Anomalies 1: disorders of number, size and form Flashcards
How long after eruption of primary teeth is root formation complete?
12-18 months
How long after eruption of permanent teeth is root formation complete?
2-3 years
What are the 2 types of anomalies of tooth number?
hypodontia or supernumerary teeth
What is hypodontia?
the developmental absence of primary or permanent teeth
What is severe hypodontia (AKA oligodontia)?
the developmental absence of 6 or more teeth excluding 3rd permanent molars
What is anodontia?
the complete developmental absence of teeth
What is an example of a single gene defect causing hypodontia?
MSX1
What syndromes may hypodontia notably be a feature of?
- ectodermal dysplasia
- trisomy 21
- cleft lip and palate
- solitary median maxillary central incisor syndrome
What is an environmental aetiology of hypodontia?
sequels of severe disease and cancer treatment in early childhood
During what stage of tooth development does hypodontia occur?
initiation stage of dental development
What are the clinical features of hypodontia?
- failure of a primary tooth to exfoliate at the expected time
- a permanent tooth hasn’t erupted several months after the primary exfoliates
- teeth erupting out of sequence
- the contralateral tooth has been erupted for some time (>6 months should raise suspicion)
- other teeth appear unusually spaced
- primary may become infraoccluded
- often associated with microdontia
- associated with ectopic position of permanent teeth
- no tooth palpable in sulcus
What is infraocclusion?
primary tooth becomes ankylosed, child keeps on growing but the tooth is stuck in position so the rest of the child’s dentition and alveolus is growing normally around it
primary tooth looks ‘sunken’ or ‘submerged’
What is ectodermal dysplasia?
- a group of inherited conditions
- classic form is X-linked hypohydrotic but there are >180 identified types
What is affected by ectodermal dysplasia?
structures arising from ectoderm:
- teeth
- skin
- hair
- nails
- glands
What effects does ectodermal dysplasia have on teeth?
- very variable
- severe hypodontia, occasionally anodontia
- microdontia
- classic conical shaped teeth
What are the dental considerations in a patient with ectodermal dysplasia?
- function
- trauma
- aesthetics
- treatment fatigue
- xerostomia
- overclosure
- comfort in the dental surgery (heat)
- in some cases the dentist makes the diagnosis (subject the genetic confirmation)
What is the most well known/easily recognised type of ectodermal dysplasia?
X-linked hypohydrotic ED
What are some characteristic features of ectodermal dysplasia?
- characteristic features of sparse hair, dry skin, inability to sweat
- may also suffer form xerostomia, dry eyes and nasal congestion
- characteristic conical appearance of teeth, microdontia and hypodontia of multiple teeth
What is the role of the GDP in the management of hypodontia?
- early detection
- prevention of caries, perio
- referral
What is the role of the multidisciplinary team in the management of hypodontia?
- confirmation of diagnosis
- coordination of care - paeds, restorative, ortho, GDP
- redistribution of space
finish from PPT
What are supernumerary teeth?
the presence of a tooth/teeth in addition to the normal sequence
At what stage of development do supernumerary teeth occur?
initiation stage of tooth formation
What is the aetiology of supernumerary teeth?
- genetic, often runs in families
- a feature of some syndromes
What syndromes may supernumerary teeth be a feature of?
- cleidocranial dysplasia
- cleft lip and palate
- gardner syndrome
What can supernumerary teeth be defined by?
position and/or shape
What positions can supernumerary teeth be defined by?
mesiodens, paramolar
What shapes can supernumerary teeth be defined by?
- conical
- tuberculate
- supplemental
- odontome
What are the features of conical supernumerary teeth?
- most common (~75%)
- likely to erupt if not inverted, but not always
- often but not always impede eruption of other teeth
- often occurs in midline maxilla
- often in pairs
- often inverted
What are the features of tuberculate supernumerary teeth?
- ~12%
- barrel shaped
- do not usually erupt
- very likely to impede eruption of other teeth
- often occur in pairs
What are the features of supplemental supernumerary teeth?
- ~7%
- has normal anatomy
- often a supplemental lateral incisor, 3rd premolar or 4th molar
- likely to erupt, particularly supplemental incisors
- less likely than other types to impede eruption
What are the features of odontome supernumerary teeth?
- ~6%
- collection of tooth tissue
- compound: denticules
- complex: disorganised collection of tooth tissue
- will not erupt
- very likely to impede eruption of nearby teeth
What are the clinical features of supernumerary teeth?
- first sign by be eruption of supernumerary or delayed eruption of normal sequence
- may cause crowding, rotation, malposition, ectopic positon of surrounding teeth
- frequently in anterior maxilla, common cause of delayed eruption of central incisor
- clinical examination should include palpation for the presence and positon of unerupted teeth
What is involved in the management of supernumerary teeth?
- monitor
- simple extraction
- surgical extraction
- teeth which have been impeded may need to be surgically exposed +/- orthodontically repositioned
What is cleidocranial dystosis?
rare autosomal dominant condition
What are the characteristics or cleidocranial dystosis?
- hypoplastic or absent clavicles, short stature, characteristics facial features
- dental features include multiple supernumerary teeth, delayed/failures exfoliation of primary teeth and delayed/failed eruption of permanent teeth
What is the management of cleidocranial dystosis?
- multiple, complex surgeries required and orthodontic treatment
- treatment occurs in multiple stages and lasts many years
Is it always necessary to extract supernumerary teeth?
no, may not always cause problems
What is microdontia?
smaller the average tooth/teeth
During what stage of development does microdontia occur?
morphogenesis stage of tooth formation
What is the aetiology of microdontia?
- genetic component
- environmental e.g. childhood illness, cancer treatment
- associated with hypodontia
- associated with syndromes:
- ectodermal dysplasia
- cleft lip and palate