Dental development can determine a juvenile's age as children's teeth erupt at almost exactly the same rate. Furthermore, the pattern of development can be studied to determine the age. Dentition over time can wear away and can be used to determine age but diet also plays a hand in tooth wear. In newborns, no teeth have erupted but two sets of teeth are located in the jaw these are primary and permanent teeth. In children aged one to three, about twenty deciduous erupted. By the age of ten, all permeant teeth have erupted. In comparison, young adults have thirty-two permeant teeth, wisdom teeth, and molars between the ages of eighteen and twenty-one. Older adults experience tooth erosion and loss to determine their age. Teeth tend to erupt with a specific pattern but can have some variation.