Rossman said his wife alerted him to the stains and after doing some internet research he discovered that the same complaint had already been made by a number of other consumers, an Associated Press report said.

P&G has not responded directly to the lawsuit, although it did say that '99.9 'of product users had not complained, and even ventured to claim that the tooth stains might be a sign the product is working.

Rossman has filed a class-action lawsuit against the company in Michigan, claiming that P&G is violating the state consumer protection act.