Dentin (Exam II) Flashcards
Dentin is ____ % mineral, ____ % organic, ____ % water
70% mineral
20% organic
10% water
The mineral components of dentin include:
Calcium hydroxyapatite
Trace amounts of calcium carbonate, fluoride, magnesium & zinc
What type of collagen is found in the organic component of dentin?
Type I collagen & trace amounts of type III & V
50% of the noncollagenous proteins in the organic component of dentin are:
phosphoprotein
Sialoprotein, sialophosphoprotein, proteoglycans, glycosaminoglycans, osteonectin & osteopontin are all part of the _____ structural component of dentin
Organic
The type I collagen of dentin is slightly different that of bone, because:
- Higher ratio of ____ & ____
- Higher prevalence of ___
- Higher level of _____
- Random orientation of the _____
- Proline & hydroxyproline
- Molecular cross-linking
- Bound water
- Hydroxyapatite crystals
The non-collagenous dentin matrix proteins include: (5)
- Proteoglycans
- Glycosaminoglycans
- Carboxy-glutamate-containing protein (Gla-proteins)
- Osteonectin
- Osteopontin
The dentin matrix non-collagenous proteoglycans include: (2)
- Biglycan
- Decorin
The dentin matrix non-collagenous glycosaminoglycans include: (2)
Chondroitin-4 sulfate
Chondroitin-6 sulfate
Life stages of the odontoblast include:
- Pre-odontoblast
- Secretory odontoblast
- Transitional odontoblast
- Resting odontoblast
What is the precursor to pre-odontoblasts?
Ectomesenchymal cells
The stimulus for ectomesenchymal cell differentiation to pre-odontoblasts appears to be derived from _____ located within the basal lamina of the inner enamel epithelium (IEE)
Fibronectin
Several growth factors of the pre-odontoblasts are derived from the:
IEE (inner enamel epithelium)
Causes all the cells to align themselves along the basal lamina, assume polarity & differentiate into secretory cells
Pre-odontoblast fibronectin receptors
Growth factors secreted by the IEE that play a role in odontoblast differentiation include:
- Transforming growth factors (TGF)
- Bone morphogenetic proteins (BMP)
- Insulin-like growth factor (IGF)
- Fibroblast growth factor (FGF)
Complete differentiation requires the cell to divide multiple times which allows the cells to express the appropriate receptors able to to bind ____ localized to the IEE basal lamina:
Growth factors
In odontoblast differentiation, the last mitotic division results in a mature odontoblast & a daughter cell that is forced into the ____ cell layer
Subodontoblastic
Cells in the subodontoblastic layer, because they are removed from the sphere of influence of the IEE, represent ______
Ectomesenchymal cells
The ectomesenchymal cells in the subodontoblastic layer are exposed to the entire cascade of developmental controls for _____
Odontoblastic differentiation
What control of odontoblastic differentiation are the ectomesenchymal cells not exposed to?
Inductive influence of growth factors associated with IEE
It is thought that this cell population is responsible for the reparative odontoblast that differentiate from pulpal cells:
Ectomesenchymal cells
The matrix vesicles of the secretory odontoblasts contain everything you need to harden & crystalize the:
Enamel matrix
The secretory odontoblasts are ____ cells with extensive junctional complexes & gap junction formations:
Tall columnar cells
The secretory odontoblasts exhibit significant ______ activity
Alkaline phosphatase
The secretory odontoblasts secrete what types of collagen?
Mainly type I & traces of type III & V
The secretory odontoblasts secrete what matrix vesicles: (7)
- Phospholipids
- Alkaline phosphatase
- Phosphoproteins
- Pyrophosphatase
- Calcium & phosphate
- Annexin
- Calcium hydroxyapatite crystallites
Matrix vesicle secreted by the secretory odontoblasts that is responsible for mediating the flow of calcium into the matrix vesicle & also serves as a collagen receptors that binds matrix vesicles to collagen:
Annexin
50-100 micrometers thick layer of first formed dentin
Mantle dentin
Mantle dentin matrix consists of what type of collagen?
