ortho perspective on developmental anomalies Flashcards
are supernumeraries more common is men or women?
Men, twice as much as women
how are the conical-shaped teeth characterised and are they late forming or early forming?
peg shaped, early forming
how are the Tuberculate-shaped teeth characterised and are they late forming or early forming?
barrel shaped, late forming
name the different groups when classifying teeth by form/shape
1- Supplemental (extra tooth of normal (ish) form
3 - Conical – generally early forming and peg-shaped
3 - Tuberculate – generally late forming and barrel-shaped
4 - Odontome
what are the two different presentations of odontomas
- Compound – Containing many small separate tooth-like structures (denticles) –usually found anteriorly
- Complex – a large mass of disorganised enamel and dentine – usually found posteriorly
name the different groups when classifying teeth by site/ position
- Mesiodens – midline between the central incisors
- Paramolar / para premolar – adjacent to the molars/premolars
- Distodens/Distomolar – distal to the arch
where are the conical teeth usually found and what are the consequences on teeth appearance if they erupt
- they are usually found in the midline (mesiodens)
- if they erupt, they cause diastema
what is the risk of cystic formation and eruption impeding in the conical teeth
- low risk of impeding eruption and may erupt
- low risk of cystic formation or resorption
- Do Tuberculate teeth impede eruption?
- where does it usually found?
- is it fine to be left or does it need to be removed?
- yes they are more likely to impede eruption
- often found palatally
- need to be removed
what are the conditions associated with supernumerary?
- Gardner syndrome
- Cleidocranial dysostosis
- Cleft lip and palate
What does Gardner syndrome cause? and what condition of teeth is it associated with?
- associated with supernumerary
- a very rare inherited syndrome, which causes multiple precancerous polyps in the colon as well as tumours elsewhere, which can include osteomas in the skull.
- What does Cleidocranial dysostosis cause?
- What condition of teeth is it associated with?
- associated with supernumerary
- This condition which either inherited or a new mutation on the RUNX2 gene.
- Cleido – refers to the collarbones, and cranial refers to the skull.
- It causes the collarbones to be partly or completely missing, a hypoplastic maxilla making them usually look class III, and they will also often have multiple supernumerary teeth.
What are the problems with supernumerary teeth?
- 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 genes associated with Hypodontia
MSX1
PAX9
AXIN2
what are the three different classifications of hypodontia and what do they mean
- Hypodontia – the absence of <6
- Oligodontia –the absence of ≥6 teeth
- Anodontia – the absence of all teeth
what are the conditions associated with Hypodontia?
- Cleft lip and palate
- Downs syndrome
- Ectodermal dysplasia
what is Ectodermal dysplasia? what does it cause and which condition of teeth is it associated with?
- a group of genetic disorders which involve defects of the hair, skin, nails, teeth, mucous
membranes and sweat glands. - Derived from the ectoderm
primary germ layer - Associated with Hypodontia
what is the treatment options for Hypodontia?
- Open up the space and add teeth as prosthetics
- Do ortho and close the gap to camouflage the missing teeth
what’s the definition of microdontia
Teeth which have smaller than average dimensions (more than 2 standard deviations) – range from mildly to severely
- Which tooth is mostly affected by microdontia?
- what treatment option is available for it?
- upper lateral (peg-shaped)
Treatment
- 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
Which teeth most commonly affected by macrodontia?
Upper 1s / lower 5s are most commonly affected – often bilateral
What is the treatment option for Macrodontia?
- Accept – generally done if mild or in a less aesthetically challenging area e.g. lower 5s
- Extract and reduce space for a normal-sized prosthesis
- Extract and close the space
- Camouflage restoratively to resemble 2 teeth e.g. if a very large upper 1 and missing upper 2 (crown will be put on top of 1 which has an attached 2)
What is the definition of Fusion?
fusion of 2 separate tooth germs leading to a reduced number of teeth in the arch (it looks like one tooth with a slight split in the middle)
What is the definition of Germination?
Developmental separation of a single tooth germ (one root but crown looks separated)
Are the double teeth more common in primary or secondary dentition? and what is their prevalence from female to male?
- More common in primary (0.5-1.6%) than secondary (0.1-0.2%) dentition and anteriorly
- Female: Male = 1:1
Treatment for double teeth (fusion/germination)?
- No intervention is needed in the primary dentition
- 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
- Extract
What is tooth Invagination?
An enamel lined ‘infolding’ in the crown of a tooth, which can extend into the root
- Upper 2s most commonly affected, followed by upper 1s
What is the management of 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
- 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 is Dilaceration?
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 managment of Dilaceration?
Management
- 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
What is the aetiology of Dilaceration?
Traumatic – due to intrusion of a primary incisor into developing tooth germ
- Position of dilaceration corresponds with the stage of development at the time of trauma
- Generally, crown is angled palatally and hypoplasia was seen at the site of dilaceration
Developmental – may be due to an obstruction of the eruption path
- Generally, crown is angled upward and labially and no hypoplasia is seen
- Upper 1s most commonly affected
what is the time range that by then the bilateral tooth should have erupted?
6-12 months.
If the tooth still has not erupted, Investigate!
Name some systemic conditions associated with delayed eruption
- Cleidocranial Dysostosis
- Down Syndrome
- Cleft Lip and Palate
- Hereditary Gingival Hyperplasia
Name some Local factors associated with delayed eruption
Crowding / Supernumeraries
Trauma / Dilaceration
Ectopic Tooth Germ
Early Loss of Primary Teeth
Retention of Primary Teeth
Local Pathology
Transpositions
What is the difference between Ectopic and Impacted teeth?
- Ectopic – abnormal place or position
- Impacted – physical impediment to eruption by another structure such as bone, adjacent teeth, soft tissues
Aetiology of unerupted teeth
- Polygenic multifactorial
- Genetic theory
o Family history
o frequency bilateral than expected
o Associated malformations - Guidance theory / local factors
o Missing or absent lateral incisor
o Retention of Primary canine
o Crowding
What is the consequence of unerupted teeth?
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
When should we start palpating for canines?
- caNINE= 9 years old
- majority of maxillary canine should be palatable by the age of 10
When is the canine eruption considered to be late?
Considered late if not erupted before 12.3 years in girls and 13.1 years in boys
How long should it be between the eruption of two bilateral canines?
they should erupt within 6 months
When should we consider referrals for unerupted canines?
If not palpatable by the age of 10!
What is Mechanical Failure of Eruption / Ankylosis
- The uncommon, isolated condition causing a localised failure of eruption of a single tooth with
no other identifiable causes - May partially erupt and then appear to submerge due to continued vertical growth of the
rest of the alveolar complex
Management of Ankylosis?
The teeth fail to respond to orthodontic forces – often removal is indicated
What’s the difference between prevalence of Cleft palate compared with cleft lip and palate?
- Cleft lip and palate: more common, 2:1 Male: Female, more common in Asians than Africans
- Cleft Palate: less common and less racial variation, 4:1 Male: Female
What are the key dental findings in Down Syndrome?
- Class III malocclusion - maxillary hypoplasia
- Hypodontia
- CLP
- Microdontia
- Delayed eruption of 2ry dentition
- Short roots
What are the key dental findings in Ectodermal Dysplasia?
- Class III malocclusion
- Anodontia / severe hypodontia
- Deformed teeth / conical crowns
- Delayed eruption
- Xerostomia
- CLP
What are the key dental findings in Cleidocranial Dysostosis?
- Class III malocclusion - Mx hypoplasia
- Multiple supernumerary teeth
- Dentigerous cysts
- Retained 1ry teeth
- Failure of eruption of 2ry teeth
