Editing Human tooth (section)

==Abnormalities==
[[File:Fracturedtooth.jpg|thumb|A broken upper front tooth showing the pink of the pulp]]
Tooth abnormalities may be categorized according to whether they have environmental or developmental causes.<ref name="neville50">{{harvnb|Neville|2002|page=50.}}</ref> While environmental abnormalities may appear to have an obvious cause, there may not appear to be any known cause for some developmental abnormalities. Environmental forces may affect teeth during development, destroy tooth structure after development, discolor teeth at any stage of development, or alter the course of tooth eruption. Developmental abnormalities most commonly affect the number, size, shape, and structure of teeth.

===Environmental===

==== Alteration during tooth development ====
Tooth abnormalities caused by environmental factors during tooth development have long-lasting effects. Enamel and dentin do not regenerate after they mineralize initially. [[Enamel hypoplasia]] is a condition in which the amount of enamel formed is inadequate.<ref>{{harvnb|Ash|2003|page=31}}</ref> This results either in pits and grooves in areas of the tooth or in widespread absence of enamel. Diffuse opacities of enamel does not affect the amount of enamel but changes its appearance. Affected enamel has a different translucency than the rest of the tooth. Demarcated opacities of enamel have sharp boundaries where the translucency decreases and manifest a white, cream, yellow, or brown color. All these may be caused by nutritional factors,<ref name=KanchanMachado2015>{{cite journal|vauthors= Kanchan T, Machado M, Rao A, Krishan K, Garg AK|title=Enamel hypoplasia and its role in identification of individuals: A review of literature|date=Apr 2015|journal=Indian J Dent|volume=6|issue=2|pages=99–102|doi=10.4103/0975-962X.155887|pmid=26097340|pmc=4455163|type=Revisión |doi-access=free }}</ref> an [[exanthem]]atous disease ([[chicken pox]], [[congenital syphilis]]),<ref name=KanchanMachado2015 /><ref name="neville51">{{harvnb|Neville|2002|page= 51}}</ref> undiagnosed and untreated [[coeliac disease|celiac disease]],<ref name=NIH>[http://celiac.nih.gov/PDF/Dental_Enamel_Defects_508.pdf Dental Enamel Defects and Celiac Disease] {{Webarchive|url=https://web.archive.org/web/20160305124250/http://celiac.nih.gov/PDF/Dental_Enamel_Defects_508.pdf |date=2016-03-05 }} National Institute of Health (NIH)</ref><ref name=FerrazCampos2012>{{cite journal|vauthors=Ferraz EG, Campos Ede J, Sarmento VA, Silva LR|title=The oral manifestations of celiac disease: information for the pediatric dentist|date=2012|journal=Pediatr Dent|volume=34|issue=7|pages=485–8|pmid=23265166|type=Review}}</ref><ref name=GiucaCei2010>{{cite journal|vauthors=Giuca MR, Cei G, Gigli F, Gandini P|title=Oral signs in the diagnosis of celiac disease: review of the literature|date=2010|journal=Minerva Stomatol|volume=59|issue=1–2|pages=33–43|pmid=20212408|type=Review}}</ref> [[hypocalcaemia|hypocalcemia]], [[dental fluorosis]], [[birth injury]], [[preterm birth]], [[infection]] or trauma from a [[deciduous teeth|deciduous tooth]].<ref name=KanchanMachado2015 /> Dental fluorosis is a condition which results from ingesting excessive amounts of [[fluoride]] and leads to teeth which are spotted, yellow, brown, black or sometimes pitted. In most cases, the enamel defects caused by celiac disease, which may be the only manifestation of this disease in the absence of any other symptoms or signs, are not recognized and mistakenly attributed to other causes, such as fluorosis.<ref name=NIH /> Enamel hypoplasia resulting from [[syphilis]] is frequently referred to as [[Hutchinson's teeth]], which is considered one part of [[Hutchinson's triad]].<ref>[http://www.mayoclinic.com/health/syphilis/DS00374/DSECTION=6 Syphilis: Complications], Mayo Clinic.</ref> [[Turner's hypoplasia]] is a portion of missing or diminished enamel on a permanent tooth usually from a prior infection of a nearby primary tooth. Hypoplasia may also result from [[antineoplastic]] therapy.

