Although four out of five dentists recommend Crest to maintain healthy teeth and gums, the fifth dentist, Dr. Isaac Yankem, does not.

Yankem has always been a black sheep of the dental profession — an alleged sadist who takes pleasure in his patients’ discomfort.

His own teeth — a gnarled mess of yellowed chompers — indicate a flagrant disregard for even the basic tenets of oral hygiene.

“If he spent as much time studying dentistry as he spends weightlifting and beating people up, he might have a better reputation,” said Dr. Edwin Leung, president of the American Dental Association.

“Instead of encouraging patients to brush and floss, Yankem has recently been advising patients to ‘embrace the hate,’ whatever that means,” Leung said.

Some of Yankem’s colleagues attribute his nasty attitude to a traumatic household fire during his childhood or something. Nobody, apparently, can quite figure out his real history.