A general rule of thumb is that for every 6 months of life, approximately 4 teeth will erupt.
Girls generally precede boys in tooth eruption.
Lower teeth usually erupt before upper teeth.
Teeth in both jaws usually erupt in pairs -- one on the right and one on the left.
Primary teeth are smaller in size and whiter in color than the permanent teeth that will follow.
By the time a child is 2 to 3 years of age, all primary teeth should have erupted.
Shortly after age 4, the jaw and facial bones of the child begin to grow, creating spaces between the primary teeth. This is a perfectly natural growth process that provides the necessary space for the larger permanent teeth to emerge. Between the ages of 6 and 12, a mixture of both primary teeth and permanent teeth reside in the mouth.