====Destruction after development====
Tooth destruction from processes other than [[dental caries]] is considered a normal physiologic process but may become severe enough to become a pathologic condition. [[Attrition (dental)|Attrition]] is the loss of tooth structure by mechanical forces from opposing teeth.<ref>"[http://www.adha.org/CE_courses/course9/loss_of_structure.htm Loss of Tooth Structure] {{Webarchive|url=https://web.archive.org/web/20121227091702/http://www.adha.org/CE_courses/course9/loss_of_structure.htm |date=2012-12-27 }}", American Dental Hygiene Association.</ref> Attrition initially affects the enamel and, if unchecked, may proceed to the underlying dentin. [[Abrasion (dental)|Abrasion]] is the loss of tooth structure by mechanical forces from a foreign element.<ref>"[https://web.archive.org/web/20100801114913/http://dentistry.umkc.edu/practition/assets/AbnormalitiesofTeeth.pdf Abnormalities of Teeth]", University of Missouri-Kansas City School of Dentistry.</ref> If this force begins at the cementoenamel junction, then progression of tooth loss can be rapid since enamel is very thin in this region of the tooth. A common source of this type of tooth wear is excessive force when using a toothbrush. [[Erosion (dental)|Erosion]] is the loss of tooth structure due to chemical dissolution by acids not of bacterial origin.<ref>{{cite journal|url=http://www.agd.org/library/2003/aug/200308_yip.pdf |pmid=15055615 |year=2003 |last1=Yip |first1=KH |last2=Smales |first2=RJ |last3=Kaidonis |first3=JA |title=The diagnosis and control of extrinsic acid erosion of tooth substance |volume=51 |issue=4 |pages=350–3; quiz 354 |journal=General Dentistry |url-status=dead |archive-url=https://web.archive.org/web/20060907094153/http://www.agd.org/library/2003/aug/200308_yip.pdf |archive-date=September 7, 2006 }}</ref> Signs of tooth destruction from erosion is a common characteristic in the mouths of people with [[bulimia]] since [[vomiting]] results in exposure of the teeth to gastric acids. Another important source of erosive acids are from frequent sucking of [[lemon juice]]. [[Abfraction]] is the loss of tooth structure from flexural forces. As teeth flex under [[pressure]], the arrangement of teeth touching each other, known as [[occlusion (dentistry)|occlusion]], causes [[Tension (mechanics)|tension]] on one side of the tooth and [[compression (physical)|compression]] on the other side of the tooth. This is believed to cause V-shaped depressions on the side under tension and C-shaped depressions on the side under compression. When tooth destruction occurs at the roots of teeth, the process is referred to as [[internal resorption]], when caused by cells within the pulp, or [[external resorption]], when caused by cells in the periodontal ligament.

====Discoloration====
{{Main|Tooth discoloration}}
[[File:Tired teeth.jpg|thumb|Discolored teeth]]
Discoloration of teeth may result from bacteria stains, tobacco, tea, coffee, foods with an abundance of [[chlorophyll]], restorative materials, and medications.<ref name="neville63">{{harvnb|Neville|2002|page= 63}}</ref> Stains from bacteria may cause colors varying from green to black to orange. Green stains also result from foods with chlorophyll or excessive exposure to copper or nickel. Amalgam, a common dental restorative material, may turn adjacent areas of teeth black or gray. Long term use of [[chlorhexidine]], a mouthwash, may encourage extrinsic stain formation near the gingiva on teeth. This is usually easy for a hygienist to remove. Systemic disorders also can cause tooth discoloration. [[Congenital erythropoietic porphyria]] causes [[porphyrin]]s to be deposited in teeth, causing a red-brown coloration. Blue discoloration may occur with [[alkaptonuria]] and rarely with [[Parkinson's disease]]. [[Erythroblastosis fetalis]] and [[biliary atresia]] are diseases which may cause teeth to appear green from the deposition of [[biliverdin]]. Also, trauma may change a tooth to a pink, yellow, or dark gray color. Pink and red discolorations are also associated in patients with [[leprosy|lepromatous leprosy]]. Some medications, such as [[tetracycline]] antibiotics, may become incorporated into the structure of a tooth, causing intrinsic staining of the teeth.

====Alteration of eruption====
Tooth eruption may be altered by some environmental factors. When eruption is prematurely stopped, the tooth is said to be [[Wisdom teeth#Impaction|impacted]]. The most common cause of tooth impaction is lack of space in the mouth for the tooth.<ref name="neville66">{{harvnb|Neville|2002|page=66}}</ref> Other causes may be [[tumor]]s, [[cyst]]s, trauma, and thickened bone or soft tissue. [[Tooth ankylosis]] occurs when the tooth has already erupted into the mouth but the cementum or dentin has fused with the alveolar bone. This may cause a person to retain their primary tooth instead of having it replaced by a permanent one.

