What about the other 40 percent?

"So," you are probably asking yourself, "if my genes are 60 percent of my cavities, what governs the other 40 percent?"

Answer: Soft drinks and fluoride.

OK, that might be a slight exaggeration. The other 40 percent has to do with environment: diet, brushing frequency, smoking habits, dental care access, culture, even socioeconomic factors, according to Robert J. Weyant, chairman of the University of Pittsburgh's Department of Dental Public Health.

But so far, the single biggest environmental factor scientists have identified that encourages tooth decay is the consumption of sugary drinks, Weyant said. Any sugary treat can hurt, but sugary drinks are particularly adept at spreading sugar to every corner of your mouth to feed the bacteria that cause decay.

Tea and coffee don't even rate in comparison. Alcohol is not even on the list. In fact there is very little to suggest that alcoholic drinks have any significant effect on tooth decay -- unless, of course, you like to drink your whiskey in a large glass of soda.

On the opposite side, the single biggest environmental factor known to protect against tooth decay is fluoride. Get it in your city water supply, get it in your toothpaste, get it in periodic treatments from your dentist, but get it somewhere. That is the consensus among dentists and public health experts alike, Weyant said.