Dental problems in cleft lip and palate linked to abnormal salivary glands

Dr. Timothy Cox, a craniofacial researcher at Seattle Children's Research Institute and lead author, found that mice with a gene mutation that causes cleft lip and palate had problems in their salivary glands that affected gum tissue and oral health.

"We found that the cleft lip and palate gene mutation also resulted in abnormal salivary glands," Cox said. "The result was a mouth environment that was too acidic and contained excess bacteria, which led to problems in the gums and more rapid tooth decay."

In healthy people, salivary glands excrete saliva that contains protective immune compounds and balances the acidity in the mouth. The researchers found that a common cleft lip and palate gene mutation resulted in abnormal development of salivary gland ducts such that they could not properly pump the buffering liquid and protective immune compounds into the mouth.

"No one has systematically looked at salivary glands in cleft lip and patients because it is not part of the typical clinical assessment of these patients," Cox said. "We know saliva contains protective immune compounds that combat tooth decay, and researchers have also observed that some children with cleft lip or palate have different salivary composition. This is a breakthrough because doctors and dentists could use this research to develop improved strategies for managing oral health in young cleft lip and palate patients."

In the study, the researchers offered mice with the cleft lip and palate mutation and mice without the mutation a high sugar diet. After just 8 weeks on this diet, the mice with the cleft lip and palate mutation had almost no molar teeth left, while the mice without the mutation had only mild decay.

The researchers focused on the gene IRF6, the gene most commonly associated with cleft lip or palate. Many other genes have been linked to cleft lip or palate, and the researchers hope to understand if these additional genes are also associated with enhanced tooth decay.

"Doctors who treat children with cleft lip or palate have observed for a long time that tooth decay is a problem, and one that can affect their quality of life," said Dr. Michael Cunningham, medical director of the Craniofacial Center at Seattle Children's Hospital. "It can also be a financial burden on families because many kids require extensive dental care, and eventually orthodontic care."

According to the Centers for Disease Control and Prevention, cleft lip and palate is one of the most common birth defects in the United States. Each year, 2,650 babies are born with a cleft palate and 4,440 babies are born with a cleft lip with or without a cleft palate.

The next steps in the research include studying salivary composition in cleft lip or palate patients, as well as additional genes associated with cleft lip or palate to determine if they contribute to abnormal development of the salivary glands.

"We hope that as the research progresses, doctors and dentists can apply the findings in caring for cleft lip or palate patients and protect their teeth starting in early childhood and into adulthood," Cox said.