Tooth eruption

Last updated
Tooth eruption
Gray1001.png
The removed bone reveals permanent teeth below the roots of primary teeth.
Biological system System
ActionInvoluntary
Stimuli Biological development / ageing
Outcome
  • To enable use of teeth (primary)
  • To replace damaged and missing teeth (mixed and permanent)
Frequency3 stages per lifetime

Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligament plays an important role in tooth eruption. The first human teeth to appear, the deciduous (primary) teeth (also known as baby or milk teeth), erupt into the mouth from around 6 months until 2 years of age, in a process known as "teething". These teeth are the only ones in the mouth until a person is about 6 years old creating the primary dentition stage. At that time, the first permanent tooth erupts and begins a time in which there is a combination of primary and permanent teeth, known as the mixed dentition stage, which lasts until the last primary tooth is lost. Then, the remaining permanent teeth erupt into the mouth during the permanent dentition stage.

Contents

Theories

Although researchers agree that tooth eruption is a complex process, there is little agreement on the identity of the mechanism that controls eruption. [1] There have been many theories over time that have been eventually disproven. [2] According to Growth Displacement Theory, [3] the tooth is pushed upward into the mouth by the growth of the tooth's root in opposite direction. Continued Bone Formation Theory advocated that a tooth is pushed upward by the growth of the bone around the tooth. In addition, some believed teeth were pushed upward by vascular pressure or by an anatomic feature called the cushioned hammock. The cushioned hammock theory, first proposed by Harry Sicher, was taught widely from the 1930s to the 1950s. This theory postulated that a ligament below a tooth, which Sicher observed under a microscope on a histologic slide, was responsible for eruption. Later, the "ligament" Sicher observed was determined to be merely an artifact created in the process of preparing the slide. [4]

The most widely held current theory is that while several forces might be involved in eruption, the periodontal ligament provides the main impetus for the process. Theorists hypothesize that the periodontal ligament promotes eruption through the shrinking and cross-linking of their collagen fibers and the contraction of their fibroblasts. [5]

There is good evidence from experimental animals that a traction force is unlikely to be involved in tooth eruption: Animals treated with lathyrogens that interfere with collagen cross-link formation showed similar eruption rates to control animals, provided occlusal forces were removed.

Inherent in most of the theories outlined above is the idea that a force is generated in the periodontal ligament beneath unerupted teeth, and that this force physically drives teeth out through the bone. This idea may have been superseded by a further recent theory. This new theory proposes firstly that areas of tension and compression are generated in the soft tissues surrounding unerupted teeth by the distribution of bite forces through the jaws. These patterns of tension and compression, are further proposed to result in patterns of bone resorption and deposition that lift the tooth into the mouth. [6] This theory is based on Wolff's law, which is the long established idea that bone changes shape in accordance with the forces applied. [7] Significantly, a recent finite element analysis study, analysing the distribution of force through the jaw of an 8-year-old child, observed overall compression in the soft tissues above, and tension in the soft tissues below, unerupted teeth. [6] Because bone resorbs when compressed, and forms under tension, this finite element analysis strongly supports the new theory. [6] Further work is required, however, to confirm this new theory experimentally.

Timeline

The deciduous mandibular central incisors, shown here in the mouth of a seven-month-old female infant, are the first teeth to erupt. Baby teeth in human infant.jpg
The deciduous mandibular central incisors, shown here in the mouth of a seven-month-old female infant, are the first teeth to erupt.
Bottom teeth of a seven-year-old, showing primary teeth (left), a lost primary tooth (middle), and a fully erupted permanent tooth (right) ToothLost-2917.jpg
Bottom teeth of a seven-year-old, showing primary teeth (left), a lost primary tooth (middle), and a fully erupted permanent tooth (right)

