Baby Tooth Eruption
Teeth begin forming while you are still in the womb. The first primary (or baby) teeth erupt through the gums as early as 3-4 months. These first teeth to erupt are usually the lower central incisors. The upper central incisors will normally follow soon after. All 20 primary teeth have usually appeared by age 3, but the order of their eruption can vary as can the timing.
The transition from all primary teeth to all permanent teeth occurs over many years and usually in two time periods. The first period is from 6 years to 8 years as the incisors are replaced and the first permanent molars come in. The next period begins around 9 to 10 years of age and continues until your child is about 12 years old; during this period the canines and primary molars are replaced.. We use the simplified phrase: lose the first 8 teeth by 8, and the next 12 by 12.