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- 35-50% of cases in the primary dentition superseded by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
tx options fro double teeth?
- no intervention needed in primary dentition
- Be wary of anomalies in the permanent dentition including: hypodontia and supernumaries (30-50% penetrance)
- Be wary of caries at the interface between the 2 crown segments,
especially if extending subgingival – may want to restore any notch for aesthetic and preventative reasons - If 2 separate root canals – can surgically divide
- Extraction
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
how do we manage invagination ?
- Although defects are generally enamel lined, this can be of poor
quality and very thin - Difficulty cleaning means high caries risk and bacterial ingress to the
pulp leading to pulpal disease - Can try to maintain less severe forms with adhesive restorations
- Early intervention is key!
- Can attempt RCT but often challenging due to abnormal morphology
- If grossly abnormal, extraction may be the best option with space
closure of prosthetic replacement
what are accessory cusps ? prevalence ?
- Can affect primary and secondary dentition
- Fairly common – 10 - 60% of people have a cusp of Carabelli on an
upper 6 (depending on population studied) - ‘Talon cusp’ on maxillary incisors – check for caries at interface
- Size and pulpal involvement varies
- If causing occlusal interferences may
need to be reduced - If extensive reduction may require
a pulpotomy
what is dilacertion ?
- An abrupt deviation along the long axis of the crown or root
- Upper incisors most commonly affected
- Can lead to failure of eruption
what is the management for dilaceration ?
- If less marked divergence, can expose, bond traction and attempt orthodontic alignment – need to consider where the
root will end up once the crown is aligned - If more significant, will likely need to remove – extraction can be challenging!
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
when would w investigate delayed eruption further ?
there can be great individual variation interruption times in permanent dentition:
* Eruption sequence is therefore most important
* If a tooth still hasn’t erupted > 6/12 after its contralateral, =investigate
Generalised delayed eruption isn’t a cause for concern nor does it require any intervention other than reassurance
Localised delays often do require intervention
list some systematic conditions leading to delayed eruption ?
list some local factors leading to delayed eruption ?
what are the 2 types of transpositions ?
pseuodetranspostion = just crown that are in swapped position
true transposition = whole tooth tooth including the root in wrong position
most common transposition = maxillary lateral incisor - canine transposition
what are the 2 types of unerupted teeth ?
- Ectopic – developed in abnormal place or position
- Impacted – physical impediment to eruption by another structures such as bone, adjacent teeth, soft tissues
what sorts of problems arrise around upper 1’s?
dilacerations or obstructions
what sorts of issues arise with upper and lower 5’s ?
lack of space/ obstruction
what sorts or issues arise with upper 6s ?
impaction into E’s
what sorts of issue arise with upper and lower 8’s ?
lack of space in arch causing impaction
what is the prevalence of unerupted upper canines ?
2% maxillary canines (Caucasian)
61% palatal / 34% in line of arch / 4.5% buccal (ectopic)
Female : Male 7 : 3
what is the aetiology of unerupted upper canines ?
Polygenic and multifactorial
Genetic theory
* Family history
* > frequency bilateral than expected
* Associated malformations
Guidance theory / local factors
* Missing or absent lateral incisor (helps guide canine)
* Retention of 1ry canine
* Crowding
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
how do we screen for canines ?
Majority of normal erupting maxillary canines should be
palpable in the buccal sulcus by 10 years old
CaNINE! – Start palpating at 9
Considered late if not erupted before 12.3 years in girls and
13.1 years in boys
Both U3s should erupt within 6 months of each other
< 0.1% of U3s are developmentally absent
If can’t palpate by 10, consider referral for specialist opinion
what is ankylosis (failure of eruption)? why does it happen?
Uncommon, isolated condition causing a localised failure of eruption of a single tooth with no other identifiable causes
* No obvious impediment to eruption
* Other teeth apparently normal
* May partially erupt and then appear to submerge due to continued vertical growth of the rest of the alveolar complex
* The teeth fail to respond to orthodontic forces – often removal is indicated
* Localised disturbances in metabolism or trauma often implicated. May have a genetic component.
what is primary failure of eruption? consequences ? causes?
- Rare, isolated condition causing localised failure of eruption of
multiple teeth with no other identifiable causes - Primarily affects posterior teeth
- Affects all teeth posterior to the most anteriorly affected tooth
- Leads to a lateral open bite
- The teeth fail to respond to orthodontic forces
- Generally restorative options required to manage
- Strong genetic component – PTH1R
what are some conditions/ syndromes commonly associated with dental anomalies more commonly seen in ortho?
- cleft lip and palate
- downs
- Hypohydrotic Ectodermal Dysplasia
- Cleidocranial Dysostosis
what is cleft lip and palate? prevalence ?
- most common
- 1 in 700 to 1 in 1000 live births (Caucasians)
- More common in Asian (1:500) and less common in African
(1:2500) populations - 2 : 1 Males : Females
what is cleft palate syndrome?
- 1 in 2000 live births (Caucasians), but less racial variation
- 4 : 1 Females : Males
- doesn’t affect lip
how much of CP and CLP are syndromic? and what are the syndromes ?
Treacher Collins, van der Woude, hypohydrotic ectodermal
dysplasia, Down syndrome
label diagram
a= unilateral CL
b= bilateral CL
c= unilateral CLP
d= bilateral CLP
e= isolated CP
what is downs and what are the key dental findings?
- 1 in 700 live births overall, risk increases with maternal age
- Trisomy of chromosome 21
- Myriad signs and symptoms
- Key dental findings include
- Class III malocclusion - maxillary hypoplasia
- Hypodontia
- CLP
- Microdontia
- Delayed eruption of 2ry dentition
- Short roots
what is Hypohydrotic Ectodermal Dysplasia? dental relevance ?
- Smooth dry skin with sparse hair
- Partial / total absence of sweat glands
(hypohydrotic) - Key dental findings include
- Class III malocclusion
- Anodontia / severe hypodontia
- Deformed teeth / conical crowns
- Delayed eruption
- Xerostomia
- CLP
what is Cleidocranial Dysostosis?
- Cleido - Absent / hypoplastic clavicles
- Cranial - Fontanelles and sutures persist, helmet-like skull
- Autosomal dominant - mutation in CBFA1/RUNX2 gene
- Key dental findings include:
- Class III malocclusion - Mx hypoplasia
- Multiple supernumerary teeth
- Dentigerous cysts
- Retained 1ry teeth
- Failure of eruption of 2ry teeth
