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Dental eruption

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Normal tooth eruption

  • Dentition in humans includes a temporary dentition and a permanent dentition;
  • There are 20 temporary or deciduous teeth and they erupt between ± 6 – 10 months of age for the lower jaw (7-12 months of age for the upper jaw) and ± 30 months;
  • There are 28 permanent teeth (32 with wisdom teeth) and they appear between ± 6 and 13 years of age;
  • Girls often have a faster dental development than boys;
  • The eruption of the same tooth on both sides of the dental arch can be delayed. If this delay goes beyond 6 months, talk to your dentist;
  • Primary dentition will be completed between the second and third years of age, and some primary teeth will remain in the mouth until about 12 years of age.
The following tables represent the average age of tooth eruption. A translation of these tables is coming soon. To see a diagram illustrating the eruption and the shedding of primary teeth. Diagram of primary or temporary dental arch.

 

A few facts about dental eruption in humans

Dental eruption is a dynamic and complex biological and physiological process that spans over several years and includes the formation of teeth and their migration in the jaws until they erupt in the mouth in their final functional position in the dental arches.

  • It implies a transition between 2 types of dentition: the temporary or primary dentition and the permanent or definitive dentition.
  • It is closely related to children’ development and craniofacial growth and involves bone and soft (gum) tissues surrounding the teeth, as well as tissue modifications, such as resorption (wear) of the roots of temporary teeth to give way to the permanent teeth.
  • Eruption is a located and symmetrical process, occurring normally at the same time on both sides of the dental arch. This is programmed in time, regulated by the dental follicle and is followed by multiple modifications of tissues, such as resorption.
  • The first stages of development occur during the embryonic stage and end about 20 years later with the eruption of the permanent third molars or wisdom teeth.
  • The process of formation and eruption of teeth is very complex and several theories or hypotheses attempt to explain the mechanisms of eruption without nevertheless having elucidated them completely.
Diagram showing the stages of dental development between 6 and 13 years of age.

Illustration of 3 stages of normal dental development between 6 years of age, age when the first permanent teeth appear, and 12-13 years of age when the eruption of definitive teeth is completed.

 

Chronology of normal tooth eruption


The period or age at which the temporary and permanent teeth appear shows a relatively significant variation which can be related to several factors, such as:

  • Gender: dental eruption occurs in average earlier in girls than in boys, except the upper first molar;
  • Height: literature reports a relationship between a child’s short height and late dental development;
  • Jaws: eruption occurs later in the maxilla than in the mandible;
  • Posterior teeth: the last teeth of each group (third molars, second premolars) are the teeth most affected by delayed eruption;
  • Dentition: late eruptions are less common in the temporary dentition than in the permanent dentition;
  • Population: there are differences in times of eruption of teeth between populations. For instance, European populations show later eruption;
  • Climate: warmer climates seem to favor faster or earlier dental eruption;
  • Socioeconomic conditions: children from a disadvantaged social standing can present a later dental development and eruption;
  • Urbanization level: eruption is faster in urban environments than in the country;
  • Phylogenetic evolution: our modern population presents more eruption problems with wisdom teeth (troisièmes molaires) (third molars) and upper canines. Researchers relate this phenomenon to human evolution and to the lack of jaw development related to changes in food habits of Western populations;
  • Rank in family: eruption occurs later in children that are born last in a family than the older children.
  • The video on the opposite side shows in fast-forward a normal eruption sequence of 32 teeth in humans. The numbers at the bottom represent the eruption age in years.
Examples of significant variations in dental development and eruption.

Examples of significant variations in dental development and eruption. A significant variation in the chronology of the shedding of temporary teeth and the eruption of permanent teeth can exist as shown by these different cases. (A) 16-year-old girl with several primary teeth still in the mouth and still very solid (indicated by *). Most premolars and canines have not yet come out, which should have occurred more than 4 years ago! (B) Another 16-year-old teenager with several temporary teeth in the mouth (*). (C) At the opposite end of the spectrum, this young girl, who is not 10 years old yet, has a dentition of a 12-year-old girl with all her canines and premolars in the mouth.

➡ To see other examples of early and late dental eruption.

Chronological anomalies of eruption

Chronological variations of dental eruption can be early or late eruptions, can affect only one or both dentitions (temporary and permanent) and affect one or several teeth.

