6 years. The front middle teeth (incisors) are the first ones to go. Most kids loose their back teeth (molars) between 10-12 years of age.
5 years. Usually the first teeth are lost between five and six years of age. There is a lot of variability.
6 years. Children lose their first baby teeth around age 6 years when the permanent teeth start coming in. They will get a total of 28 teeth (not counting any wisdom teeth). In the teen years, some kids have 2-4 teeth pulled before getting orthodontic braces. Years later, adults lose teeth through accidents, tooth decay, etc. . . The average number of remaining teeth at age 50-64 is 22-23 teeth.