Baby Teeth / Tooth eruption & loss timetables.
What are they?
During their lifetime, a person will have two sets of teeth. The first set is typically referred to as the baby or milk teeth. More formally, they are termed the primary or deciduous dentition.
Baby teeth usually begin to erupt (come in) at around age 6 months. And in most cases, by age 12 years all of them have exfoliated (fallen out) and been replaced by the person's "permanent" teeth. (See the tables below for more precise ages.)
Types and numbers.
As a set, the baby teeth are composed of a total of 20 individual teeth. They are divided equally (10 each) between the upper and lower arches (jaws).
- 8 Incisors - A child's center two front teeth are their central incisors. The teeth positioned just to their sides are their lateral incisors.
- 4 Cuspids - These teeth, also termed canines or eyeteeth, lie next in line behind the incisors.
- 8 Molars - The first and then second molars are positioned furthest toward the rear of the mouth.
|Test yourself on the subject of primary tooth identification by taking one of our quizzes.|
When do baby teeth come in? (Tooth eruption.)
Although a child's deciduous teeth begin to calcify in utero (before the child is delivered), they typically don't begin to make an appearance inside their mouth until about 6 months of age. Usually by age 2 to 2 1/2 years all have erupted and are in place.
|Primary tooth eruption time frames.|
|Tooth type||Lower arch||Upper arch|
|Central incisors||6 1/2 months||7 1/2 months|
|Lateral incisors||7 months||8 months|
|Cuspids||16 to 20 months||16 to 20 months|
|First molars||12 to 16 months||12 to 16 months|
|Second molars||20 to 30 months||20 to 20 months|
Eruption times can vary.
The precise age of eruption often varies. Some children get their teeth relatively early, others later. These variances often correlate with family histories, in the sense that what a child experiences is similar to that which took place with one of their siblings or parents.
When does a child loose their primary teeth? (Tooth exfoliation.)
Baby teeth exfoliate (fall out on their own) as their permanent replacements come in. The table below gives the typical age range for this event for each type of tooth, as well as the type of permanent tooth that replaces it.
|Primary tooth exfoliation (shedding) time frames.|
|Tooth type||Lower arch||Upper arch||Permanent replacement tooth.|
|Central incisors||6 - 7 years||6 - 7 years||Central incisor|
|Lateral incisors||7 - 8 years||7 - 8 years||Lateral incisor|
|Cuspids||9 to 12 years||10 to 12 years||Canine|
|First molars||9 to 11 years||9 to 11 years||First premolar|
|Second molars||10 to 12 years||10 to 12 years||Second premolar|
Exfoliation ages can vary.
Just as with tooth eruption, the precise age at which a deciduous tooth is lost can vary, often by months or years (see the table above). When one does, it can be expected that the corresponding tooth on the other side will come out during a similar time frame.
A permanent tooth must reach a certain point in its development before it can erupt. Eruption begins once the tooth's crown portion (the non-root part) has completed calcification. But typically 2/3rds of its root must form before it will emerge from the jawbone and into the mouth (a tooth's root may not finish completely forming until some years after its eruption).
That means if the natural progress of a child's dental development is comparatively slow, it will delay the age (by months, possibly years) at which their primary teeth are lost.
Why do baby teeth come out so easily?
It may seem strange that a child's deciduous teeth are anchored so firmly, for so long, and then, right on schedule, seem to just fall out.
There's an easy explanation for this. Despite the way that exfoliated baby teeth look, for most of their lifespan they do have a substantial root complex. But as their replacement comes in (the permanent tooth underneath), its presence causes their root to resorb (dissolve away).
As our graphic illustrates, as the permanent tooth moves through the jawbone ever closer to the surface, the root of the baby tooth above becomes shorter and shorter. Finally a point is reached where it's no longer substantial enough to keep it anchored and it is easily dislodged.
What should you do if your child's baby teeth don't come in or fall out on schedule?
If your child's primary teeth don't come in or aren't lost on schedule, it will take an evaluation by your dentist to determine what type of attention, if any, is required. This examination will likely require taking one or more x-rays.
Irregularities with eruption and exfoliation ages can be associated with the following issues:
Teeth that never form, of course, won't erupt. This deficiency may involve just one, only a few, or possibly several tooth locations.
In the case of missing permanent teeth, the primary tooth they were intended to replace will not fall out as expected. Retained deciduous teeth won't last a lifetime and a plan for their eventual replacement should to be made.
A number of medical conditions are known to be associated with the premature or delayed loss of baby teeth.
Premature loss - Fibrous dysplasia, Juvenile diabetes, Histiocytosis, Cyclic neutropenia, Hypophosphatasia, Chediak-higashi syndrome, Vitamin D resistant Rickets.
Delayed loss - Cleidocranial dysplasia, Sclerosteosis, Gardner's syndrome, Vitamin D resistant Rickets, Downs syndrome, Hypopituitarism, Hypothyroidism.
Immediate action may not be required but a general plan for managing the child's dental situation should be made.
Tooth crowding or misalignment.
Abnormalities with baby tooth exfoliation can be due to poor tooth alignment or orientation. In these cases, the evaluating dentist can explain what treatment can be used (either now or in stages as the child develops) to help to make room for and/or guide the permanent teeth into place.
Crowded baby teeth may call for the use of "serial extractions." This is a process where selected baby teeth are removed a little bit early so to facilitate the eruption of the permanent teeth underneath.
Some severely misoriented permanent teeth may be impacted (unable to erupt). If so, their corresponding baby tooth will be retained. It may need to be extracted and the impacted tooth surgically exposed so some type of orthodontic appliance can be used to guide it into its proper place.
The presence of supernumery (extra) permanent teeth may block or otherwise prevent neighboring teeth from coming into place. This can result in retained baby teeth.
The solution is typically to remove the supernumery tooth and then, if needed, orthodontically guide the neighboring teeth into place.
Sometimes what a parent interprets as being a problem, while not exactly ordinary, is something that can be expected to either resolve on its own or require only minor dental treatment.
These types of situations might include permanent teeth that erupt slightly off target, resulting in baby teeth that aren't loosened enough to fall out on their own. Or eruption complications associated with fused baby teeth or dense overlying gum tissue.