Exam 2 Flashcards
Percentages of dentin:
Mineral: ?
Organic: ?
Water: ?
Mineral: 70%
Organic: 20%
Water: 10%
How does Type 1 Collagen of dentin differ than that in bone?
- higher ratio of proline and hydroxyproline
- Higher prevalence of molec crosslinking
- more bound to water
What structure located in what part of the enamel organ stimulates osteoblast differentiation?
fibronectin in the basal lamina of inner enamel epithelium
What are the four growth factors secreted by the IEE?
- Transforming Growth Factor (TGF)
- Bone Morphogenetic Protein (BMP)
- Insulin-like Growth Factor (IGF)
- Fibroblast Growth Factor (FGF)
How thick is mantle dentin?
50-100 micrometers
What are lines of von Ebner?
hesitation in matrix formation every 4-20 days that show has hypomineralization of dentin
Dentin tubule diameter at pulpal surface vs the DEJ?
Pulpal surface: 2.5 micrometers
DEJ: 0.9 micrometers
What is bad about interglobular dentin? Where is it often found?
- nothing wrong, formed by hypomineralized area in between normal areas
- in dentin in crowns
What is Tome’s Granular Layer?
-granular appearing layer of dentin adjacent to cementum
Define primary and secondary dentin
Primary: dentin (except mantle dentin) formed up to the time of functional occlusion
Secondary: dentin (except tertiary dentin) formed after tooth achieves functional occlusion
Where does tertiary/reparative dentin come from?
-subodontoblastic layer
Where do the growth factors that affect the subodontoblastic layer come from?
the pulp
What condition lead to bluish opalescent teeth with normal enamel?
Dentinogenesis imperfecta
What condition can lead to teeth having no pulp chambers?
Dentinogenesis imperfecta
What does fluoride replace in hydroxyapatite crystals?
hydroxyl ions
What are the 5 bacteria thought to be responsible for caries?
- Streptococcus mutans
- Streptococcus sorbrinus
- Streptococcus gordonii
- Lactobacillus acidophilus
- Actinomyces viscosus (root caries)
What teeth are most commonly affected by dentinal sensitivity?
Canines and premolars
The Brannstrom’s Hydrodynamic Theory of dentin sensitivity is based on what law of physics?
Charles’ Law (volume of gas or liquid is directly proportional to heat applied at constant pressure
At what stage of tooth development does pulp start forming?
Cap Stage
When do capillaries start developing in the pulp?
Bell Stage
What is the origin of pulpal cells?
Ectomesenchymal neural crest cells
What are the two compartments of the pulp?
What is in each compartment?
- Odontogenic Zone: odontoblast cell layer, cell-free zone of Weil, Cell-rich zone, parietal plexus of nerves (Raschkow’s plexus)
- Pulpal Core: Fibroblasts, Type I and II collagen, extracellular matrix, blood vessels, nerve tissue
What are the functions of dental pulp?
Embryonic induction, formative, protective, reparative
What are the non-collagenous matrix components of pulp?
- proteoglycans
- glycosaminoglycans
- phosphoproteins
- glycoproteins
- gamma-carboxyglutamate-containing proteins
What CN branch innervates the pulp? (sensory and motor)
CN V (Trigeminal)
What are the classifications of the sensory nerve fibers ni the pulp?
- fast: A-delta for sharp pain, large diameter
- slow: C for dull pain, narrow diameter
How many branches does each nerve fiber contribute to Raschkow’s Plexus?
at least 8
A majority of nerve axons are in the ______ of the pulp horns, remaining crown, and root.
predentin
Part of tooth with least amount of blood vessel branching
root apex
Do pulp venules or arterioles have a larger lumen?
Venules (100-150)
Arterioles (50-100)
Why might pulp die due to age?
Pulpal hypoxia due to bood deprivation caused by cholesterol plaques in bv
What two things cause pulpal fibrosis?
Increasing age or persistent low-grade inuury like multiple restorations, bruxism, or repeated thermal insult
Why might someone have calcified deposits along collagen fiber bundles or in blood vessels in the pulp?
Chronic low grade inflammation can cause diffuse calcifications
Difference between true and false denticles
True has dentin tubules. False don’t have tubules and have concentric layers of calcified tissue.
