Rare diseases · Sign or symptom
Microdontia
Decreased size of tooth
HP:0000691
What it means
Decreased size of the teeth, which can be defined as a mesiodistal tooth diameter (width) more than 2 SD below mean. Alternatively, an apparently decreased maximum width of tooth.
Standard reference has means and standard deviations by gender [Moyers et al, 1976]. It is easy to measure the width of teeth, for which reason the definition of microdontia can be made with reference to the width of the tooth. However, microdontia means that the overall size of the tooth is decreased. In microdontia, the gaps between the teeth, particularly the anterior upper and lower teeth, are increased, creating diastemata. This should be assessed and coded separately.
Rare diseases that can present with this62
Very common80–99%
14- Blepharophimosis-intellectual disability syndrome, Ohdo type
- Cataract-hypertrichosis-intellectual disability syndrome
- Cerebellar ataxia-ectodermal dysplasia syndrome
- CHIME syndrome
- Cranioectodermal dysplasia
- Craniolenticulosutural dysplasia
- Deafness with labyrinthine aplasia, microtia, and microdontia
- Dermoodontodysplasia
- Ectodermal dysplasia-intellectual disability-central nervous system malformation syndrome
- EEC syndrome
- Laron syndrome
- Odonto-onycho dysplasia-alopecia syndrome
- Stimmler syndrome
- X-linked hypohidrotic ectodermal dysplasia
Common30–79%
25- Ablepharon macrostomia syndrome
- Aphonia-deafness-retinal dystrophy-bifid halluces-intellectual disability syndrome
- B3GALT6-related spondylodysplastic Ehlers-Danlos syndrome
- Branchio-oculo-facial syndrome
- Cerebrooculonasal syndrome
- Down syndrome
- EEM syndrome
- Ellis-Van Creveld syndrome
- Fetal alcohol syndrome
- Johanson-Blizzard syndrome
- Kabuki syndrome
- Koolen-De Vries syndrome
- Laryngo-onycho-cutaneous syndrome
- Maxillonasal dysplasia
- Microcephalic osteodysplastic primordial dwarfism type II
- Mucopolysaccharidosis type 1
- Oculocerebral hypopigmentation syndrome, Cross type
- Oculocerebrofacial syndrome, Kaufman type
- Oligodontia
- Periodontal Ehlers-Danlos syndrome
- Schimke immuno-osseous dysplasia
- SHORT syndrome
- Tricho-dento-osseous syndrome
- Williams syndrome
- X-linked intellectual disability, Stevenson type
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Decreased width of tooth · Hypotrophic tooth · Small teeth · Small tooth · Tooth hypoplasia · Tooth hypotrophy · Underdeveloped tooth
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.