Developmental anomalies in orthodontics Flashcards
define supernumeraries ?
A tooth (or tooth-like structure) that is additional to the normal
series
what is the incidence of supernumeraries ?
- 2-4% permanent dentition, 0.8% primary dentition (Caucasians)
- 35-50% of cases in the primary dentition superseded by
supernumerary in the permanent dentition - In the permanent dentition = twice as common in males and maxilla 5 times more common than mandible
how do we classify supernumeraries ?
by form or site
- FORM
* Supplemental – extra tooth of normal (ish) form
* Conical – generally early forming and peg shaped
* Tuberculate – generally late forming and barrel shaped
* Odontome ( a mass of dental structures) :
- CompounD – Containing many small separate tooth like
structures (denticles) – usually found anteriorly
- Complex – a large mass of disorganised enamel and dentine
– usually found posteriorly - SITE
* Mesiodens – midline between the central incisors
* Paramolar / parapremolar – adjacent to the molars / premolars
* Distodens/Distomolar – distal to the arch
what is the most common supernumerary ?
conical
where are conicals usually found ?
midline so mesiodens - can cause diastema
- can erupt in palate
when do conicals form?
- root formation is usually ahead or with the permanent incisors
- unlikely to cause problems ie. impede eruption and may itself erupt
how do we manage conicals ?
if high and will not interfere with ortho tx = can be left
- the risk of cystic change or resorption is low
tuberculate: describe them? when are they formed ? when do they erupt? management ?
- Barrel shaped
- Root formation delayed compared to
permanent incisor - Usually palatal
- More likely to impede eruption
- Often occur in pairs
- Usually need to be removed
what are some associated conditions with supernumeraries ?
- Cleft lip and palate
- Gardner’s syndrome
- Cleidocranial dysostosis
what are some of the problems associates with supernumeraries ?
In the permanent dentition, the majority fail to erupt and are incidental radiographic findings.
However, they can:
* Impede eruption of other teeth
* Cause displacement or rotation of erupted teeth
* Produce spacing between erupted teeth
* Contribute to crowding if they erupt
* Undergo cystic change
what can cystic change cause ?
swelling
resorption of roots
displacement of teeth
discomfort
what is hypodontia? prevalence ?
- The developmental absence of one or more teeth
(excluding 8s – 25% to 35% absent) - Prevalence of 6.4% (varies amongst populations)
- L5s (2.6%) > U2s (2%) > U5s > L 1s
- Genetic aetiology - MSX1, PAX9 and AXIN2
- Females 3:2
how can we classify hypodontia?
- Mild (1-2), moderate (3-5) and severe (>6)
- or
- Hypodontia – absence of <6
- Oligodontia –absence of ≥6 teeth
- Anodontia – absence of all teeth
what are some associated conditions of hypodontia ?
- Cleft lip and palate
- Downs syndrome
- Ectodermal dysplasia
How do we treat hypodontia ?
- open space and replace missing teeth with prosthetics
- orthodontics and camouflage teeth
what is microdontia? prevalence ?
- Teeth which have smaller than average dimensions – range from
mildl to severe - Can affect the crown, the root or the whole tooth
- Most likely genetic aetiology
- Around 2.5% of people have at least one microdont tooth
- Can affect just one tooth, many teeth or even the entire dentition
(although this is rare and generally associated with an underlying
syndrome) - Upper 2s are most commonly affected – ‘peg’ laterals
- Often see one peg upper 2 and one missing upper 2
tx option for microdontia?
- Accept – generally done if mild or in a less aesthetically
challenging area e.g. upper 7s - Create space to have the microdont teeth built up
- Extract the microdont tooth and close the space
what is macrodontia ?
- Teeth which have larger than average dimensions
- Can affect the crown, the root or the whole tooth
- Most likely genetic aetiology
- Around 1% of people have at least one megadont tooth
- Upper 1s / lower 5s are most commonly affected – often
bilateral - Often but not always can be differentiated from a ‘double
tooth’ by lack of coronal notching and normal pulpal form
tx options for macrodontia?
- Accept – generally done if mild or in a less aesthetically
challenging area e.g. lower 5s - Extract and reduce space for a normally sized prosthesis
- Extract and close space
- Camouflage restoratively to resemble 2 teeth e.g. if a very large
upper 1 and missing upper 2
what is double teeth ? prevalence?
- some cases in macrodontia we can get double teeth. They can be because of fusion or germination.
- Fusion – of 2 separate tooth germs leading to a reduced number
of teeth in the arch - Gemination – developmental
- you can investigate from radiographs and clinically separation of a single tooth germ
- More common in primary (0.5-1.6%) than secondary (0.1-0.2%)
dentition and anteriorly rather than posteriorly - Males : Female 1 : 1
- Clinically varies from a small notch on a wide crown / root to 2 apparently separate crowns with a shared root
- Concrescence – fusion of the roots only (frequently terminal
molars)
what is a related condition to double teeth ?
concrescence- cementum of 2 adjacent teeth fuses
- this happens usually with 6s or 7s
- can only diagnosed via cbct
can make extractions difficult
what is invagination? prevalence ?
An enamel lined ‘infolding’ in the crown of a tooth, which can extend
into the root
- 1 – 5% of people depending on ethnicity and inclusion criteria
- Produced by an invagination of the enamel epithelium into the dental
papilla during development - Upper 2s most commonly affected, followed by upper 1s
- Milder forms appear similar to a deep cingulum pit (Dens Invaginatus)
- In more severe forms the invagination starting at the incisal edge (Dens
in Dente) and can lead to a grossly abnormal crown and root
aetiology of dilacerations (kink) ?
TRAUMATIC – due to intrusion of a primary incisor into developing tooth germ
* Position of dilaceration corresponds with stage of development at time of trauma
* Generally crown angled palatally and hypoplasia seen at the site of dilaceration
DEVELOPMENTAL – may be due to an obstruction of the eruption path
* Generally crown angled upward and labially and no hypoplasia is
seen
- upper 1’s most commonly affected
list some systematic conditions leading to delayed eruption ?
list some local factors leading to delayed eruption ?
what are some of the consequences of unerupted upper canines ?
Root resorption
* Up to 2/3 U2s have RR when U3s
ectopic
* Most RR occurs before 14
* How much is clinically significant?
Coronal resorption
* Most likely in adults
Cystic change
* Generally thought to be low risk,
especially in older patients
label diagram
a= unilateral CL
b= bilateral CL
c= unilateral CLP
d= bilateral CLP
e= isolated CP
