Are dental cavities contagious?
The bacteria that makes you much more likely to get cavities (caries) is contagious, so the answer is yes:
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.
Source: “Factors influencing oral colonization of mutans streptococci in young children.” from Aust Dent J. 2007 Jun;52(2):93-100; quiz 159.
You don’t have to get it from mom — you can also get it from your significant other:
“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.“
Source for that quote (and for more info check out): New York Times
Could a single sneeze make you change your mind about health care?