Unit 11 - Dentin and Pulp Flashcards
Resistance of a material to breaking under pressure
Tensile strength
Chemical characteristics of dentin
70% inorganic
20% organic
10% water
Is dentin harder than bone?
Yes
Is dentin vascular?
No
Three types of dentin
Primary
Secondary
Tertiary
When does dentinogenesis begin?
In the late bell stage of tooth development
Describe dentinogenesis
Odontoblasts orginate from neural crest cells of the papilla. Odontoblasts are introduced by the inner enamel epithelial cells in the crown and hertwig’s epithelial cells on the root.
Collagen fibrils in the first layer of the dentin matrix are course in texture and are laid
Perpendicular to the DEJ
What are the collagen fibrils in the first layer that are laid perpendicular to the DEJ called?
Von Kroff’s fibers
Collagen fibers in the remaining layers are
Finer and run paralell to the DEJ
Uncalcified matrix is referred to as
Predentin
During matrix production phase, unmineralized dentin remains present adjacent to the
Odontoblasts
During dentin’s first phase of maturation, a membrane bound vesicle is deposited in the matrix. This vesicle contains
Several hydroxyappetite crystals
Describe the first phase of maturation for dentin development
A membrane bound vesicle is deposited in the maxtrix. This vesicle contains several hydroxyappetite crystals.
The crystals is the vesicle will grow until large enough to rupture the membrane
Many growing crystals will coalesce with one another obsurcing the matrix
Gradually the crystals fuse to each other until the dentin is fully mineralized
Describe the second phase of maturation during dentin development
New areas of crystal formation appear and expand but do not fuse completely to each other
The globules of mineralizing dentin remain visible in the predentin/dentin border
Mineralization process is now complete. Fusion during the secondary mineralization phase results in microscopic differences
Areas of complete crystaline fusion of dentin are refered to as
Globular dentin
Areas of incomplete fusion of globules of dentin are referred to as
Interglobular dentin
Dentinal tubules extend through the dentin from DEJ to pulp in an _______ shape
S
The tubules provide the space in which the _______________ is housed
Odontoblast process
Odontoblastic processes are responsible for
Maintaining and repairing dentin after the caries process and dental restorative procedures
The tubules are crowded at the ______ surfaces
Occulsal or incisal
What runs off from the tubles to inter-connect tubles?
Lateral extensions
What results in the permeability quality of dentin?
Dentinal tubules
Type of dentin that appears as a bright halo, hypermineralized, region between the tubules is a less mineralized region.
Peritubular
Type of dentin that appears between the tubules and is the majority of dentin. It is less calcified than peritubular.
Intertubular
The outermost layer of dentin and the root is mostly made up of this type of dentin
Mantle
The term used to describe an area of dentin
Circumpulpal
Dentin formed before the apical foramen was complete
Primary
Dentin formed after the apical formaen due to everyday stimuli
Secondary
Dentin formed in response to trauma
Tertiary
Formed during rythmic active and quiet phases which makes a difference appearance of layers. The lines run at right angles to the tubules
Incrimental Lines of Von Ebner
This results from an illness or metabolic disturbance and is a band of dentin that is slightly different in composition from the rest of dentin layers.
Contour Lines of Owen
These are islands of non-calcified dentin. Located in the surface layer of cementum in root dentin.
Tomes granular layer
In aging dentin, the diameter narrows tubule narrows because of
Deposition of peritubular dentin
When the tubules are completely calcified it is referred to as
Sclerotic dentin
Functions of pulp
Support
Sensory
Nutritive
Protective
Pulp anatomy: apical foramen size
0.3 - 0.6 mm diameter
What happens to the apical foramen with age?
Reduces in size due to cementum and dentin gradually depositing
Extra canals which develop where the Hertwig’s Epithelial Root Sheath was interrupted by blood vessels passing through it.
Accessory canals
Removal of pulp chamber and pulp horns
Pulpectomy
Removal of the pulp horns only
Pulpotomy
Removal of the coronal and radicular pulp
Endodontic therapy (RCT)
Calcified bodies in pulp that can form with the pulp or with age or if the pulp becomes ill
Pulp stones or denticles
What is microscopically seen that the deposits resemble dentin by exhibiting tubules and a process? They are formed with the tooth often in the root canals but can also be in the center of the pulp
True denticles
What are the three types of denticles?
True Denticles
False Denticles
Diffuse/embedded Calcifications
What type of denticle is formed with age, usually in the coronal pulp and formed with minerals around debris in the pulpal tissue?
False denticles
How are false denticles viewed under microscope?
Irregular concentric layers of a calcified matrix
What type of denticle forms due to an ill pulp inducing spontaneous calcifications in a number of locations?
Diffuse/embedded denticles
How are diffuse/embedded denticles viewed under a microscope?
Same as false denticles in structure and usually seen in the root
