We've always been told that tooth decay is irreversible; once the tooth material is gone, it can only be filled with an artificial substance to prevent further decay.

An article on the Family Health Freedom Network site says differently. "Tooth regeneration is possible, and surprisingly simple," writes an unidentified author. Her post describes how good nutrition and the practice of oil pulling not only improved her own oral health, but also healed a badly decayed wisdom tooth in her husband's mouth.
Oil pulling is the practice of swishing an anti-bacterial oil in the mouth for 15 to 20 minutes, then spitting it out. The oil catches the bacteria in the mouth, which is then discarded with the oil. 

Sound crazy? Not quite, says Dr. Jessica Emery, a dentist in Chicago. While she believes that oil pulling is beneficial, Emery does not believe that it can do everything that some proponents claim it can. "Oil pulling does not reverse the effects of tooth decay, and it's important that patients are made fully aware of that," she wrote in an article on Dentistry IQ. "While I certainly can't support every claim that is out there, I do believe that this simple oral health technique will likely improve dental health."

Emery, who practices oil pulling herself, recommends using coconut oil, claiming that 50 percent of the fat in coconut oil is comprised of lauric acid, a "bacteria-whooping ingredient." Gently swish a tablespoon in your mouth for 15 to 20 minutes in the morning, then spit it out into a trash can (not the sink, as oil buildup can cause plumbing issues).

The Family Health Freedom Network author claims to have removed popcorn kernels from her teeth with oil pulling, and Emery says "I do love how my mouth feels after swishing and that feeling lasts for much of the day."

Whether or not oil pulling will turn rotten teeth into pearly whites is a topic for discussion, but Emery believes the practice has definite benefits. "When used in conjunction with regular brushing and flossing, I’m convinced it will actually help you."