Although tooth eruption occurs at different times for different people, a general eruption timeline exists. The tooth buds of baby teeth start to develop around 6 weeks of pregnancy. Adult teeth buds start forming around 4 months of pregnancy. The entire tooth will start to form from the crown down to the root. [8] Typically, humans have 20 primary teeth and 32 permanent teeth. [9] The dentition goes through three stages. [10] The first, known as primary dentition stage, occurs when only primary teeth are visible. Once the first permanent tooth erupts into the mouth, the teeth that are visible are in the mixed (or transitional) dentition stage. After the last primary tooth is shed or exfoliates out of the mouth, the teeth are in the permanent dentition stage. Each patient should be assigned a dentition period to allow for effective dental treatment. [10]

Signs and symptoms of tooth eruption

There are several signs and symptoms associated with the eruption of primary teeth. It is a process that begins with the eruption of the mandibular central incisors at the age of 6 months. A common symptom among young children is a mild rise of temperature, however this is not necessarily classified as a fever. General symptoms during primary tooth eruption include; irritability and drooling being the most common, followed by a decreased appetite, sleeping problems, rhinorrhea, fever, diarrhea, rash and vomiting. Local signs included inflammation of the gums and Gingival reddening (Hyperemia) most commonly presenting in posterior teeth. A study shows that 70.5% of children between 0–36 months showed signs and symptoms of tooth eruption whether it being a fever, Gingival irrational and/or drooling. [11]

Primary dentition stage

Primary dentition stage starts on the arrival of the mandibular central incisors, typically from around six months, and lasts until the first permanent molars appear in the mouth, usually at six years. [12] There are 20 primary teeth and they typically erupt in the following order: (1) central incisor, (2) lateral incisor, (3) first molar, (4) canine, and (5) second molar. [13] As a general rule, four teeth erupt for every six months of life, mandibular teeth erupt before maxillary teeth, and teeth erupt sooner in females than males. [14] During primary dentition, the tooth buds of permanent teeth develop inferior to the primary teeth, close to the palate or tongue.

Mixed dentition stage

Mixed dentition stage starts when the first permanent tooth appears in the mouth, usually at five or six years with the first permanent molar, and lasts until the last primary tooth is lost, usually at ten, eleven, or twelve years. [15] There are 32 permanent teeth and those of the maxillae (on the top) erupt in a different order from permanent mandibular (on the bottom) teeth. Maxillary teeth typically erupt in the following order: (1) first molar (2) central incisor, (3) lateral incisor, (4) first premolar, (5) second premolar, (6) canine, (7) second molar, and (8) third molar. Mandibular teeth typically erupt in the following order: (1) first molar (2) central incisor, (3) lateral incisor, (4) canine, (5) first premolar, (6) second premolar, (7) second molar, and (8) third molar. [16] While this is the most common eruption order, variation is common.

Since there are no premolars in the primary dentition, the primary molars are replaced by permanent premolars. [17] [18] If any primary teeth are shed or lost before permanent teeth are ready to replace them, some posterior teeth may drift forward and cause space to be lost in the mouth. [19] [20] This may cause crowding and/or misplacement once the permanent teeth erupt, which is usually referred to as malocclusion. Orthodontics may be required in such circumstances for an individual to achieve a functioning and aesthetic dentition.

Permanent dentition stage

The permanent dentition begins when the last primary tooth is lost, usually at 11 to 12 years, and lasts for the rest of a person's life or until all of the teeth are lost (edentulism). After the adult tooth forms in the bone, it will push through under the baby tooth. The adult tooth will dissolve the baby tooth's root, making the baby tooth loose until it falls out. [8] During this stage, permanent third molars (also called "wisdom teeth") are frequently extracted because of decay, pain or impactions. The main reasons for tooth loss are decay or periodontal disease. [21]

Active vs. Passive eruption

Active eruption

Active eruption is known as eruption of teeth into the mouth towards the occlusal plane. This is a natural path of eruption of all the teeth as they emerge from gingiva and continue erupting until they make contact with the opposing tooth.