Late dental eruption

Late eruptions are less frequent in temporary dentition than in permanent dentition and most late eruptions do not have significant clinical effect. Eruption is considered to be late when it occurs more than 6 months beyond the average age limit of eruption for temporary teeth and more than one year for permanent teeth.

Two situations can explain a delayed eruption:

  • 1- Associated late dental maturation (late eruption); in such case, coordination between dental development and eruption (which is normal) is good but they only occur late.
  • 2- Late eruption in which case dental maturation or formation is normal (late eruption). In such case, dental root formation is normal compared to the child’s age, but a physical obstruction holds back the tooth and prevents it from continuing its normal eruption path. Teeth form normally and can even have completed their formation, but they are blocked, cannot come out and thus become impacted or embedded, which is the ultimate stage of the evolution of late eruption. Dental impaction can be total or partial and can affect all permanent teeth, but certain are more affected (in order of occurrence: wisdom teeth, upper canines, premolars, lower incisors, lower canines and molars).

NOTE : Before talking about late eruption, a differential diagnosis with agenesis (congenital absence of one or several teeth) must be done with a radiological examination.

Early and premature eruption

Early eruption: Dental eruption can also occur earlier than planned. and is thus called early eruption.

  • For temporary teeth, it will most often occur when the tooth bud is positioned superficially under the gingiva. It is also observed in cases of hyperthyroidism and early puberty.
  • Early eruption of the whole permanent dentition is exceptional and can be related to endocrine problems or certain syndromes. Early eruption of a single tooth is more frequent and is usually caused by local etiological factors, such as premature loss of a temporary tooth which is itself most often caused by dental decay.

Premature eruption: It is different from early eruption because it implies immature teeth, always in the bud state, that erupt and can be caused by traumas, tumors, infections, etc.

The cause of early or late eruptions can be various and also be related to:

  • genetic origin,
  • malformations,
  • systemic problems (for instance, a deficiency in vitamin A or D),
  • endocrine disorders,
  • infections,
  • metabolic disorders,
  • local factors (tumors, traumas, position of the bud, etc.).

To see examples of early and late eruption.

 

Dental eruption problems

  • The abnormal eruption path of certain permanent teeth, the lack of space and the premature loss of temporary teeth can cause dental movements;
  • These problems necessitate regular supervision and follow-up to adequately manage the eruption of teeth and minimize harmful consequences;
  • To complete the clinical examination, the best way to detect eruption problems is to take a panoramic radiograph that shows all the forming teeth, their size, their eruption path, the available space, etc.
  • A panoramic radiograph makes it possible to evaluate several potential problems and suggest interventions to minimize the harmful effects on eruption and occlusion;
  • In certain cases, an intervention as simple as extracting certain temporary teeth (serial extractions) can help influence the eruption path of the other teeth and minimize problems.

Panoramic radiograph showing a normal eruption pattern in a 9-year-old young boy. Adequate yearly follow-up will ensure optimal tooth eruption.

A panoramic radiograph makes it possible to evaluate with more details what is not always visible in the mouth

The panoramic radiograph makes it possible to evaluate what is not always visible in the mouth.

 

Visible loss of space and eruption problems on a radiograph of an 11-year-old young boy.

Visible loss of space and eruption problems on a radiograph of an 11-year-old young boy.

 

Loss of space preventing the lower premolars from erupting.

Loss of space preventing the lower premolars from erupting.

Loss of space – Blocked molars

    • The eruption of certain permanent teeth can be blocked by other temporary teeth;
    • These teeth are hard to clean and present a higher risk of cavity;
    • They can cause the loss of temporary teeth and an additional loss of space;
    • This kind of problem can sometimes self-correct; otherwise, an orthodontic intervention is necessary to facilitate the eruption of blocked teeth;
    • The panoramic radiograph is an essential tool to establish a diagnosis and a treatment plan.
Migration of upper molars and loss of space (eruption problem).

Migration of upper molars and loss of space (eruption problem).

