Download Dentinogenesis imperfecta type II

ORAL HISTOLOGY ASSIGNMENT
Submitted By;
Derimol Denny
Roll no: 19
Developmental disturbances means an
abnormality where the pathology starts in the
embryonic stage of human life, before the
formation of the dentition.
Developmental disturbances in teeth are of 5
types based on the feature of the tooth they
affect:
Size of Teeth
Shape of Teeth
Number of Teeth
Structure of Teeth
Growth (Eruption) of Teeth
Here we discussing about developmental
disturbances by structure of teeth.
AFFECTING THE STRUCTURE
1.Amelogenesis Imperfecta
2.Environmental Enamel Hypoplasia
3.Dentinogenesis Imperfecta
4.Dentin Dysplasia
5.Regional Odontodysplasia
6.Dentin Hypocalcification
AMELOGENESIS IMPERFECTA
Amelogenesis imperfecta presents with abnormal formation
of the enamel[1] or external layer of teeth. Enamel is
composed mostly of mineral, that is formed and regulated by
the proteins in it. Amelogenesis imperfecta is due to the
malfunction of the proteins in the enamel: ameloblastin,
enamelin, tuftelin and amelogenin.
People afflicted with amelogenesis imperfecta have teeth
with abnormal color: yellow, brown or grey. The teeth have a
higher risk for dental cavities and are hypersensitive to
temperature changes. This disorder can afflict any number of
teeth
.
Amelogenesis imperfecta can have different inheritance patterns
depending on the gene that is altered. Most cases are caused by
mutations in the ENAM gene and are inherited in an autosomal
dominant pattern. This type of inheritance means one copy of the
altered gene in each cell is sufficient to cause the disorder.
Amelogenesis imperfecta is also inherited in an autosomal recessive
pattern; this form of the disorder can result from mutations in the
ENAM or MMP20 gene. Autosomal recessive inheritance means two
copies of the gene in each cell are altered.
General Information
• Classification can be impractical for
clinicians
• Problems arise in one or more of the
three stages
of enamel formation
– Elaboration of enamel matrix;
hypoplastic
– Mineralization; hypocalcified
– Maturation; hypomaturation
General Information
• Absence of systemic disorder
• Can be part of a syndrome
• Many types
• Different modes of inheritance
• Different phenotypes in a single
family
• Same phenotype with different
gene mutations
• Homozygotes differ from
heterozygotes
• 1:800 – 1:15,000 (clustering)
• Both dentitions
Genes and Phenotypes
• AMELX (amelogenin)
– X-linked
– Diffuse smooth hypoplastic and
hypomaturation
• ENAM (enamelin)
– AD, AR
– Generalized pitting and thin enamel
• MMP-20 (enamelysin)
– AR pigmented hypomaturation
• KLK4 (kallikrein-4)
– hypomaturation
• DLX3 (genes of craniofacial development)
– Hypoplastic/hypomaturation and
taurodontism
• AMBN (ameloblastin)
– Indication for strong association
Hypoplastic type
• Inadequate deposition of organic
matrix
• Normal mineralization
• Radiographic contrast
• Seven types
Treatment
X-ray showing lack of enamel opacity and a pathological loss of
enamel in patient with amelogenesis imperfecta
Crowns are sometimes being used to compensate for the soft
enamel.Usually stainless steel crowns are used in children which
may be replaced by porcelain once they reach adulthood. In the
worst case scenario, the teeth may have to be extracted and
implants or dentures are required.
Dentinogenesis imperfecta
Dentinogenesis imperfecta (hereditary Opalescent
Dentin) is a genetic disorder of tooth development.
This condition causes teeth to be discolored (most
often a blue-gray or yellow-brown color) and
translucent. Teeth are also weaker than normal,
making them prone to rapid wear, breakage, and loss.
These problems can affect both primary (baby) teeth
and permanent teeth. This condition is inherited in
an autosomal dominant pattern, which means one
copy of the altered gene in each cell is sufficient to
cause the disorder. Dentinogenesis imperfecta affects
an estimated 1 in 6,000 to 8,000 people.
Types:
Types of dentinogenesis imperfecta with similar dental
formalities usually an autosomal dominant trait with
variable expressivity but can be recessive if the associated
osteogenesis imperfecta is of recessive type. This is type l.
Type II : Occurs in people without other inherited disorders
(i.e. Osteogenesis imperfecta).It is an autosomal dominant
trait. A few families with type II have progressive hearing
loss in addition to dental abnormalities.
Mutations in the DSPP gene have been identified in
people with type II and type III dentinogenesis imperfecta.
Type I occurs as part of osteogenesis imperfecta.
Dentinogenesis
imperfecta type I
Dentinogenesis imperfecta type I
Individuals with DGI-I also have osteogenesis
imperfecta. The teeth of both dentitions are
typically amber and translucent and show
significant attrition. Radiographically, the teeth
have short, constricted roots and dentine
hypertrophy leading to pulpal obliteration either
before or just after eruption. Expressivity is
variable even within an individual, with some
teeth showing total pulpal obliteration while in
others the dentine appears normal.
Dentinogenesis imperfecta
type II
The dental features of DGI-II are
similar to those of DGI-I but
penetrance is virtually complete
and osteogenesis imperfecta is not
a feature. Bulbous crowns are a
typical feature with marked
cervical constriction. Normal teeth
are never found in DGI-II.
Sensorineural hearing loss has
also been reported as a rare
feature of the condition [5].
Dentinogenesis imperfecta type III
This is a form of DGI found in a tri-racial
population from Maryland and Washington
DC known as the Brandywine isolate. The
clinical features are variable and resemble
those seen in DGI-I and -II but the
primary teeth show multiple pulp
exposures and radiographically, they often
manifest "shell" teeth i.e. teeth which
appear hollow due to hypotrophy of the
dentine.
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