A technique for altering the natural progression of eruption is employed by [[orthodontist]]s who wish to delay or speed up the eruption of certain teeth for reasons of space maintenance or otherwise preventing crowding and/or spacing. If a primary tooth is extracted before its succeeding permanent tooth's root reaches {{frac|1|3}} of its total growth, the eruption of the permanent tooth will be delayed. Conversely, if the roots of the permanent tooth are more than {{frac|2|3}} complete, the eruption of the permanent tooth will be accelerated. Between {{frac|1|3}} and {{frac|2|3}}, it is unknown exactly what will occur to the speed of eruption.

===Developmental===

==== Abnormality in number ====
* [[Anodontia]] is the total lack of tooth development.
* [[Hyperdontia]] is the presence of a higher-than-normal number of teeth.
* [[Hypodontia]] is the lack of development of one or more teeth.
** Oligodontia may be used to describe the absence of 6 or more teeth.
Some systemic disorders which may result in hyperdontia include [[Apert syndrome]], [[cleidocranial dysostosis]], [[Crouzon syndrome]], [[Ehlers–Danlos syndrome]], [[Gardner's syndrome]], and [[Sturge–Weber syndrome]].<ref name="neville70">{{harvnb|Neville|2002|page=70}}</ref> Some systemic disorders which may result in hypodontia include Crouzon syndrome, [[Ectodermal dysplasia]], Ehlers–Danlos syndrome, and [[Gorlin syndrome]].<ref name="neville69">{{harvnb|Neville|2002|page=69}}</ref>

====Abnormality in size====
* [[Microdontia]] is a condition where teeth are smaller than the usual size.
* [[Macrodontia (tooth)|Macrodontia]] is where teeth are larger than the usual size.

Microdontia of a single tooth is more likely to occur in a [[maxillary lateral incisor]]. The second most likely tooth to have microdontia are [[wisdom teeth|third molars]]. Macrodontia of all the teeth is known to occur in [[Gigantism|pituitary gigantism]] and [[Pineal gland|pineal]] [[hyperplasia]]. It may also occur on one side of the face in cases of [[hemifacial hyperplasia]].

====Abnormality in shape====
[[File:Milk.teeth.fusion.jpg|thumb|The fusion of two deciduous teeth]]
* [[Tooth Gemination|Gemination]] occurs when a developing tooth incompletely splits into the formation of two teeth.
* [[Tooth fusion|Fusion]] is the union of two adjacent teeth during development.
* [[Concrescence]] is the fusion of two separate teeth only in their cementum.
* Accessory [[Cusp (dentistry)|cusps]] are additional cusps on a tooth and may manifest as a [[Talon cusp]], [[Cusp of Carabelli]], or [[Dens evaginatus]].
* [[Dens invaginatus]], also called Dens in dente, is a deep invagination in a tooth causing the appearance of a tooth within a tooth.
* [[Ectopic enamel]] is enamel found in an unusual location, such as the root of a tooth.
* [[Taurodontism]] is a condition where the body of the tooth and pulp chamber is enlarged, and is associated with [[Klinefelter syndrome]], [[Tricho-dento-osseous syndrome]], [[Triple X syndrome]], and [[XYY syndrome]].<ref name = "neville85"/>
* [[Hypercementosis]] is excessive formation of cementum, which may result from trauma, inflammation, [[acromegaly]], [[rheumatic fever]], and [[Paget's disease of bone]].<ref name="neville85">{{harvnb|Neville|2002|page=85}}</ref>
* A [[dilaceration]] is a bend in the root which may have been caused by trauma to the tooth during formation.
* [[Supernumerary roots]] is the presence of a greater number of roots on a tooth than expected

==== Cleft lip and palate and their association with dental anomalies ====
There are many types of dental anomalies seen in cleft lip and palate (CLP) patients. Both sets of dentition may be affected; however, they are commonly seen in the affected side. Most frequently, missing teeth, supernumerary or discoloured teeth can be seen; however, enamel dysplasia, discolouration and delayed root development are also common. In children with cleft lip and palate, the lateral incisor in the alveolar cleft region has the highest prevalence of dental developmental disorders;<ref>{{Cite journal|vauthors=Tortora C, Meazzini MC, Garattini G, Brusati R|date=March 2008|title=Prevalence of abnormalities in dental structure, position and eruption pattern in population of unilateral and bilateral cleft lip and palate patients|pmid=18333651|doi=10.1597/06-218.1|journal=The Cleft Palate-Craniofacial Journal|volume=45|issue=2|pages=154–162|s2cid=23991279}}</ref> this condition may be a cause of tooth crowding.<ref>{{Cite web|date=2020-06-29|title=Dental Crowding: Causes and Treatment Options|url=https://orthodonticsaustralia.org.au/dental-crowding-causes-and-treatment-options/|access-date=2021-02-06|website=Orthodontics Australia|language=en-AU}}</ref> This is important to consider in order to correctly plan treatment keeping in mind considerations for function and aesthetics. By correctly coordinating management invasive treatment procedures can be prevented resulting in successful and conservative treatment.