Impacted teeth

    • They are teeth that do not come out because they are blocked or have an ectopic eruption path;
    • Often caused by a lack of space or narrow jaws;
    • The premature loss of a temporary tooth can cause space to be lost and prevent the eruption of teeth which will become “impacted”;
    • Several of these problems can be detected early and be intercepted with early supervision.
    • A radiograph is necessary to confirm the presence and position of impacted teeth and determine the best intervention;
    • An impacted tooth can damage other teeth (root wear) and surrounding tissues (bone and gingiva);
    • The upper canines are often impacted. They are among the last teeth to come out, they often do not have enough space and can remain blocked. To learn more on ectopic and impacted canines;
    • The teeth that are most frequently impacted and do not erupt in the mouth are the “wisdom teeth” or third molars.
      Palatally impacted upper canines (indicated by the arrows).

      Palatally impacted upper canines (indicated by the arrows).

      Radiograph and picture showing the position of the canines in the palate (indicated by the arrows).

      Radiograph and picture showing the position of the canines in the palate (indicated by the arrows).

Impacted premolar (arrow) heading under another premolar and causing root wear (resorption). The early extraction of the temporary molar (T) could have helped prevent this condition. Impacted premolar (arrow) heading under another premolar and causing wear of the root (resorption). The early extraction of the temporary molar (T) could have helped prevent this condition.

Ectopic dental eruption

  • It refers to a permanent tooth that erupts in an abnormal position;
  • Just like impacted teeth, ectopic teeth can damage adjacent teeth and supporting tissues (bone and gum).
Lack of space, dental crowding, ectopic eruption of premolars (in the palate) and a canine in a 14-year-old boy.

Lack of space, dental crowding, ectopic eruption of premolars (in the palate) and a canine in a 14-year-old boy.

 

Lower left lateral incisor tipped backward in an ectopic position and preventing the normal eruption of the other teeth located below.

Canines frequently present eruption problems. To learn more on ectopic and impacted canines.


réf. : – E. Moulis et al. Anomalies de l’éruption, encyclopédie médico-chirurgicale, 2002 
  – Univ. Paul Sabattier – odontologie/pedagogie/cours/eruption/

© Original publication www.orthoLemay.com, November 28, 2009.

 

 

 

 

Comments and/or questions (24)

  1. Nikitha says:

    my age is 23 at present my age teeth is growing pain is sevier pls suggest on this

  2. nancy says:

    Hi, my 7 year old daughter had a slight fall when she was 3 years old causing her front upper baby tooths to be black & not growing. Now, she has erupting permanent upper tooth which can clearly be seen on her gum. The doctor advised us to wait for 3-6months to let the baby tooth to loose & fall out on its own. I don’t think it will fall out. What should we do? The erupting permanent tooth is growing bigger. The doctor also advised us for extraction which I think going to be very painful as he needs to really pull the baby tooth out. Please advise. Thank you.

    • Dr Jules says:

      If the permanent incisors are just under the baby teeth, there is not much root left on these deciduous teeth and they can easily be extracted. It may be necessary to extract more that the 2 central incisors to make room for the bigger permanent teeth but the incisor roots are conical and not very difficult to extract either.

  3. Ami says:

    My daughter is currently 13 months old, but doesn’t have any teeth yet should I be worried?
    Are there any permanent effects on late sprouting teeth?

  4. Sarah McConnell says:

    My 12month old son started showing signs of central bottom left lower tooth 3-4 weeks ago. In the past 2 weeks it has only erupted half way and seems to be “stalled.” How long do teeth usually take to come through the surface? It also seems to have quite a counter-clockwise angle to it, but from what I’ve read this doesn’t really indicate a problem.

    • Dr Jules says:

      It can take weeks or months for a tooth to erupt. Even if is was rotated or inclined, there is nothing that can be done at that age.

  5. Majoni says:

    Hi, my daughter is 6 and a half year old she got her 1st molar. But till now her front tooth is not shaking. She complains of sensitivity while chewing and touching.Also I can see a small part of 1st molar has a small part of gum attached on top of it. Are these normal or need to see a doctor?

    • Dr Jules says:

      It is normal to have partial gum tissue covering a tooth until it is completely erupted. This should go away with time (weeks).

  6. Murtaza says:

    My daughter is just 6 years old.Lower temorary central teeth are loosen but still are present while 1st permanent tooth has been erupted on back of these teeth.Is it normal?Or temproray teeth may be removed by force.

    • Dr Jules says:

      Lower permanent incisors usually erupt on the lingual (tongue) side but may stay on that side if there is lack of anterior space in the dental arch, which is very common. The deciduous (baby)teeth will eventually fall out or you can work them loose if they are loose enough.

