Inherited Dental Anomalies Flashcards
Enamel Defects
Amelogenesis imperfecta
Molar-incisor hypomineralisation
Dentine Defects
Dentinogenesis imperfecta
Dentinal Dysplasia
How does enamel develop? (2 phases)
1st phase: organic matrix which is laid by ameloblasts, this is the scaffolding of the tooth which gives enamel it’s shape
2nd phase: mineralisation
Enamel Hypoplasia
Disturbance in the formation of the matrix which results in thin, pitted or grooved enamel
Hypomineralisation
- Disturbance of mineralisation of the matrix
- Discoloured (yellow/brown)
- Opaque enamel
- Affected enamel weak, prone to breakdown
- Supersensitive teeth
Amelogenesis imperfecta
- Incidence 1:700 - 1:14,000
- Affects all or nearly all the teeth more or less equally
- Genetic developmental anomaly of enamel
- Affects the structure and clinical appearance of enamel
- Some phenotypes are less obvious in primary dentition (permanent dentition can be more affected than primary)
- Autosomal dominant/autosomal recessive/x-linked/sporadic
- X-linked: affects more males than females, affects enamelin gene on chromosome 4
Amelogenesis imperfecta clinical features
- Yellow brown discolouration
- Primary and permanent
- Generalised
- Delayed eruption
- Microdontia
- Post eruptive breakdown
- Severe attrition
- Sensitivity
- Gingival enlargement
- Associated with anterior open bite
Amelogenesis imperfecta phenotype classification
- Hypoplastic: pitted, vertical ridges, generalised hypoplasia
- Hypomineralised: hypocalcified (most common form), enamel is soft & hypomaturation: white opaque +/- brown spots
- Hypoplastic + hypomineralised
Radiographic features of amelogenesis imperfecta
Enamel thin (hypoplastic) or less dense (hypomineralised) Contact points lost
Dentinogenesis imperfecta
- Hereditary disorder affecting dentine structure
- Type 1: occurs with OI + collagen defect, incidence of OI is approx. 6-7:100,000, mutations of the 2 collagen type 1 genes on chromosome 7 or 17
- Type 2: 1:6,000 or 1: 8,000 autosomal dominant, usually die before birth, occurs without OI
- Type 3: rare, Brandywine isolate
Dentinogenesis imperfecta type 1 clinical features
- Osteogenesis imperfecta
- Sclera blue hue
- Teeth amber/grey/blue hue
- Translucent teeth
- Spontaneous abscesses
- Attrition
- Less obvious in permanent dentition
- Expressivity variable
Dentinogenesis imperfecta type 2 clinical features + radiographic features
- Amber/brown or grey/blue hue
- Enamel normal
- Both dentitions affected
- +/- hearing loss
- Mutation in the sialophosphoprotein gene
Radiographic features:
Bulbous crowns, marked cervical constriction, short roots, pulp obliteration and radiolucent areas without caries
Dentinogenesis imperfecta type 3 radiographic features
DI type 3 = brandywine isolate/hereditary opalescent dentine which is found in isolated racial/family group, similar to type 1 and 2 DI.
Primary teeth: multiple pulp exposures and “shell” teeth
Dentinal dysplasia classification
Dentinal dysplasia: rare genetic developmental abnormality of dentine structure. Affects primary and permanent dentition.
Type 1: radicular dyplasia - “rootless teeth”, incidence 1:100,000
Type 2: coronal dysplasia, probably an allele of dentinogenesis imperfecta
Dentinal dysplasia type 1 radicular dysplasia clinical features
Coronal dentine dysplasia
- Rootless teeth
- Normal crown morphology
- Amber discolouration
- Premature exfoliation due to stunted roots
- Poorly aligned teeth
- Pulp obliteration
- Short blunt roots
- Dental abscess/cysts 20%
