Ishihara et al. took another look at the same study, only this time they analyzed the effects on the mother over the 23 months the study was done.
Out of 400 pregnant women screened for the study, 107 were chosen to participate based on the candidate’s health and recent use of xylitol and/or antibiotics. Researchers excluded a candidate if she used xylitol and/or antibiotics in the month prior to the study or if she had gastrointestinal problems. At the beginning of the study, each participant completed a survey that asked general questions of the woman’s situation including age, expected delivery date, and both dental and smoking histories. All the women were 3-5 months pregnant at the initiation of the study. The researchers split the chosen candidates randomly into two groups: one group would chew xylitol gum daily, the other would not. At the beginning of the study all women received oral hygiene instructions and a professional cleaning. Each group received additional basic preventative measures at their sixth month of pregnancy.
The first part of the study lasted for 13 months. The researchers asked the xylitol group to chew one piece of gum containing xylitol for at least five minutes, four times a day. The women received the gum directly from the researchers and never chewed any other type of gum throughout the study. Periodically, the researchers asked the groups to come in to test the amount of bacteria found in the mouth.
The study concluded that over the 13-month period a large portion of the xylitol group had a decrease in bacteria found in the mouth. This aligns with studies previously done, which found a decrease in bacteria levels in plaque and saliva when xylitol was used [Makinen et al., 1989; Ly et al., 2006; Milgrom et al., 2006]. After the 13-month period, researchers continued to monitor the women for an additional 15 months. During this time the women did not use the xylitol gum. Interestingly, the effects of the xylitol gum were found to be long-lasting in about a quarter of the group, even when they were not chewing the gum. This suggests that there is a “carryover effect of long-term xylitol use” (Shinga-Ishihara et al., 2012).
Citation:

Shinga-Ishihara, C., Y. Nakai, P. Milgrom, E. Soderling, M. Tolvanen, and K. Murakami. “Xylitol Carryover Effects on Salivary Mutans Streptococci after 13 Months of Chewing Xylitol Gum.” Caries Research 46 (2012): 519-22. Pubmed.gov. Web. 25 Apr. 2015.

The Carryover Effects of Xylitol
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