A warning about a new trend in teeth whitening.

FOX's Lisa Lacerra reports: 

It's gotten more than 1.5 million views on YouTube, the video calls for smearing a charcoal derived mixture on teeth to whiten them:

(Genevieve) "And you're simply going to open up the capsule carefully and pour the contents onto your toothbrush."

Host Genevieve brushes her teeth for several minutes, then rinses:

(Genevieve) "So believe it or not, all that black powder does result in whiter teeth."

Dentists warn the method may lead to enamel deterioration and tooth erosion and the American Dental Association has not yet evaluated or approved any charcoal teeth whitening products.

Lisa Lacerra, FOX News.