Type I & III
Describe the arrangement of collagen fibers in the matrix of mantle dentin:
Arranged perpendicular to basal lamina in the IEE
The organic matrix of dentin is deposited:
Incrementally
What is the rate of the incremental deposition of the organic matrix of dentin?
4 to 8 micrometers per 24 hours
Incremental lines in dentin (hypomineralized areas) are thought to represent a hesitation in matrix & subsequently altered mineralization that occurs after 4-20 days of matrix deposition
Lines of Von Ebner
Deficiencies & irregularities in _____ result in areas of hypomineralization, commonly appear as accentuated incremental lines for areas of interglobular dentin
Dentinogenesis
Give two examples of deficiencies or irregularities in dentinogenesis resulting in hypomineralization
- Neonatal line
- Contour lines of Owen
Dentin tubules are tapered and are wider at the _____ and narrower at the ____
Pulpal surface
DEJ
Because of the decrease in ______ of the ___ chamber, the number of dentinal tubules per unit area at the pulpal surface is twice as many compared to at the DEJ
Volume; pulp
wWhat has more dentinal tubules per unit area-
Pulpal surface or DEJ?
Twice as many at pulpal surface compared to DEJ
The more calcified, more resistant to etch dentin
Peritubular dentin
Dentin between the dentin
Demineralized intertubular dentin
As you get closer to the basal lamina (to the basement membrane) the processes of the cell tend to branch to increase surface area for more attachment points:
Anastomosis of dentin
Pattern of mineralization in which everything is calcified uniformly
Linear mineralization
They zone of globular rather linear formed dentin seen in the crowns of teeth & root surfaces
Interglobular dentin
Interglobular dentin is characterized by _____ that are unmineralized or hypomineralized dentin between the normal calcified dentinal layers
interglobular spaces
What are the two methods of mineralization we see in dentin?
Linear & globular
A granular-appearing layer in the dentin of the root adjacent to the cementum. Possibly comprised of hypomineralized interglobular dentin:
Tome’s granular layer
All the dentin (except mantle dentin) formed up to the time the tooth achieves functional occlusion
Primary dentin
All the dentin formed (except tertiary dentin) after tooth achieves functinoal occlusion
Secondary dentin
Dentin tubules that are void of the odontoblastic process. They are generally filled with air or organic debris and look black in transmitted light microscopy
Dead tracts
Dentin in which the tubules are occluded with mineral. The dentin is non-tubular and is nearly transparent. Incidence of occurrence increases with increasing age of the patient. May also be tertiary (reparative) dentin:
Sclerotic dentin
The organic matrix is deposited in increments of 4-8 micrometers per 24 hours
Incremental lines of Von Ebner
Occur after 4-20 days of matrix deposition and are thought to represent hesitations in matrix deposition & therefore altered mineralization:
Lines of Von Ebner
Exaggerated lines of von Ebner that occur during periods of altered cell metabolism:
Neonatal Line & Contour lines of Owen
Dentin deposited by newly differentiated odontoblasts at the site of pulpal trauma. A defensive reaction attempting to wall off the pulp from the suite of injury:
Tertiary dentin (reparative dentin)
Cells in the subodontoblastic layer, once exposed to ______ released by stimulated pulpal cells differentiated and form the matrix of ______
Growth factors
Matrix of reparative dentin
The growth factors released by stimulated pulpal cells that form the matrix of reparative dentin after exposure to the cells in the subodontoblastic layers
- Bone morphogenic protein (BMP)
- Insulin-like growth factor (IFG)
- Fibroblast growth factor (FGF)
- Dentin matrix protein (DMP)
Hereditary defect that results in bluish-gray teeth with an opalescent sheen. The enamel is normal but chips off due to lack of support by the abnormal dentin. The pulp chamber & canals are generally obliterated by the defective dentin formation:
Dentinogenesis imperfecta
What important protein is missing when looking at the DEJ in patients with dentinogenesis imperfecta:
Tuftelin
When looking at the teeth through X-ray of a patient with dentinogenesis imperfecta, you can see that:
Pulp chambers are completely obliterated
Loss by wear of surface caused by tooth to tooth contact, during mastication or parafunction. Matching wear on occluding surfaces, & shiny facets on amalgam contacts are common:
Attrition
In attrition, enamel & dentin wear is at the same _____. Possible fracture of cusps or restorations appear in this disease.
