Dental Anomalies Flashcards
How to approach developmental anomalies?
- Quantity: too many teeth? Too little teeth?
- Size: too big? Too small?
- Shape: is the morphology unusual?
- Aetiology: genetic or environmental?
Q.S.S.A:
“Queering seen situations accurately”
Hypodontia: Anodontia
Total lack of teeth in one or both dentitions
Hypodontia: Oligodontia
Rare condition where more than 6 primary or permanent teeth are absent.
Hypodontia: Prevalence
Primary dentition <1%
Permanent dentition 3-6%
More common in females 4:1
Hypodontia: third molars?
Missing 3rd molars in up to 30% of people.
Hypodontia: most commonly missing teeth
- Wisdom teeth
- lower 1st premolars
- Upper lateral incisors
- Upper 1st premolars
Hypodontia: ___% of patients with missing primary teeth also have missing permanent teeth.
50
Hypodontia: aetiology
Considered likely to be genetic (however could be in combination with environmental insult).
Hypodontia: associated syndromes
Down syndrome (trisomy 21)
Ectodermal dysplasia
Hypodontia: genetic issues
Autosomal dominant inheritance pattern in some families
Mutation in the MSX1 gene on chromosome 4
Ectodermal dysplasia
Occur when the outer layer of tissue (ectoderm) of the embryo does not develop normally.
Oral manifestiations: conical or pegged teeth, hypodontia or complete anodontia and delayed eruption of permanent teeth.
Other major symptoms: fewer sweat glands, putting infants at risks at overheating.
Age of this patient? Caries risk of this patient?
8-9 years old
6s present; over 6 years old.
7s furcations developing.
Lower 3s coming in = 9 years.
High caries risk; look at lower left 6 distal cusp (would consider extracting this tooth if 5 was present) and upper left 6 distal cusp. Overcrowding on upper left hand side liaise with orthodontist consultant.
What’s missing here?
Complex Hypodontia case, teeth missing:
Two upper lateral incisors.
One lower central incisor.
Lower right 5.
Upper left 5.
Where is caries present?
Lower right 6
Upper left 6
Lower left 6
Supernumerary teeth: prevalence
Primary dentition: 0.2-0.8%
Permanent dentition: 1.5-3.5%
Anterior maxilla most common site
Supernumerary teeth: associated conditions
Cleft lip and palate (40% of cases)
Cleidocranial dysostosis
Supernumerary teeth: mesiodens
In the midline; usually peg shaped teeth
Supernumerary teeth: supplemental teeth
Look like a normal tooth
Supernumerary teeth: Conical supernumeraries
If not inverted, there is a good chance they will erupt.
If not impeding eruption of other teeth, can be monitored until erupted and then extracted.
If inverted, they may migrate superiority towards nose.
Supernumerary teeth: Tuberculate supernumaries
Don’t tend to migrate but may impede eruption of adjacent teeth
Cleidocranial dysostosis
- The collar bones may be missing or abnormally developed.
- Delayed exfoliation, delayed or failing eruption of the permanent dentition with multiple supernumerary teeth, protruding mandible, and mid-face retrusion.
What are key considerations with unusual eruption patterns?
- Correct sequence of eruption
- Symmetry (if one tooth has come in and the other hasn’t, after 6 months - there would be concern).
What kind of supernumary teeth are these?
Conical (mesiodens - in the midline)
Where is this supernumerary tooth located (palatal or labial)?
Palatal (because as the X-ray tube has moved to take the other view of the tooth, the tooth appears to be going up the way)
Locate this supernumerary tooth.
Palatal (“x-ray tube has moved with the tooth”)
Where is the supernumerary tooth on this radiograph and what kind of tooth is it (how might this impact clinically)?
Inverted supernumerary tooth (upside down: wants to move in the direction of the arrow).
Clinical implications means this tooth will not erupt.
Microdontia: peg shaped teeth
Peg shaped laterals
Microdontia: Prevalence
Primary teeth: 0.2-0.5%
Permanent teeth: 2.5%
More common in females than males
Lateral incisors most affected
Macrodontia: how can you tell if a tooth is fusion or gemination?
Clincally: Count the teeth !
Gemination: one extra crown in the mouth.
Fusion or gemination?
Fusion
Fusion or gemination?
Fusion
Fusion or gemination?
Gemination
Talon cusp
Think of it as the opposite of an invagination. It may have its own bit of pulp! Don’t be tempted to lift the high speed to smooth down. Can be mistaken for supernumerary when partially erupted.
Amelogenesis imperfecta
A spectrum of hereditary defects in the function of ameloblasts and mineralisation of enamel matrix.