Passive eruption

Passive eruption is known as movement of the gingiva apically or away from the crown of the tooth to the level of Cementoenamel junction (CEJ) after the tooth has erupted completely. Problems in gingival tissue migrating apically can give rise to what is known as altered or delayed passive eruption. [22] In this phenomenon, the gingival tissues fail to move apically and thus lead to shorter clinical crowns with more square-shaped teeth and appearance of what is known as gummy smile.

Coslet classification

Coslet et al. [23] classified delayed passive eruption into two types which related the bone crest of a tooth to the Mucogingival junction (MGJ) of that tooth. These two groups were further divided based on the position of the alveolar bone crest to the cementoenamel junction.

TypeOsseous crest levelAttached gingival levelGingival margin levelTreatment
Type 1aApical to CEJAdequateIncisal to CEJGingivectomy
Type 1bAt CEJAdequateIncisal to CEJGingivectomy and osseous surgery
Type 2aApical to CEJInadequateIncisal to CEJApically positioned flap
Type 2bAt CEJInadequateIncisal to CEJApically positioned flap and osseous surgery

Abnormalities

Abnormalities in tooth eruption (timing and sequence) are often caused by genetics and may result in malocclusion. In severe cases, such as in Down syndrome, the eruption may be delayed by several years and some teeth may never erupt. [24] [25] [26] [27]

Primary failure of eruption

Primary failure of eruption (PFE) is a rare disease in which tooth eruption does not occur despite space in the arch for eruption.

Non-eruption of non-ankylosed teeth occurs due to an eruption mechanism that has failed leading to a posterior unilateral/bilateral open bite. [28] Infra occlusion is the primary hallmark of PFE. Primary teeth are most commonly affected and normally all teeth distal to the most mesially affected tooth will show characteristics of this disease. PFE can be treated by orthodontic treatment, however this is dependent on the patient's age, preference and clinical situation. [28]

Cleidocranial Dysplasia

Cleidocranial Dysplasia (CCD) is a disorder characterised by the identification of a heterozygous pathogenic variant in RUNX2 (CBFA1) and/or various clinical presentations and radiographs. There is a wide range of clinical presentations found in patients with CCD, including patients with a classical presentation of the disorder to patients who have isolated dental anomalies. These will often affect the mechanisms of tooth eruption and result in problems within primary and secondary dentition. Studies have shown that up to 94% of persons with CCD spectrum disorder have dental findings including supernumerary teeth and eruption failure of permanent teeth. The presence of a second permanent molar within primary dentition is the most common at 80% along with wide spacing in the lower incisor area, supernumerary tooth germs (705) and parallel-sided ascending rami. Individuals with a CCD spectrum disorder are also more likely to have an underbite and to have cysts in their gums that usually form around extra teeth. Dental procedures can be carried out for the retention of deciduous teeth and non-eruption of permanent teeth. A combination of surgical and orthodontic work can also be considered for actively erupting teeth. [29]

Cleft lip

Reports have noted that there is late tooth eruption in cleft lip patients when contrasted with non cleft lip patients. The duration of delay is around 0.2 to 0.9 years, with an average of 0.56 years when all types of clefts were accounted for. The lateral incisor on the cleft side was typically the most delayed. The type of cleft and the severity of the condition did not affect the duration of tooth eruption. Overall, teeth which were located closer to the cleft lip took a longer time to erupt compared to teeth which were further away. [30]

See also

Related Research Articles

<span class="mw-page-title-main">Human tooth</span> Calcified whitish structure in humans mouths used to break down food

Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.

<span class="mw-page-title-main">Dentition</span> Development and arrangement of teeth

Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology of the teeth of an animal.

<span class="mw-page-title-main">Incisor</span> Front teeth of most mammals

Incisors are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight. Opossums have 18, whereas armadillos have none.

