WASHINGTON, Sept. 13 (Xinhua) -- Your mother was right: The condition of your teeth depends on your dietary and oral hygiene habits, not your genes, according to a new study out Wednesday that looked at the role that genes and the oral microbiome play in the formation of cavities.
"Limiting sugar consumption and acid buildup in the mouth have been part of the dogma of the dental community for some time," said senior author Karen Nelson, president of the J. Craig Venter Institute, whose study was published in the U.S. journal Cell Host & Microbe.
"This work introduces specific taxa of bacteria that can be acquired through the environment and that have the ability to induce cavities," Nelson said.
For a long time, Streptococcus bacteria in the mouth have been linked to the formation of cavities.
In the new study, the investigators took a closer look at specific taxa that are important by profiling the oral microbiomes of 485 twin pairs -- 280 fraternal twins and 205 identical twins -- between the ages of five and 11.
Identical and fraternal twins are a popular method used to separate the role of heritability versus the environment. Identical twins result from one egg that' s been split in two at some time during early pregnancy, whereas fraternal twins result from two separate eggs.
"We decided to focus on children because we hypothesized two things -- that the oral microbiome rapidly changes with age, and also that child twin pairs are likely to have a shared environment," Nelson explained. "This allowed us to better control the influence of shared and unique environments."
Their results showed that identical twins had oral microbiomes that were more similar to each other than those of fraternal twins, indicating that there is genetic contribution to which kinds of bacteria are likely to be present in the mouth.
However, the taxa that were linked most closely to heritability were not the ones that play a role in cavity formation, they noted.
In addition, they found that the heritable strains of bacteria decrease in abundance as people get older, whereas the ones linked to the environment increase.
"An important additional finding was the link between certain bacterial species and sugar consumption," the team said.
"Bacteria that were associated with fewer cavities were in lower abundance in twins who had a lot of added sugar in their food and drinks. In contrast, bacteria that are more common in children who consume a lot of sugar were associated with having more cavities."
The team planned to continue studying the twins over repeat visits to examine changing patterns in the oral microbiome. They are also looking at functional differences in the oral microbiomes of identical and fraternal twin pairs that have various states of oral health.