Dentinogenesis and Inherited Dentin Defects Flashcards
What is Dentin by volume
50% mineral
30% organic matrix
what makes up the Organic matrix of Dentin by weight
90% Collagen
90% of non-collagen is Derived from DSPP (Dentin Sialophosphoportein)
-also: dentin matrix protein, osteonectin, bone sialoprotein, osteopontin, proteoglycans…
what do Odontoblasts differentiate from
Dental papilla cells
A long cytoplasmic extension encased in dentin
Odontoblastic process
Rate of Dentin deposition
4 micrometers per days
How is Dentin deposited as
Incrementally as lines of Owen (or Von ebner)
what does the pulp chamber and root canal shrink in size over life
Dentin formation occures throughout life
layers of the pulp from outisde to insde
Odontoblastic layer
CEll-free zone
Cell-rich zone
Pulper core
what is found in the cell-free zone
Nerve and capillary plexus
what is found in the cell rich zone
Extensive vascular system
how do Lines of Von ebner grow
Grow 1 day at a time horizontal and at a right angle to dentinal tubules
what do Lines of von ebner form
Accentuated lines due to disturbances in mineralization
why is Dentin sensitive
By odontoblast processes
where does more terminal branching of dentin tubules occure
In root dentin (more than in coronal dnetin)
Shape of Dentin tubules in the crown and the root
Crown: S shaped
Root: Strait
size of dentinal tubules
1-3 micrometers in diameter
does the crown or root have more dentin tubules
More in the crown
are there more dnetin tubles near the pulp or the surface
More near the pulp
what is Predentin
The fibrillar organic matrix before its calcification
what is primary dnetin
Dentin made during tooth formation
what type of dentin makes up the tooth
primary dentin
other name for Primary Dnetin
Circumpulpal dentin
the outer layer of primary dnetin
Mantle dentin
when is secondary dentin formed
By the slow continual deposition of dentin by odontoblasts following the completetion of the roots
what happens the change of primary and secondary dentin
tubular structures is continuous but changes direction
why does pulp recession occure
Deposotion of secondary dentin is fastest on the roof and floor of the pulp chamber
why does Tertiary dentin form
Local reaction to attrition, caries, or dental restoration
what determines the architecture (quality) of tertiary dentin
Depends on the intensity and duration of the stimulus
Tubules present in the dentin
Continuous
Sparse
Irregular
Absent
Types of Tertiary dentin
Reactionary Dentin
Reparative Dentin
what formes Reactionary dentin
Preexisting odontoblasts
what forms Reparative dentin
Newly differentiated odontoblast-like cells
When Newly differentiated odontoblast-like cells are included in the dentin
Osteodentin
what is Sclerotic Dentin
Translucent dentin due to calcifaction of the dentinal tubules as a result of injury or aging (also called transparent dentin)
why does Globular mineralization of dentin occur
High rates of Dentin Deposition leading to an irregular mineralization front
why does Linear Mineralization of dentin occur
Slow rates of deposition leadding to more uniform
when globular zones of mineral fail to fuse into a homogeneous mass due to hypomineralized dentin
Interglobular dentin
what is found in interglobular dentin
Dentin tubules pass through but no peritubular dentin is present
dentin that surrounds the dentinal tubules
Peritubular dentin
Organic and innorganic parts of PEritubular dentin
Low in Collagen
Higher in DSPP (Dentin sialophosphoprotein)
higher mineralization than intertubular dentin
HArdness of Intertubular dentin at the DEJ vs Pulp
DEJ is 4x as hard
Peritubular dentin hardness at the DEJ and Pulp
equal
Peritubular dentin vs Intertubular dentin at the pulp
PTD is 20x harder
Peritubular dentin vs Intertubular dentin at the DEJ
PTD is 5x harder
does Dentin or enamel mineralize first
Dentin is first
what is DGI type I
Dental phenotype in persons with Osteogenesis imperfected
what are thy symptomes of DGI type I
Teeth show marked discoloration and attrition in both deciduous and permanent dentition
what happens to the Pulp of DGI type I
Obliterated before or soon after tooth eruption
what mutations cuase osteogenesis imperfected
Mutation in the COL1A1 and COL1A2 genes
how is collagen formed
Two type I collagen alpha 1 chains fold with one alpha 2 chain to form a triple helix
Mutation of COL1A1 and COL1A2 lead to
Reduced Collagen (less severe phenotype) Prduce defective collagen (severe phenotype)
How is Osteogenesis imperfecta passed on
Autosomal-dominant
how does a patient radiograph look when they have DGI
Bulbous crowns
Pulpal obliteration
short roots
Tooth impactions (both upper and second molars)
what mutation causes Dentinogeneisis imperfecta
utation in the dentin sialophosphorportein gene (DSPP)
what cells express DSPP
Preameloblasts, preodontoblasts, ODonotblasts
Strucutural domains of DSPP
DSP-proteoglycan
DPP- acic protein
Isoelectic point of DPP
1.0 (lots of phosphoserines)
mutations of DSPP cause
DD-II, DGI-II, DGI-III
what cleaves DSPP into DSP and DPP
Extracellular proteases
when missing DSPP what is shown in a radiograph
Enlarged pulp cavity
Decreased mineral density
Globular mineralized zones
less mineralized dentin and more predentin
Types of Dentin Dysplasia
DD-I
DD-II
Types of Dentinogenesis imperfecta
DGI-I
DGI-II
DGI-III
where do mutations occure in DSPP to cause dentin defects
5’ splicing
Framshift mutation at the 3’ end (exon 5)
how id Dentinogeneis imperfecta type II different from OI
DGI-II only affects the teeth
Commonness of DGI-II
1 in 6k to 8k
what causes DGI-II
Mutations in DSPP
How do people with DGI-II look
Blue gray, amber brown and opalescent teeth
how do People with DGI-II look in radiographs
Teeth have bulbous crowns, Narrow roots
Pulp chambers and canals are gone or small
what happens to teeth of DGI-II from occlusal stress
Enamel may split from dentin
when was DGI-III found
Brandywine isolate from southern maryland and washing D.C.
how can DGI-III be differentiated from DGI-I and DGI-II
all appeaer similar except for DGI-III can have multiple pulp exposures in deciduous teeth
Radiographs of DGI-III show
Variation in appears (pulpal obliteration, normal, or shell teeth
commonness of Dentin Dysplasia Type I (DD-I)
1 in 100,000
How do the teeth look in DD-I
Both permanent and deciduous teeth are normal shape, form and color
How does DD-I look in a radiograph
Short roots with unusual mobility and early exfoliation
Cresecent shaped pulpal remnant parallel to the CEJ in the permanent dentition and total pulpal obliteration in the deciduous dentition
How does the Teeth look in DD-II
Decidous teeth have deatures of DGI-II
Permanent teeth are normal shape, form, and color
Normal root length
What is found in the pulp cavities of DD-II
Thistle tube deformity
PUlp stones
What causes DGI-II, DGI-III, and DD-II
All about the same disease caused by dominant-negative effects (not haploinsufficiency)
what affects the severity of DSPP mutations
the effect of the DSPP mutation may lead to the different phenotypes (ie if its it DD-II, DGI-II, or DGI-III)
what does DD-II
DGI-II
DGI-III cause
DD-II: partial obliteration, mild discoloration
DGI-II: Pulpal obliteration, Discoloration in both dentitions
DGI-III: pulpal exposure, early abscess
How will dentin dissorders be organized in the future
No DGI-I, become named based on the disease phenotype
DD-II, DGI-II, and DGI-III all called DSPP mutations with considerations to severity
