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178 Cards in this Set

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It is the most highly mineralized tissue in the body, consisting of more than 96% inorganic material in the form of apatite crystals and traces of organic material.
Enamel
Surface is not smooth, but has lateral stripes,called ____.

More numerous at what region?

Absent where?
Perikymata
-Cervical (most numerous)

-Incisally//Gingivally (absent)
What is the clinical correlation between perikymata and caries
Teeth of many individuals are pitted. The perikymata and the pits provide attachment sites for bacteria (Clinically)
Enamel covering can be described as ___ and ___.
Thin and Hard
Enamel is essentially completely ______.Very hard, resists ______.Very brittle, easy to ______.Susceptible to acid dissolution.
Inorganic= Composition;
Attrition= Hardness;
Fracture= Brittle
Scanning electron microscope shows that enamel is composed of long rounded structures called ______, or _____. Known as the building block of enamel
Enamel Rods/Enamel Prisms
Enamel rods originate at the _____ and extend to the tooth surface. No rods terminate or originate away from the _____.
DEJ; DEJ
Rod and interrod enamel is made up of crystallites._____and _____ minerals occurring variously as hexagonal crystals as the chief constituent of phosphate rock and of bones and teeth.
There is ___ difference in the orientation of the rod and interred crystallites.
Carbonated Hydroxyapeptite; Calcium Phosphate Minerals; 45 degree
Rod and interred enamel are separated by a space called the ____. This is an important diffusion pathway from the tooth surface to deeper enamel.
Rod Sheath

NOTE:Prism sheath is not a structure,..it is a space and diffusion pathway
What is made 1st Interrod enamel or enamel rods
Inter- rod enamel
Crystallites + Rod Sheath account for ___ percent of enamel volume
10%
Enamel crystals are ____ shape in cross section
Hexagonal
How long is an enamel crystal
Not yet determined
The stripped pattern on the inner 2/3 of enamel. Stripes are called _____.
Hunter Schreger Bands
T or F:HSB don’t really exsists, it’s the name given as a result of sectioning
True
An enamel rod that starts somewhere on the DEJ will go towards the surface, then twist parallel to the surface, then towards the surface again, several times to end up laterally and occlusally from its point of origin. Therefore there is thicker enamel occlusally, The purpose of the tortuous path of enamel rods is to
Dissipate the tremendous forces of mastication thus reducing the incidence of enamel fractures.
Forces are distrupted _____ and _____.
Cervically and Laterally
there is a Line of Retzius for every _____thus a 1:1
Perikymata
Lines of Retzius extending from the enamel surface to deeper enamel. The lines of Retzius are an important _____ for substances from the surface to subsurface enamel
Diffusion Pathway (for lactic acid into enamel)
-Facilitate in enamel destruction
-Cervical region of tooth susceptible to bacterial attack
Surface etch of teeth results three patterns: Name them?
1)The rod is etched leaving sheaths.
2)Sheath areas etched deeper than rods.
3)Rods and sheaths etched at the same rate.
Etching is due to these 3 things:
Etching due to:
1) Crystal Orientation
2) Protein Protection
3) Reprecipitation
_____are fan-like protein deposits found in the enamel at the DEJ. Origin, composition, and function are not known
Tufts
_____ are cracks in enamel and/or dentin that occur during tooth formation.
-filled w/ residual matrix material
Lamellae
____are extensions of odontoblast processes that extend into the enamel near the DEJ

HINT: Dentin Structure
Spindles
DENTIN is very different from enamel in several respects: Name 3 ways it is different.
More organic (matrix is type I collagen)
More water
Viable tissue with cells
Enamel is more than ___% inorganic

Dentin, bone and cementum are ___% inorganic.

Soft tissue is mostly water and organic material.
Enamel 90%- Inorganic

Dentin, Bone, Cementum- 65%inorganic// 35% Organic
_____ are long-term incremental growth lines. Perhaps comparable to the ______of enamel.
Lines of Owen; Lines of Retzius
______are daily incremental growth lines in dentin.
Lines of Von Ebner
Acid etching dentin removes the mineral and reveals the ____matrix.
Collagen
Humans have ____ (there are many other kinds of dentin).

The dentin near the DEJ is _____.

