Some people swear by the practice, but little research exists to back up health claims
"Between a teaspoon and a tablespoon is fine. There is no exact amount of oil that must be put in your mouth," he said.
While Halpern said he believes swishing oil is safe, he recommends that people work with a trained and experienced Ayurveda practitioner to get a personalized "prescription" for the type of oil that best fits their needs and physical make-up.
Lydia Hall, a spokeswoman for the American Dental Association, said the association can't comment on oil pulling because additional research is needed. And the National Institute of Dental and Craniofacial Research isn't doing any research on oil pulling, said its spokesman, Bob Kuska.
Some experts say almost anything you do for your mouth is better than neglecting it.
"Anyone who wants to pay attention to their oral hygiene, it's a good thing," said Dr. Joseph Banker, a cosmetic dentist in Westfield, N.J. "But are there other things that they could be doing? Probably."
Many "old remedies" were developed when there was no toothpaste, mouthwash, floss or toothbrushes, Banker said. Nowadays, inexpensive and widely available tools make it a lot easier to take care of your teeth and gums, he added.
As for whether swishing can whiten teeth, Banker is skeptical. "I don't think the oil has an intrinsic effect other than the removal of plaque. It's hard to find a study that states that. Anything that swishes around for 20 minutes may have some effect, even water."
Yet if done daily, oil pulling may remove some tooth stain, Banker said. Also, if the process improves gum health, they will be pinker, which can often make the teeth look whiter, he said.
Banker recommends that people who want brighter teeth simply use whitening strips. "They're easy to place, and you can stop using them if your teeth get sensitive."
But could swishing do harm? "No. It's the ones who ignore their mouths that have problems," said Banker.