'Money' Mayweather pays $25,000 per mouthguard

When it comes to protecting his million-dollar smile, Floyd "Money" Mayweather puts his money where his mouth is.

The boxer, who is preparing for the biggest bout of his career, on May 2 versus Manny Pacquiao, spends more than $25,000 per mouth guard, according to his longtime dentist. But $25,000 doesn't just buy any mouthguard. For Mayweather, it means extravagant, one-of-a-kind designs, extensive testing and cross-country trips for on-site fittings at his Las Vegas gym.

"We have done mouthguards with jewels, gold flakes, guards that match three of his cars, you name it," said the boxer's dentist, Dr. Lee Gause, owner of Iceberg Guards.

Read MoreAaron Hernandez: Ex-NFL star gets life without parole

"Floyd is on another level with what he requests," he said.

Gause's latest work features a clear mouthguard stuffed with a $100 bill that peeks through. It was inspired by Mayweather's business acumen and the big money surrounding the fight.

"Floyd is rocking the charts not only from a sports standpoint, but also from a business standpoint," said Gause.

The May 2 fight is already breaking records. Priced at $89 for standard defintion pay-per-view, and $99 for HD on PPV, it's the most expensive fight in history.

Read More16 percent of retired NFL players go bankrupt: Study

Tickets for the event on the secondary market average $10,122 and run to $67,000 for a ringside seat, according to TiqIQ. According to some estimates, Mayweather could bank more than $120 million from the fight, which will secure his place as the highest-paid athlete in the world. Mayweather has earned more than $400 million in the ring since turning pro in 1996, according to Forbes.

As the 38-year-old, undefeated, five-time world champion prepares for what's being called "the Fight of the Century," Gause and his team have been at work to ensure his mouthguard fits perfectly and is comfortable come fight night.

Iceberg Mouthguards
Source: Iceberg Mouthguards
Iceberg Mouthguards

"When I go back and look at the (Miguel) Cotto fight, Cotto was choking on his mouthguard, gasping for breath and repeatedly taking it out of his mouth while Mayweather was in his corner speaking with his mouth guard in, drinking water—never taking it out," said Gause, who says his mouthguards enhance air flow.

Gause and his team start with an impression, then mold the guard and fly to Las Vegas to put it to the real test. Mayweather practices everything from fighting to jumping rope with his mouthguard in, providing feedback on its fit. Up to 10 models later, and after customization, the mouthguard is ready for primetime.

The $25,000 price tag may seem steep, but it requires hours of work.

"If you count the hours of labor, the travel, the cost it takes to get to the final mouthguard … it's not really charging a lot money," Gause said. Typically, he charges $260 for a custom guard.