Let me say this, Contrary to popular belief passed down from folklore tales and legends, birds do not brush crocodiles' teeth. Any bird that stays too long, or got caught in that wide opened jaws while the huge reptiles solar-charges must turn to a crispy birdie-barbecue!
Debunking The myth: the folklores and stories are very old ones, it’s been passed down from and since about the 5th century BC. It was a widespread belief that small birds, Egyptian runners (Pluvianus aegyptius), fly into the mouths of crocodiles and pull out food debris stuck in their teeth. As a result of this relationship, the crocodile and the small bird allegedly both benefit: the predator - healthy teeth, and the feathered one - pieces of meat that serve as food for him.
Despite the popularity of this story, there is still no evidence that this really happens in nature. It is likely that this myth arose when a bird was seen catching carrion flies, which flocked to the remnants of rotting meat left on the face or mouth of these giant predatory reptile. And during the hunt of the Egyptian runner, the crocodile may have been lying with an open mouth.
After all, as you know, these predators often do this. According to one scientists, crocodiles sometimes keep their mouths open to: radiate excessive heat out of their body, to cool off. Also, this behavior plays a social function as well as body temperature regulations.
In addition, crocodiles do not need such cleaning of their teeth at all. Indeed, unlike mammals, their teeth change almost throughout their lives. So, in young crocodiles, teeth change every month, and in adults - every few years, and only in very old individuals new teeth stop growing. Thus, a crocodile can change at least 3000 teeth during its life!