<span class="mw-page-title-main">Wisdom tooth</span> Large tooth at the back of the human mouth

A third molar, commonly called wisdom tooth, is one of the three molars per quadrant of the human dentition. It is the most posterior of the three. The age at which wisdom teeth come through (erupt) is variable, but this generally occurs between late teens and early twenties. Most adults have four wisdom teeth, one in each of the four quadrants, but it is possible to have none, fewer, or more, in which case the extras are called supernumerary teeth. Wisdom teeth may get stuck (impacted) against other teeth if there is not enough space for them to come through normally. Impacted wisdom teeth are still sometimes removed for orthodontic treatment, believing that they move the other teeth and cause crowding, though this is not held anymore as true.

Hypodontia is defined as the developmental absence of one or more teeth excluding the third molars. It is one of the most common dental anomalies, and can have a negative impact on function, and also appearance. It rarely occurs in primary teeth and the most commonly affected are the adult second premolars and the upper lateral incisors. It usually occurs as part of a syndrome that involves other abnormalities and requires multidisciplinary treatment.

<span class="mw-page-title-main">Periodontal fiber</span> Group of specialized connective tissue fibers

The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum on one side and onto alveolar bone on the other.

<span class="mw-page-title-main">Human tooth development</span> Process by which teeth form

Tooth development or odontogenesis is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. For human teeth to have a healthy oral environment, all parts of the tooth must develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth week of prenatal development, and permanent teeth begin to form in the twentieth week. If teeth do not start to develop at or near these times, they will not develop at all, resulting in hypodontia or anodontia.

<span class="mw-page-title-main">Malocclusion</span> Medical condition

In orthodontics, a malocclusion is a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The English-language term dates from 1864; Edward Angle (1855-1930), the "father of modern orthodontics", popularised it. The word "malocclusion" derives from occlusion, and refers to the manner in which opposing teeth meet.

<span class="mw-page-title-main">Dental follicle</span>

The dental follicle, also known as dental sac, is made up of mesenchymal cells and fibres surrounding the enamel organ and dental papilla of a developing tooth. It is a vascular fibrous sac containing the developing tooth and its odontogenic organ. The dental follicle (DF) differentiates into the periodontal ligament. In addition, it may be the precursor of other cells of the periodontium, including osteoblasts, cementoblasts and fibroblasts. They develop into the alveolar bone, the cementum with Sharpey's fibers and the periodontal ligament fibers respectively. Similar to dental papilla, the dental follicle provides nutrition to the enamel organ and dental papilla and also have an extremely rich blood supply.

<span class="mw-page-title-main">Permanent teeth</span> Second set of teeth in diphyodont mammals

Permanent teeth or adult teeth are the second set of teeth formed in diphyodont mammals. In humans and old world simians, there are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.

<span class="mw-page-title-main">Veterinary dentistry</span> Branch of veterinary medicine

Veterinary dentistry is the field of dentistry applied to the care of animals. It is the art and science of prevention, diagnosis, and treatment of conditions, diseases, and disorders of the oral cavity, the maxillofacial region, and its associated structures as it relates to animals.

Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth. This disturbance is more likely to affect the maxillary incisors and occurs in permanent dentition. Although this may seem more of an aesthetics issue, an impacted maxillary incisor will cause issues related to occlusion, phonetics, mastication, and psychology on young patients.

<span class="mw-page-title-main">Gingival sulcus</span> Space between tooth and gums

The gingival sulcus is an area of potential space between a tooth and the surrounding gingival tissue and is lined by sulcular epithelium. The depth of the sulcus is bounded by two entities: apically by the gingival fibers of the connective tissue attachment and coronally by the free gingival margin. A healthy sulcular depth is three millimeters or less, which is readily self-cleansable with a properly used toothbrush or the supplemental use of other oral hygiene aids.

Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. Tooth formation begins before birth, and the teeth's eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.

Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest.