      Consult an orthodontist in the next year to have a better idea of what is going on with your daughter’s dentition and dental development.

      ➡ To find out why a first orthodontic consultation is indicated when a child is 7 years old.

  7. Maureen says:

    My Son just turned 6 this month, but he lost his first baby tooth (the front tooth) when he was 5 and the permanent tooth erupted within weeks. The second one came loose but fell out when his brother accidentally hit his mouth. It’s been over a month, and it hasn’t erupted. Do I need to be worried? Is it normal?

    • Dr Jules says:

      A delay of a few weeks is not unusual but consult your dentist if the new incisor is not visible after a few months.

  8. Yvette says:

    One incisor is not eruptiong

    Hi
    My boy had a fall when he was 4 and his left central incisor fell out. He is 7 now. His baby right central incisor dropped out a few months back and the permant central right incisor has grown out. It has been a few months and there is no sign of the left permanent incisor growing out. We had previously taken an x-ray and the adult tooth has been formed. There is also nothing blocking the path of its growth. Is it normal that the 2 central incisors are not growing out at the same time? Do we need to be concerned?

    • Dr Jules says:

      Incisors rarely grow exactly at the same rate or at the same time. However, if there is no obstruction in the path of eruption and one of the incisors is lagging behind and doesn’t erupt, that tooth may be fused to the bone (ankylosis) and may need some “help” to further erupt. Consult your dentist if that seems to be the case (delayed eruption) so that he can evaluate the situation and make the appropriate recommendations.

  9. Andreab says:

    my son is 15 and is still missing several adult teeth. He has his front four top and bottom teeth. The dentist says they’re are up there based on the x-rays – should I be concerned? should I take him to a specialist?

    • Dr Jules says:

      Having only the 4 incisors erupted at age 15 is very delayed and unusual. The other permanent teeth may be visible on the radiograph but an evaluation must be made to determine if they are developing normally (they are obviously delayed in their formation), if they have enough space and the right direction to erupt. etc.

      Unless your general dentist is very confident that he has the experience and expertise to manage such a case (diagnosis and treatment), I would not hesitate to obtain a second opinion form a certified specialist in orthodontics (orthodontist)

  10. mar says:

    Hi, my son is 6 and a half, he lost his top front teeth, one was 7 months ago and the other 5 months ago. My worry is there is no sign of them coming though. Is it normal for them to take so long to grow in?

    • Dr Jules says:

      It is hard to say, but after a delay of 6 months, this may be an indication that there something preventing normal tooth eruption. It may be simply a lack of space, an extra tooth (mesiodens) blocking the teeth or something else. Start by consulting your general dentist so that he/she can evaluate the situation and refer you to a certified specialist in orthodontics (orthodontist) if necessary.

  11. Karina says:

    My son is 14 and his 1st and 2nd molar on the top right side have yet to erupt. His orthodontist recommends having a procedure to open the gum. Does this need to be done or can we wait for the molars to erupt on their own?

    • Dr Jules says:

      The first molar normally erupts at around 6-7 years of age and the second molar at around 12 years of age so he is years behind schedule! This requires a radiographic investigation to try to explain the reason for that significant delay… but you probably already had this done. Depending on the cause of the delay, it may indeed be indicated to try to “stimulate” or accelerate the eruption of these molars by removing the gum tissue covering them. If these molars were to erupt on their own, they would have done so years ago so helping them is problably the right thing to do at this point.

  12. Shay says:

    My 12-month-old daughter has her two front upper and lower teeth but also, only on one side, has her top and bottom lateral incisors and her first molar. Should I be concerned that she has 3 new teeth in the last 2 months that have only come in on the left side of her mouth?

  13. Sampurna says:

    My sons lower central incisors were fallen and replaced by new ones. Now.. his upper central incisor are getting loose and no eruption yet.. but ..lower lateral incisor has come out. How does it possible before falling upper central incisor? Should we take out lower lateral incisor first?? Bcoz there is new teeth coming out.
    He will b 7 in 13 december.

  14. Dr Jules says:

    There are a lot of individual variations in the sequence and timing of dental eruption. Even if there was something abnormal, there is nothing you could do at this stage. Consult a dentist within the next year and he/she will evaluate your daughter’s dentition and reassure you.

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