Amelogenesis imperfecta: classifications
- Hypoplastic type: think, but hard enamel; normal bond strength.
- Hypomineralised type: full thickness enamel, but very soft; impaired bond strength.
NOTE: If a disturbance occurs during the secretion phase, the enamel defect is called hypoplasia. If it occurs during the mineralisation or maturation phase, it is called hypomineralisation.
Amelogenesis imperfecta: prevalence
1:700-4000
Amelogenesis imperfecta: inheritance
- Autosomal dominant
- Autosomal recessive
- X-linked
- Sporadic inheritance patterns
- As well as sporadic cases
Amelogenesis imperfecta: other oral manifestations
- Pulp calcification
- Taurodontism
- Delayed eruption
- Gingival overgrowth
- Skeletal anterior open bite (~50% of patients)
Amelogenesis imperfecta: hypomaturation
Case: half brother has as well. Different fathers, type ..?
X-linked
Hypoplastic or hypomineralised?
Can’t tell as enamel is breaking down
Hypomineralised or Hypoplastic?
Hypomineralised (i.e breakdown occurs after eruption)
Looking at the 5s, the are the correct shape until they’ve erupted.
Dentinogenesis imperfecta: Type I
Associated with osteogenesis imperfecta.
Dentinogenesis imperfecta: Type II
Dentinogenesis imperfecta on its own, more significant that type I but doesn’t involve osteogenesis.
Dentinogenesis imperfecta: Type III
“Brandywine isolate” very rare (1:8000)
Features of a patient with dentinogenesis imperfecta
Likelihood of skeletal abnormalities.
>70% class III skeletal pattern
Likelihood of bone fractures.
Biphosphanates routinely used in management.
Cardiac defects likely.
Dentinogenesis: Features in primary dentition
Colour - amber
Attrition
Pulp obliteration
Spontaneous abscesses
Dentinogenesis: permanent dentition
Colour - grey/translucent
Short roots
Pulp obliteration
Spontaneous abscesses
Main clinical problems with a patient with Dentinogenesis imperfecta
- Poor aesthetics
- Chipping & attrition of enamel
- Exposure of dentine
- Poor oral hygiene, gingivitis and caries
- Pain and infection, pupal necrosis
Molar incisor hypomineralisation (MIH)
Developmental defect in enamel structure
Typically primarily first permanent molars and central incisors.
1 in 5 people (very common)
MIH: aetiology
Not fully understood…
1. Environmental factors during late preganancy or first year of life
2. Genetic component
Fluorosis
- Result from ingestion of high F concentrations during Amelogenesis
- Irregular enamel opacities, stained if severe
- Only affects teeth being form during time of excessive fluoride
NOTE: unusual in Scotland
Turner’s tooth
- Affects successional tooth (often second premolars)
- Allegedly Hypoplastic enamel following infection around the interradicular area of a primary tooth
- But how many sinuses abscesses on primary molars result in this appearance.
Dilaceration of root
As a result of trauma to the tooth germ, during root formation.
Case: primary tooth gets knocked, this hits the permanent tooth germ and as a result the permanent tooth’s root begins growing in an odd direction.
Metabolic disturbances
Presence of certain ion during Amelogenesis resulting in colour change. Can often results in banding effect.
Discuss the clinical problems seen in this case.
Red - supernumerary tooth (supplemental)
Blue - Invagination on the lateral incisors (possibly dens in dente)
Green - very poor oral hygiene (not to be confused with MIH)
When do primary teeth start to erupt?
6 months
Which primary teeth erupt first?
lower central incisors
When is the primary dentition complete?
Around 2.5 years
When does the mixed dentition stage begin?
6 years
Which teeth erupt first in mixed dentition stage?
Lower central incisors
What are the 2 main phases of the mixed dentition stage?
Between 6-8
And
Between 10-12
When is the permanent dentition established and what are the main features of this?
Around 12 years
Molar relationship. no crowding or spacing or rotated teeth. Occlusal plane flat or mild curve of Spee
Curve of Spee
The curvature of the mandibular occlusal plane.
When do primary teeth develop?
28 days in utero: continuous dental epithelium arrives
~6 weeks in utero: Signalling initiated the dental
dilacerated teeth are most commonly causes by…
trauma to the primary predecessor tooth
Dens evaginatus
What is dens evaginatus?
Outer surface appears to form an extra bump or cusp (commonly affects premolars) —> Mongoloid origin.
What can you see radiographically with dentinogenesis imperfecta?
Roots are shorter and may be more pointed than usual.
What is the incisor liability?
Difference in mesiodistal width of the primary and secondary incisors.
