French kissing can give you cavities

Wrote Anahad O'Connor in his "Really" column in the March 28, 2011 New York Times Science section, "Everyone knows you can catch a cold or the flu. But can you catch a cavity?

"Researchers have found that not only is it possible, but it occurs all the time.

"While candy and sugar get all the blame, cavities are caused primarily by bacteria that cling to teeth and feast on particles of food from your last meal. One of the byproducts they create is acid, which destroys teeth.

"Just as a cold virus can be passed from one person to the next, so can these cavity-causing bacteria. One of the most common is Streptococcus mutans. Infants and children are particularly vulnerable to it, and studies have shown that most pick it up from their caregivers — for example, when a mother tastes a child's food to make sure it’s not too hot, said Dr. Margaret Mitchell, a cosmetic dentist in Chicago.

"A number of studies have also shown that transmission can occur between couples, too. Dr. Mitchell has seen it in her own practice.

"'In one instance, a patient in her 40s who had never had a cavity suddenly developed two cavities and was starting to get some gum disease,' she said. She learned the woman had started dating a man who hadn’t been to a dentist in 18 years and had gum disease.

"To reduce the risk, Dr. Mitchell recommends frequent flossing and brushing, and chewing sugar-free gum, which promotes saliva and washes away plaque and bacteria."

Below, the abstract of the June 2007 study referred to above, published in the Australian Dental Journal, describing Streptococcus mutans transmission from caregivers to young children.

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Factors influencing oral colonization of mutans streptococci in young children

This paper aims to critically review current knowledge about the key factors involved in oral colonization of the cariogenic group of bacteria, mutans streptococci (MS) in young children. MS, consisting mainly of the species Streptococcus mutans and Streptococcus sobrinus, are commonly cultured from the mouths of infants, with prevalence of infection ranging from around 30 per cent in 3 month old predentate children to over 80 per cent in 24 month old children with primary teeth. MS is usually transmitted to children through their mothers, and the risk of transmission increases with high maternal salivary levels of MS and frequent inoculation. Factors that affect the colonization of MS may be divided into bacterial virulence, host-related and environmental factors. Complex interaction among these factors determine the success and timing of MS colonization in the child. As clinical studies have shown that caries risk is correlated with age at which initial MS colonization occurred, strategies for the prevention of dental caries should include timely control of colonization of the cariogenic bacteria in the mouths of young children.

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Below, the abstract of a study published in the journal Oral Microbiology and Immunology in December, 1993, which demonstrated transmission of cavity-causing bacteria between spouses.

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Transmission of oral bacterial species between spouses

The transmission of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and mutans streptococci was studied between 4 married couples who suffered from advanced periodontitis. Of the 20 couples investigated, the 4 in which both spouses harbored A. actinomycetemcomitans and P. gingivalis were chosen for the transmission study. Three of these couples also harbored mutans streptococci. A. actinomycetemcomitans isolates (8-24 per subject) and mutans streptococcal isolates (5-23 per subject) were serotyped by immunodiffusion technique. For ribotyping, chromosomal DNA from A. actinomycetemcomitans isolates (4-5 per subject) and mutans streptococcal isolates (4-11 per subject) was digested with restriction endonucleases ClaI or BglI and HindIII or SmaI, respectively. P. gingivalis isolates (2-15 per subject) were ribotyped by using ClaI, BglI and SmaI. The blotted restriction fragments were hybridized to the plasmid pKK3535, which contains the rRNA operon of the E. coli chromosome. The spouses in 2 couples shared the same sero- and ribotypes of A. actinomycetemcomitans and S. mutans. P. gingivalis ribotypes were identical in 2 couples. The result suggests transmission of oral bacteria between spouses.