It should be remembered that cavities are caused by bacteria. They’re caused by living organisms. Food particles don’t inherently bore holes in your teeth. They provide the potential for bacteria, the breeding ground for their survival. But like other bacterial infections, cavities are contagious.
At first this may seem odd. Cavities are physical holes in a person’s teeth; it’s structural damage like a fractured bone. And you can’t spread your broken leg to another person. However, what people fail to realize, or remember, is the bacterial nature of cavities.
Streptococcus mutans and streptococcus sobrinus are the chief culprits in tooth decay. They thrive on sugar, namely sucrose, which they metabolize into acid in a process known as lactic acid fermentation. This acid is the reason your highly mineralized—and extremely hard—teeth decay. These bacteria are survivors and besides multiplying in your mouth, they can jump to others. Common but not necessarily well-known ways to get a cavity include:
Infants and children are especially susceptible. It has been found that 30% of 3 month old babies and 80% of 24 month old babies had cavity causing bacteria. So even when you barely have any teeth at all these bacteria are making quick work of them.
Obviously, the key to reducing bacteria is regular and proper brushing. Night time, though, is when you’re most vulnerable so get an excellent brushing session in. When sleeping, the body produces less saliva, allowing for bacteria to thrive.
One observation about teeth is particularly fascinating: unlike almost all other exposed surfaces of the human body, teeth do not have a shedding process. Think about it. You shed skin and hair. Indeed, shedding of the stratum corneum (the outermost layer of skin) prevents skin infections caused by fungus and other microbes.
Since teeth do not shed, bacteria tend to persist. Once they have a nice bed of plaque to keep themselves attached, cavity-causing bacteria will be at home in your mouth for a while. So keep up the brushing and keep down the sugar/acid intake. Basically…don’t drink soda.