A Quick Guide and Timeline to the Eruption of the Baby Teeth

A baby grows two sets of teeth. The first are a set of twenty baby teeth, also known as the milk teeth or primary teeth. Primary teeth start falling out at as early as 6 years of age, allowing room for thirty-two permanent teeth. The last permanent teeth to erupt are called the wisdom teeth, and may erupt as late as 20 years of age. (Source: wikipedia.org)



Formation of Primary Dentition
Formation of the primary set of teeth actually starts in the embryonic phase. The dental lamina develops in the sixth week of development. Starting with the midline, it spreads backwards. At about ten weeks of embryonic age, ten buds have already formed on each of the upper and lower arches. Ultimately, these twenty buds will develop into a set of twenty teeth in the primary dentition. As mentioned above, the primary dentition consists of twenty teeth, five teeth in each quadrant of the mouth.

Time of Eruption of Primary Teeth
Eruption, or teething, starts at the age of five and a half to six months, and earlier or later in some cases. The primary set is completed in 2 to 3 years. The first teeth to appear are almost invariably the mandibular central incisors. This is so prevalent that a lot of superstition has developed about this in certain societies. Some believe that a child bringing out upper incisors first will turn out to be unlucky for the entire family. The last primary teeth are normally the maxillary second molars.



Anatomy of children teeth (shows eruption and shedding time), vector illustration (for basic medical education, for clinics & Schools)

Anatomy of children teeth (shows eruption and shedding time).


The process of eruption starts at the central lower incisors, and completes two years later at the second molars in the upper jaw. The complete set of primary teeth consists of four identical sets, one in each quadrant of the mouth. Each quadrant has one central incisor, one lateral incisor, one canine, and two molars, making up a total of five in each quadrant. Out of these, the canines are the smaller in width than the others, but have longer roots, and the second molars are the widest.



Morphology of the Primary Teeth
Dental arches formed by the primary dentition are better rounded than those in the permanent dentition. The average overbite may be about 2.5 mm. The incisors are more vertical than in the permanent set. In addition, the primary molars are greater in anterior-posterior dimensions, as compared to the permanent molars, which have comparatively greater thickness.


In early years of child development, the jaws and the alveolar processes grow in size. This leads to development of spaces between the teeth, which creates room for the eruption of the larger permanent teeth, and prevents their crowding within the oral cavity.


“The Mamelons”
Another feature of the primary incisors is the presence of three distinct protuberances on their incisal edges, which are known as the mamelons. These mamelons are absent in the permanent incisor teeth, and gradually wear off with the passage of time, in the primary incisors.


How to Care For Your Baby’s Milk Teeth?
Although the milk teeth are temporary, and are replaced with the permanent teeth, it is still important that parents inculcate the habit of looking after their teeth, into their children. As soon as the first tooth appears, brushing it with a soft toothbrush (with or without a toothpaste) in the morning as well as bedtime is sufficient to prevent tooth decay. Furthermore, the amount and frequency of sugar intake of children should also be controlled.


close-up Baby mouth with two rises teeth

Baby’s mouth with two risen teeth.


What To Do If a Milk Tooth is Prematurely Lost?
Primary teeth serve as placeholders for the permanent teeth. In case a milk tooth is lost prematurely, unless the empty space if filled up with the help of “space maintainers”, the adjacent milk teeth tend to move. This creates spaces between the adjacent teeth, which interferes with the eruption of the permanent teeth, which may erupt at abnormal places.

About Mark C. Marchbanks, D.D.S.

Dr. Mark Marchbanks has practiced dentistry in Arlington Texas since 1983. He enjoys caring for patients young and old. You can find Dr. Marchbanks on
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