Dental pertains to the teeth, including dentistry. Topics related to the dentistry, the human mouth and teeth include:

Serial extraction is the planned extraction of certain deciduous teeth and specific permanent teeth in an orderly sequence and predetermined pattern to guide the erupting permanent teeth into a more favorable position.

Tooth ankylosis is the pathological fusion between alveolar bone and the cementum of teeth, which is a rare phenomenon in the deciduous dentition and even more uncommon in permanent teeth. Ankylosis occurs when partial root resorption is followed by repair with either cementum or dentine that unites the tooth root with the alveolar bone, usually after trauma. However, root resorption does not necessarily lead to tooth ankylosis and the causes of tooth ankylosis remain uncertain to a large extent. However, it is evident that the incident rate of ankylosis in deciduous teeth is much higher than that of permanent teeth.

Failure of eruption of teeth happens when a single or multiple teeth fail to erupt in the mouth. This can happen due to many reasons which may include obstruction from primary teeth, bone surrounding the unerupted tooth or other mechanical factors. The two types of failure of eruption are primary failure of eruption and mechanical failure of eruption. Primary failure of eruption has been known to be associated with Parathyroid hormone 1 receptor mutation.

<span class="mw-page-title-main">Alveolar cleft grafting</span>

Alveolar cleft grafting is a surgical procedure, used to repair the defect in the upper jaw that is associated with cleft lip and palate, where the bone defect is filled with bone or bone substitute, and any holes between the mouth and the nose are closed.