Rate
Dental attrition is typically due to:
Bruxism
Loss of hard dental tissue by chemical processeses
Dental erosion
Broad concavities, with cupping of occlusal surfaces & dentin exposure. Incisal translucency aas well as wear on non-occluding surface. Amalgam restorations appear “raised” & have a non-tarnished appearance. Patients are usually hypersensitive & this is very common with GERD patients
Dental erosion
The caries balance is between:
Pathological factors & protective factors
Pathological factors found in the caries balance:
- acid-producing bacteria
- Frequently eating/drinking of fermentable carbohydrate
- Subnormal saliva flow and/or function
Protective factors found in the caries balance:
- saliva flow & components
- fluoride, calcium & phosphate
- antibacterials: chlorhexadine, iodine, xylitol, etc.
Many hydroxyapatite crystal exhibit a core of relatively more ______
Soluble carbonate apatite
The carbonate substitution in the lattice structure of enamel occurs primarily at the ______ in dental caries:
phosphate sites
In dental caries the core of carbonate apatite is eroded preferentially by acids due to its greater susceptibility to _____
dissolution
_____ may substitute for hydroxyl ions in hydroxyapatite, conferring greater stability & resistance to acidic dissolution
Fluoride
In dental caries, acid preferentially attacks the end of the crystals & the crystal is eroded along its _____ & from the inside toward the _____
C axis; edges
Bacteria responsible for enamel/dentin caries includes:
(4)
Strep mutans
Strep sorbrinus
Strep gordonii
Lactobacillus acidophilus
Bacteria responsible for root caries:
Actinomyces viscosus
As the process of dental caries (acid dissolution of the enamel) reaches DEJ, it spreads _____ due to _____
Laterally; due to branching of dentinal tubules at DEJ
After the caries spreads laterally once it reaches the DEJ it then penetrates towards:
The pulp within the dentinal tubules
After the caries penetrates towards the pulp within the dentinal tubules, a _______ is produced beneath the adjacent enamel surface
Substantial cavitation
After a substantial cavitation is produced beneath the adjacent enamel surface, there is initially a caries lesion that exhibits a small opening or orifice in the enamel & pyramidal shaped dentin lesion with the apex of the pyramid pointing towards the:
Tooth pulp
1 in 5 adults suffer from:
Dentinal sensitivity
The teeth most commonly affected by dentinal sensitivity:
Cuspids & bicuspids
Stimuli associated with dentinal sensitivity include: (6)
- Cold/hot beverages
- Sweet or sour (acidic) food or beverages
- Overly aggressive brushing
- Acidogenic plaque bacteria
- Cosmetic bleaching of teeth
- Clenching or bruxism
Direct stimulation of nerve endings in dentinal tubules describes what theory of dentinal sensitivity?
Direct innervation theory
Stimulation of odontoblasts that are coupled to nerves in the pulp describes what theory of dentinal sensitivity?
Transduction theory
Stimulation of dentinal tubules or exposed odontoblastic cell processes causes movement of tissue fluids within dentin tubules that, in turn, stimulates nerve endings in close association with dentin at the dentin/pulpal interface. This describes what theory of dentinal sensitivity?
Brannstrom’s hydrodynamic theory
Branntrom’s hydrodynamic theory has its roots in:
Charle’s Law
The volume of gas (or fluid) is directly proportional to the amount of heat applied at a constant pressure:
Charle’s Law
If heat is applied to a sensitive tooth, the volume of the fluid in the tubules increases, causing stimulation of the:
Nerve endings
If cold is applied to a sensitive tooth, the volume of the fluids in the tubules decreases, causing movement in the fluid & stimulation of:
Nerve endings
