[Mechanicos]

From the looks of those teeth they had some pretty amazing dentistry and diet back then...

[Bernard Marx]

Dental mutilation, as mentioned in the article, was commonly practiced.

Deliberate skull deformation as a mark of status goes back into prehistory. In the present U.S. the practice was common among several Indian tribes, including the Choctaw, Chehalis and Nooksack. They practiced head flattening by strapping the infant's head to a cradleboard. The Lucayan people of the Bahamas practiced it and the practice was also known among the Australian Aborigines.

See a Wiki article about the practice here: Cranial Deformation