References

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  2. ↑ Harris, Edward F. Craniofacial Growth and Development. In the section titled "Tooth Eruption." 2002. pp. 1–3.
  3. ↑ "Tooth Development and Eruption". Archived from the original on 25 January 2013. Retrieved 16 June 2012.
  4. ↑ Harris, Edward F. Craniofacial Growth and Development. In the section titled "Tooth Eruption." 2002. p. 3.
  5. ↑ Harris, Edward F. Craniofacial Growth and Development. In the section titled "Tooth Eruption." 2002. p. 5.
  6. 1 2 3 Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans (2013-03-15). "Tooth Eruption Results from Bone Remodelling Driven by Bite Forces Sensed by Soft Tissue Dental Follicles: A Finite Element Analysis". PLOS ONE. 8 (3): e58803. Bibcode:2013PLoSO...858803S. doi: 10.1371/journal.pone.0058803 . ISSN   1932-6203. PMC   3598949 . PMID   23554928.
  7. ↑ Frost, Harold M. (February 2004). "A 2003 update of bone physiology and Wolff's Law for clinicians". The Angle Orthodontist. 74 (1): 3–15. PMID   15038485.
  8. 1 2 Graves, Elizabeth (15 August 2022). "A Guide to Teeth Erupting for Baby and Adult Teeth". Take Home Smile.
  9. ↑ The American Dental Association, Tooth Eruption Charts at http://www.mouthhealthy.org/en/az-topics/e/eruption-charts.aspx
  10. 1 2 Illustrated Dental Embryology, Histology, and Anatomy, Bath-Balogh and Fehrenbach, Elsevier, 2011, page 191-192
  11. ↑ Massignan, Carla; Cardoso, Mariane; Porporatti, André Luís; Aydinoz, Secil; Canto, Graziela De Luca; Mezzomo, Luis Andre Mendonça; Bolan, Michele (March 2016). "Signs and Symptoms of Primary Tooth Eruption: A Meta-analysis". Pediatrics. 137 (3): e20153501. doi: 10.1542/peds.2015-3501 . ISSN   1098-4275. PMID   26908659.
  12. ↑ Ash, Major M. and Stanley J. Nelson. Wheeler’s Dental Anatomy, Physiology, and Occlusion. 8th edition. 2003. P. 38, 41. ISBN   0-7216-9382-2.
  13. ↑ Ash, Major M. and Stanley J. Nelson. Wheeler’s Dental Anatomy, Physiology, and Occlusion. 8th edition. 2003. P. 38. ISBN   0-7216-9382-2.
  14. ↑ WebMd. "Dental Health: Your Child's Teeth". Retrieved December 12, 2005.
  15. ↑ Ash, Major M.; Nelson, Stanley J. (2003). Wheeler's Dental Anatomy, Physiology, and Occlusion (8th ed.). p.  41. ISBN   0-7216-9382-2.
  16. ↑ "Permanent teeth". American Dental Association.
  17. ↑ "Monthly Microscopy Explorations". Archived from the original on 1 December 2005. Retrieved 12 December 2005.
  18. ↑ "Exploration of the Month". January 1998. Archived from the original on 18 May 2006. Retrieved 12 December 2005.
  19. ↑ "Health Hawaii".
  20. ↑ "Primary Teeth: Importance and Care". Health Hawaii. Archived from the original on 17 May 2006. Retrieved 12 December 2005.
  21. ↑ The American Academy of Periodontology Archived 2005-12-14 at the Wayback Machine . "Oral Health Information for the Public" Archived 2006-12-09 at the Wayback Machine . Retrieved December 12, 2005.
  22. ↑ Alpiste-Illueca, Francisco (2011-01-01). "Altered passive eruption (APE): a little-known clinical situation". Medicina Oral, Patologia Oral y Cirugia Bucal. 16 (1): e100–104. doi: 10.4317/medoral.16.e100 . ISSN   1698-6946. PMID   20711147.
  23. ↑ Coslet, J. G.; Vanarsdall, R.; Weisgold, A. (1977-12-01). "Diagnosis and classification of delayed passive eruption of the dentogingival junction in the adult". The Alpha Omegan. 70 (3): 24–28. ISSN   0002-6417. PMID   276255.
  24. ↑ Wysocki, J. Philip Sapp; Lewis R. Eversole; George P. (2002). Contemporary oral and maxillofacial pathology (2nd ed.). St. Louis: Mosby. pp. 39–40. ISBN   0-323-01723-1.
  25. ↑ Cawson, R.A.; Odell, E.W. (2012). Cawson's essentials of oral pathology and oral medicine (8th ed.). Edinburgh: Churchill Livingstone. pp. 419–421. ISBN   978-0443-10125-0.
  26. ↑ Dean, Ralph E. McDonald; David R. Avery; Jeffrey A. (2004). Dentistry for the child and adolescent (8. ed.). St. Louis, Mo: Mosby. pp. 164–168, 190–194, 474. ISBN   0-323-02450-5.
  27. ↑ Regezi, Joseph A; Sciubba, James J; Jordan, Richard C K (2008). Oral Pathology: Clinical Pathologic Correlations (5th ed.). St Louis, Missouri: Saunders Elsevier. pp. 353–354.
  28. 1 2 Hanisch, Marcel; Hanisch, Lale; Kleinheinz, Johannes; Jung, Susanne (2018-03-15). "Primary failure of eruption (PFE): a systematic review". Head & Face Medicine. 14 (1): 5. doi:10.1186/s13005-018-0163-7. ISSN   1746-160X. PMC   5856369 . PMID   29544499.
  29. ↑ Machol, K.; Mendoza-Londono, R.; Lee, B.; Adam, M. P.; Everman, D. B.; Mirzaa, G. M.; Pagon, R. A.; Wallace, S. E.; Bean LJH; Gripp, K. W.; Amemiya, A. (1993). "Cleidocranial Dysplasia Spectrum Disorder". GeneReviews®. University of Washington, Seattle. PMID   20301686.
  30. ↑ Van Dyck, Julie; Cadenas de Llano-Pérula, Maria; Willems, Guy; Verdonck, Anna (July 2019). "Dental development in cleft lip and palate patients: A systematic review". Forensic Science International. 300: 63–74. doi:10.1016/j.forsciint.2019.04.011. ISSN   1872-6283. PMID   31075568. S2CID   145896625.
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