Tooth Formation

Objectives: Participants will...

  • Learn about the development of the primary dentition.
  • Be able to describe to new mother the pattern of eruption of primary teeth.
  • Know what to suggest to new mothers to alleviate baby’s teething symptoms.

At birth, all twenty primary teeth are already formed in the baby’s jaws, hidden in bone and soft tissue until time to erupt in the mouth. There are also the beginning buds of some permanent teeth.

There are conflicting conclusions concerning the relationship between the eruption of the primary dentition and the accompanying local and systemic disturbances. Some physicians have been reluctant to admit that teething causes disturbances, fearing that mothers will attribute to teething serious (respiratory or gastrointestinal) infections associated with high fever. Teething is not associated with a high fever, but with a low grade fever of short duration. Parents should be counseled to see their pediatrician if fever persists more than 24 hours, or is a high fever, to determine the cause and appropriate action.

Teething is a natural process. Before a baby’s teeth come into their mouth they will begin to “mouth” many different objects. It is important to remove any objects that may be dangerous to them, or small enough for a baby to swallow. When baby’s teeth are ready to erupt, the gingiva may become swollen and tender. Baby may become irritable and restless and may have increased drooling. Rubbing baby’s gums with a clean finger or giving baby something like a teething ring to bite on may be soothing. A very cold teething ring from the refrigerator (not freezer) or a cold washcloth work best. The physician or dentist may prescribe something, e.g. Orabase, Baby Orajel or Zilactin Baby, when baby is extremely uncomfortable. These products are sometimes helpful. However, we advise avoiding commercial preparations as they are short acting, diluted quickly by saliva and not always tolerated well by some infants. Teething symptoms usually vanish when the tooth erupts.

Eruption of primary teeth starts at about 6 months of age and is usually completed by age three. Approximately every six months four teeth erupt. It follows a specific pattern of centrals, laterals, first molars, canines and second molars with the mandibular(lower) teeth coming in before the maxillary(upper) teeth.

Development of the primary dentition

Eruption Age in Months
Tooth Initial Calcification
(wks. in utero)
10(8-12) Maxillary Central 14
11(9-13) Lateral 16
19(16-22) Canine 17
16(13-19) First Molar 15.5
29(25-33) Second Molar 19
8(6-10) Central 14
13(10-16) Lateral 16
20(17-23) Canine 17
16(14-18) First molar 15.5
27(23-31) Second molar 18