There have been a plethora of research studies to calculate prevalence of certain dental anomalies in CLP populations however a variety of results have been obtained.

In a study evaluating dental anomalies in Brazilian cleft patients, male patients had a higher incidence of CLP, agenesis, and supernumerary teeth than did female patients. In cases of complete CLP, the left maxillary lateral incisor was the most commonly absent tooth. Supernumerary teeth were typically located distal to the cleft.<ref>{{cite journal|title=Characteristics and distribution of dental anomalies in a Brazilian cleft population|author1=Luciane Macedo de Menezes |author2=Susana Maria Deon Rizzatto |author3=Fabiane Azeredo |author4=Diogo Antunes Vargas|journal=Revista Odonto Ciência|volume=25|issue=2|pages=137–141 |year=2010|doi=10.1590/S1980-65232010000200006|doi-access=free}}</ref> In a study of Jordanian subjects, the prevalence of dental anomaly was higher in CLP patients than in normal subjects. Missing teeth were observed in 66.7% of patients, with maxillary lateral incisor as the most frequently affected tooth. Supernumerary teeth were observed in 16.7% of patients; other findings included microdontia (37%), taurodontism (70.5%), transposition or ectopic teeth (30.8%), dilacerations (19.2%), and hypoplasia (30.8%). The incidence of microdontia, dilaceration, and hypoplasia was significantly higher in bilateral CLP patients than in unilateral CLP patients, and none of the anomalies showed any significant sexual dimorphism.<ref>{{Cite journal|vauthors=Al Jamal GA, Hazza'a AM, Rawashdeh MA|year=2010|title=Prevalence of dental anomalies in a population of cleft lip and palate patients|journal=The Cleft Palate-Craniofacial Journal|volume=47|issue=4|pages=413–420|doi=10.1597/08-275.1|pmid=    20590463|s2cid=7220626}}</ref>

It is therefore evident that patients with cleft lip and palate may present with a variety of dental anomalies. It is essential to assess the patient both clinically and radiographically in order to correctly treat and prevent progression of any dental problems. It is also useful to note that patients with a cleft lip and palate automatically score a 5 on the IOTN ( index for orthodontic need) and therefore are eligible for orthodontic treatment, liaising with an orthodontist is vital in order coordinate and plan treatment successfully.

====Abnormality in structure====
* [[Amelogenesis imperfecta]] is a condition in which enamel does not form properly or at all.<ref>[http://ghr.nlm.nih.gov/condition=amelogenesisimperfecta Amelogenesis imperfecta], Genetics Home Reference, a service of the U.S. National Library of Medicine.</ref>
* [[Dentinogenesis imperfecta]] is a condition in which dentin does not form properly and is sometimes associated with [[osteogenesis imperfecta]].<ref>[http://ghr.nlm.nih.gov/condition=dentinogenesisimperfecta Dentinogenesis imperfecta], Genetics Home Reference, a service of the U.S. National Library of Medicine.</ref>
* [[Dentin dysplasia]] is a disorder in which the roots and pulp of teeth may be affected.
* [[Regional odontodysplasia]] is a disorder affecting enamel, dentin, and pulp and causes the teeth to appear "ghostly" on radiographs.<ref>{{cite journal|author=Cho, Shiu-yin|url=http://www.cda-adc.ca/jcda/vol-72/issue-8/vol72_issue8.pdf |title=Conservative Management of Regional Odontodysplasia: Case Report|volume=72|issue =8|pages=735–8|pmid=17049109|year=2006|journal=J Can Dent Assoc}}</ref>
* [[Diastema]] is a condition in which there is a gap between two teeth caused by the imbalance in the relationship between the jaw and the size of teeth.<ref>''ASDC Journal of Dentistry for Children, Volume 48''. American Society of Dentistry for Children, 1980. p. 266</ref>