(Chayapon Bootboonneam/EyeEm/Getty Images)
Because they need space. Each tooth has its time of formation and eruption. Wisdom, or third molar, begins to form around 5 years old and is only born between 15 and 20 years old. After all, it would be impossible for a child’s mouth to house all the teeth at once. The problem is that this body “strategy” does not always work, as the dental arch can expand and occupy the piece of gum that would be destined for the wisdom teeth.
“This happens because of the reduced size of the upper jaw or mandible, or because of a bad positioning of the teeth that were born before”, says dentistry professor Roger William Moreira, from the State University of Campinas (SP), Unicamp. When space is lacking, wisdom teeth press on neighboring teeth, causing pain and inflammation, and sometimes need to be pulled out.
But this early adult episode wasn’t always a nuisance. “Our ancestors had a more consistent and abrasive diet and early tooth loss was frequent, which made third molars fundamental to complement the masticatory system”, says Roger. Today the situation is different. Jaws have shrunk, diets are lighter and wisdom teeth are almost useless. “Some people don’t even have these teeth anymore, which indicates an evolutionary tendency for them to disappear”, says dentistry professor Marcelo Giannini, also from Unicamp.