Where might you see vacuolated or syncytial macrophages?
In a dental abscess.
If pulpal necrosis expands to the alveolar bone then to muscle tissue, what condition may occur?
Diffuse cellulitis
Functions of the GFL: 5 of them
PAPAI
- provide rigidity to marginal gingiva
- act as periosteum for interproximal crestal alveolar bone
- provide 1/2 of biologic width
- act as protective barrier to spread of gingival inflammation
- inhibit apical migration of junctional epithelium
What is the biologic width?
Area of junctional epithelium and gingival fiber attachment to the root of the tooth. Violation of this width due to overextended margins will cause chronic inflammation and alveolar bone loss to restore 2mm required width
What are the 5 functions of the PDL?
- Supportive
- Regenerative (self, and helps w/ cementum and bone repair)
- Nutritional (via blood vessels)
- Sensory
- Protective (cushions tooth)
What are the 5 functions of the PDL?
- Supportive
- Regenerative (self, and helps w/ cementum and bone repair)
- Nutritional (via blood vessels)
- Sensory
- Protective (cushions tooth)
During tooth development, the PDL comes from ____ which is derived from _____ _____ cells.
- the dental follicle
- neural crest
The three layers of the dental follicle make what three PDL associated structures?
Outer Zone: Alveolar bone
Intermediate Zone: PDL
Inner Zone: cementum
What two groups of PDL fibers appear to form first in development?
DGF and DPF
What are principle fibers?
Collagen fibers that are embedded into the cementum. (Sharpey’s Fibers)
What supports the principle fibers?
Indifferent fiber plexus
Would interradicular fibers be found in anterior teeth?
No (unless there was a multirooted tooth)
What fibers are responsible for orthodontic relapse?
- Transseptal
- Semicircular
- PDL principle fiber groups
What is found in the interstitial spaces of the PDL?
- blood vessels
- undifferentiated cells
If an injury is significant enough to involve alveolar bone? How does it repair?
Akylosis due to vascular bone being the primary repair mechanism. If the interstitial spaces are not injured, then the PDL can repair itself.
If an injury is significant enough to involve alveolar bone? How does it repair?
Akylosis due to vascular bone being the primary repair mechanism. If the interstitial spaces are not injured, then the PDL can repair itself.
Why is a membrane needed to stimulate proper healing of bone loss?
Prevents migration of epithelial tissue from gingiva. Allows differentiation of mesenchymal cells in interstitial spaces of PDL and marrow spaces of adjacent alveolar bone
What is the origin of the epithelial rests of malassez?
Hertwig’s Rooth Sheath
Lateral periodontal cysts are thought to come from….
epithelial rests of mallesez
Gingival cysts are derived from _________ rests of ________. And are remnants of the ______ _______.
- epithelial rests of serres
- dental lamina
What is the average width of the PDL in an adult?
about 0.17 mm
What is more similar in organic vs mineral composition? Dentin and bone or cementum and bone?
Dentin and bone have similar composition. Cementum is about 50:50 organic and mineral
How much thicker is cementum at the apex than at midroot?
twice as thick at the apex
What layer of the dental follicle leads to the cementum?
Inner
What causes differentiation of the undifferentiated mesenchymal cells in the follicle to turn into cementoblasts?
Perforations in Hertwig’s Root Sheath allow those cells to contact the dentin where dentin growth factors stimulate differentiation.
How are cementocytes and osteocytes similar?
Both have lacunae and canaliculi
Percentages of CEJ overlap, end-to-end, and gap.
Overlap: 60%
E2E: 30%
Gap: 10%
Difference between abrasion and erosion?
Abrasion is due to friction and erosion is due to chemical wear
Where can cementicles be found?
Calcified bodies similar to denticles. Can be found in cementum or PDL
What is bad about exposed cementum?
- it becomes hypermineralized so PDL collagen cannot reattach.
- facilitates attachment of biofilm
What area of the root is most affected by hypercementosis?
apical 1/3
Where is the most likely place to see accessory root canals in multirooted and then single rooted teeth?
Multirooted: 28% at furcation
Single: 17% at apex (8.8% in middle, 1.6% in coronal portion of root)
