People with swollen gums, missing teeth and other signs of poor dental health are more likely to be infected orally with the human papillomavirus, researchers reported on Wednesday.
HPV, a sexually transmitted virus, causes cancers of the cervix, mouth and throat. The new study, published in Cancer Prevention Research, is the first to document a link between the infection and poor oral health, but other experts noted that the research found only an association and relied mostly on self-reported data about oral health. It is too early to say with confidence that brushing and flossing regularly can prevent oral HPV infection, they said.
The finding is a “modest association,” said Aimée R. Kreimer, an epidemiologist at the National Cancer Institute who was not involved in the study. “We don’t know if poor oral health causes HPV infection and would go on to cancer,” she said.
This finding suggests another potential downside to deficient hygiene “because of a possible association between poor to fair oral health and the presence of the human papillomavirus, which in itself is identified with several diseases,” said Dr. Sol Silverman, a professor of oral medicine at the University of California, San Francisco, and a spokesman for the American Dental Association.
Researchers at the University of Texas Health Science Center at Houston reviewed data on both high-risk and low-risk oral HPV infection and oral health in 3,439 adults, ages 30 to 69, participating in the nationally representative 2009-10 National Health and Nutrition Examination Survey, known as NHANES. The study found that being male, smoking cigarettes, and having multiple oral sex partners increased the likelihood of oral HPV infection, findings similar to those in an earlier analysis of NHANES data.
But after controlling for smoking and the number of oral sex partners, the new study found that self-rated poor oral health was an independent risk for oral HPV infection. The odds of having an oral HPV infection were 55 percent higher among those reporting poor to fair oral health.
Throat cancer caused by HPV is increasing, particularly along middle-aged white men. About 25,000 cases a year are diagnosed in the United States. Many experts believe oral infection with the virus has increased along with the frequency of oral sex.
“What we think might be happening is if you have poor oral health — ulcers, gum inflammation, sores or lesions, any openings in the mouth — that might provide entry for HPV,” said Christine Markham, the second author on the paper and an associate professor of health promotion and behavioral sciences at the University of Texas Health Science Center at Houston. “We don’t have sufficiently strong evidence to demonstrate that conclusively in the study, but that’s our thinking.”
Yet the increase in risk is modest, said Dr. Kreimer, “less than the two- to threefold elevations in risk that cause concern.” And three of the four measures used to assess the participants’ oral health, including the presence of gum disease, were self-reported, a limitation of the study. One measure — number of teeth lost — was reported by dental hygienists.
“It’s the first paper linking self-reported measures of poor oral hygiene and an oral HPV infection,” Dr. Maura L. Gillison, a professor of medicine at Ohio State University, who was not involved in the study. “It’s a strong paper because it’s a first, but does it have public health significance? Should people change their behavior? I would say no.”
Oral cancers caused by HPV are typically found near the tonsils or at the base of the tongue, she added, and it’s hard to see how those regions could be directly affected by periodontal inflammation.
Experts including Dr. Gillison nonetheless called the study an important first step. “Further study — even though it would be expensive and time-consuming — should be considered,” said Dr. Silverman.