{{Infobox medical condition (new) | name = Microdontia | synonyms = | image = Microdontia.jpg | caption = Radiograph (X-ray) showing microdontia. Note also periapical lesion on the maxillary left lateral incisor. | pronounce = | field = Dentistry | symptoms = | complications = | onset = | duration = | types = | causes = | risks = | diagnosis = | differential = | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }}
'''Microdontia''' is a condition in which one or more teeth appear smaller than normal. In the generalized form, all teeth are involved. In the localized form, only a few teeth are involved. The most common teeth affected are the upper lateral incisors and third molars.
Teeth affected by microdontia may also have abnormal shape, and the abnormal size may affect the whole tooth, or only a part of the tooth.<ref name=Poulsen2009 />
==Definition== Males tend to have larger teeth than females,<ref name=Poulsen2009 /> and tooth size also varies by race.<ref name=Poulsen2009 /> Abnormal tooth size is defined by some as when the dimensions are more than 2 standard deviations from the average.<ref name=Poulsen2009>{{cite book| vauthors = Poulsen S, Koch G |title=Pediatric dentistry: a clinical approach|date=2013|publisher=Wiley-Blackwell|location=Chichester, UK|isbn=9781118687192|page=191|edition=2nd|url=https://books.google.com/books?id=7Xdh8wb6zFsC&pg=PA191}}</ref> Microdontia is when the teeth are abnormally small, and macrodontia is when the teeth are abnormally large.
==Classification== There are 3 types of microdontia: ===True generalized=== All the teeth are smaller than the normal size. True generalized microdontia is very rare, and occurs in pituitary dwarfism.<ref name=Ibsen2014 /><ref name=Regezi2012 /> Due to decreased levels of growth hormone the teeth fail to develop to a normal size.<ref name=Ibsen2014>{{cite book| vauthors = Ibsen OA, Phelan JA |title=Oral Pathology for the Dental Hygienist|date=2014|publisher=Elsevier Health Sciences|isbn=9780323291309|pages=164–165|edition=6th|url=https://books.google.com/books?id=nsvsAwAAQBAJ&pg=PA165}}</ref> ===Relative generalized=== All the teeth are normal size but appear smaller relative to enlarged jaws.<ref name=Regezi2012>{{cite book| vauthors = Regezi JA, Scuibba JJ, Jordan RC |title=Oral pathology : clinical pathologic correlations|date=2012|publisher=Elsevier/Saunders|location=St. Louis, Mo.|isbn=978-1-4557-0262-6|page=373|edition=6th}}</ref> Relative generalized microdontia may be the result of inheritance of a large jaw from one parent, and normal sized teeth from the other.<ref name=Ibsen2014 />
===Localized (focal)=== Localized microdontia is also termed focal, or pseudo-microdontia. A single tooth is smaller than normal.<ref name=Regezi2012 /> Localized microdontia is far more common than generalized microdontia,<ref name=Ibsen2014 /> and is often associated with hypodontia (reduced number of teeth).<ref name=Poulsen2009 /> The most commonly involved tooth in localized microdontia is the maxillary lateral incisor, which may also be shaped like an inverted cone (a "peg lateral").<ref name=Regezi2012 /> Peg laterals typically occur on both sides,<ref name=Ibsen2014 /> and have short roots.<ref name=Ibsen2014 /> Inheritance may be involved,<ref name=Ibsen2014 /> and the frequency of microdontia in the upper laterals is just under 1%.<ref name=Poulsen2009 /> The second most commonly involved tooth is the maxillary third molars,<ref name=Regezi2012 /> and after this supernumerary teeth.<ref name=Regezi2012 />
==Causes== There are many potential factors involved.<ref name=Laskaris2011>{{cite book|author1=Laskaris G|title=Color Atlas of Oral Diseases in Children and Adolescents|date=2011|publisher=Thieme|isbn=9783131604712|page=2|url=https://books.google.com/books?id=dRuF_G5yRO0C&pg=PA2}}</ref> {{columns-list|colwidth=30em| * Congenital hypopituitarism<ref name=Poulsen2009 /> * Ectodermal dysplasia<ref name=Poulsen2009 /> * Down syndrome<ref name=Poulsen2009 /> * Ionizing radiation to the jaws during tooth development (odontogenesis)<ref name=Poulsen2009 /> * Chemotherapy during tooth development<ref name=Laskaris2011 /> * Marshall syndrome<ref name=Laskaris2011 /> * Rieger syndrome<ref name=Laskaris2011 /> * Focal dermal hypoplasia<ref name=Laskaris2011 /> * Silver-Russell syndrome<ref name=Laskaris2011 /> * Williams syndrome<ref name=Laskaris2011 /> * Gorlin-Chaudhry-Moss syndrome<ref name=Laskaris2011 /> * Coffin–Siris syndrome<ref name=Laskaris2011 /> * Salamon syndrome<ref name=Laskaris2011 /> * Cleft lip and palate<ref name=Laskaris2011 /> }}
Others include trichorhinopharyngeal, odontotrichomelic, neuroectodermal and dermo-odontodysplasia syndromes.<ref name=Laskaris2011 />
==Treatment== Unerupted microdonts may require surgical removal to prevent the formation of cysts.<ref name=Ibsen2014 /> Erupted microdonts, peg laterals especially, may cause cosmetic concern. Such teeth may be restored to resemble normal sized teeth,<ref name=Ibsen2014 /> typically with composite build ups or crowns.<ref name=Laskaris2011 /> Orthodontics may be required in severe cases to close gaps between the teeth.<ref name=Laskaris2011 />
==Epidemiology== Females are affected more than males,<ref name=Laskaris2011 /> and the condition occurs in permanent (adult) teeth more than deciduous (baby teeth or milk teeth).<ref name=Laskaris2011 />
== References == {{Reflist}}
== External links == {{Medical resources | DiseasesDB = 35076 | ICD10 = {{ICD10|K|00|2|k|00}} | ICD9 = {{ICD9|520.2}} | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = }}
Category:Developmental tooth disorders {{oral pathology}}