As soon as an infant cuts that first tooth, proper dental hygiene is a must. Babies who are put to bed with their bottles and toddlers who tote around sippy cups full of sugary juice all day are at risk of developing a condition called early childhood caries. This bacterial infection, often passed to young children from a caregiver with untreated dental disease, causes aggressive and painful tooth decay. Treatment can require surgery.

Hyun (Michel) Koo, a professor in the Department of Orthodontics in the School of Dental Medicine, has spent his career looking for new treatments for dental caries, which are commonly known as cavities. He has identified promising treatments in compounds derived from cranberries and a material produced by honeybees to protect their hive.

In his latest study, which will be published in the May print issue of Infection and Immunity, he worked with colleagues to better understand what makes early childhood caries so intractable in the mouths of preschoolers.

Researchers generally believed that the bacterium Streptococcus mutans was responsible for the disease, but Koo and others noticed that the fungus Candida albicans was also present in the tooth plaque of children with the condition. The discovery piqued Koo’s interest, because although C. albicans sticks to the cheek and tongue, it was not believed to adhere well to teeth.

Koo and colleagues soon discovered that S. mutans produces a molecule that allows C. albicans to produce a very sticky substance in the presence of sugar.

“The combination of the two organisms led to a greatly enhanced production of the glue-like polymer,” Koo says, “drastically boosting the ability of the bacterium and the fungus to colonize the teeth.”

The gooey plaque formed by the microorganisms has pockets of high acidity, which causes cavities to form in the teeth. When rats were infected by S. mutans and C. albicans together, they had twice as many cavities, which were of much greater severity.

With this enhanced understanding of the cause of early childhood caries, the researchers hope to find ways to intercede and prevent the partnership between fungus and bacteria from leading to tooth decay.

“Our data will certainly open the way to test agents to prevent this disease,” says Koo, “and, even more intriguing, the possibility of preventing children from acquiring this infection.”