Also know as deciduous teeth, or primary teeth. Usually start to erupt into the child’s mouth around 4 to 6 months with the last baby teeth erupting around two years of age. There are only 20 baby teeth. There are four molars, two canines and four incisors per jaw. They are identified by letters starting with the upper right second primary molar (the most back molar). This is tooth letter A the sequence continues around the upper jaw ending with J which is the upper left second molar, then restarting with the lower left second molar which is K continuing in sequence around the lower jaw ending with T the lower right second molar.