By the time an infant is born baby teeth, more exactly known as deciduous teeth or primary teeth, are fully formed. Deciduous teeth usually remain hidden under the gums until they begin to erupt between 5 months and 8 months of age. This process is called teething.
Eight incisors (four front teeth on both the upper and lower jaw), eight molars (larger teeth in the back of the mouth) and four canines (located in the front of the jaw behind the incisors) are twenty primary teeth. Normally they erupt by the time a child is 3 years old. Eruption of the top teeth generally follows eruption of the lower teeth. Eruption times for girls are commonly earlier than those for boys.
The American Dental Association (ADA) established such schedule for the top primary teeth:
- 8 months to 12 months - central incisor;
- 9 months to 13 months - lateral incisor;
- 16 months to 22 months - canine (cuspid);
- 13 months to 19 months - first molar;
- 25 months to 33 months - second molar.
The bottom primary teeth erupt as follows:
- 6 months to 10 months - central incisor;
- 10 months to 16 months - lateral incisor;
- 17 months to 23 months - canine (cuspid);
- 14 months to 18 months - first molar;
- 21 months to 31 months - second molar.
Primary teeth are very important for children. They help with biting and chewing, and are crucial to a child’s ability to speak. At last, deciduous teeth serve as a guide for permanent teeth. That's why primary teeth usually have more space between them to allow permanent teeth more room to appear.
Finally, a child’s primary teeth begin to fall out. The front middle teeth as a rule fall out when a child is 6. Molars in the back are shed between the ages of 10 and 12. At the age of 13 a child usually has permanent teeth.
In the meantime, permanent incisors and canines replace primary incisors and canines. Permanent first and second premolars (bicuspids) replace the primary first and second molars. The permanent molars which grow towards the back of the mouth do not replace baby teeth. That is why there are more teeth in permanent dentition. In such a way a total of 32 permanent teeth replace the original 20 primary teeth.