The remainder of the dentin is ______.
Orthodentin= Humans;

Mantle dentin= dentin near DEJ;

Circumpulpal Dentin=remainder dentin
With age the dentinal tubules _____ as new dentin is deposited. The dentin at the periphery of tubules is ____ dentin.
Constrict; Peritubular
T or F:Peritubular dentin has different characteristics from intertubular dentin

EX:Calcium staining showing high mineral content of ____ dentin
True; Peritubular Dentin= high mineral content
After a tooth comes into occlusion, dentin continues to be deposited, but at a slower rate. Dentin formed after occlusion is called ____ Dentin
Secondary Dentin
Trauma results in localized formation of additional dentin within the pulp. This is ______. Some texts also refer to this as physiologic dentin or reparative dentin.
Tertiary Dentin
T or F:The tubules of tertiary dentin may or may not line up with the dentinal tubules of circumpulpal dentin.
True
Where is peritubular dentin located? Is it calcified?
Walls of tubules; highly calcified
Where is intertubular dentin located? Is it calcified?
In between tubules; highly calcified
Mantle dentin is the ___ layer of dentin and is the ___ to form
Outermost; first layer to form
Circumpulpal dentin is located where?
Around the pulp,...formed after mantle dentin
Which is more mineralized: Primary or Secondary Dentin
Primary- develops at a faster rate
Secondary Dentin
_____= rounded islands of mineralization either free in soft tissue or attached to the dentin.
Denticles
T or F: Dentinal tubules close with age
True
T or F:Mineralized tubules result in sclerotic dentin. Translucent.
True
Cementum is either cellular or acellular.
Acellular Cementum (primary)
_____= unmineralized layer
_____ layers formed. At least one layer over root, more in ____third. Formed ____ than cellular cementum. Has No cells. Width of layer never or always changes; Acellular cementum is the area for ____.
Cementoid; 1st layer formed; cevical; formed slower than cellular cementum; Width NEVER changes; attachment
Cellular cementum (secondary)
_____in lacunae with canaliculi. Formed after acellular. Many layers in ____third. More layers with time. Not in ____or ____. Very similar to____.
Cementocytes; Apical 1/3;Not in the Incisors or Canines; Bone
Intrinsic: fibers from ____
Extrinsic: fibers from ____
Cementoblast= Intrinsic;
Fibroblast of PDL= Extrinsic
Tooth formation starts at about the ____week of development
5th
Tooth development begins @ the ___ week of development?
5th
Neural Crest Derived Mesenchyme is induced by epithelium to produce ____
Condensed Mesenchym
Condensed Mesenchyme will differentiate in to what two structures
Dental Sac and Dental Papilla
Dental Papilla will become ____(dentin) and ____.
Odontoblast and Pulpal Fibroblast
Dental Sac will become the ____, _____ (cementum) and ___.
PDL, Cementoblast and alveolar bone
Name the 4 stages of tooth development
Dental Lamina, Bud, Cap, Bell
Incisor develop in the late ___ stage
Bell
Molars develop in the early ___ stage
Cap
Morphogenic Determinant is in the ____
Mesenchyme
Mesenchymal cells send processes that contact and become anchored to the ____.


Anchoring fibers are type ___ collagen
Basement Membrane; Type VII
Structure of the basement membrane, mostly type ____collagen.
Some of the large molecules that interact to form the basement membrane.
Fibronectin hyaluronan
Collagen IV
decorin
Laminin perlecan
Tenascin aggrecan
Type IV- BM
Cells attach to the extracellular matrix via ____, transmembrane molecules. On the cytosol side, integrins are connected to the _____.
Integrins; Cytoskeleton
Composite of how molecules of cells may attach to, and interact with the molecules of the extracellulare matrix.
The cytoskeleton is attached to the integrin via ________, ______, and ______
Paxillin, Talin, Vinculin
Paxillin stains:

Vinculin// Talin stains:
Ameloblast and Odontoblast

ONLY Ameloblast, not odontoblast
Define Condenstion:
Site where large numbers of mesenchymal cells become attached to the basement membrane within short distance (short time?).
Mesechymal cells quickly differentiate into odontoblast and secrete dentin matrix (type __collagen)
I
The first collagen secreted is mantle dentin, characterized by very large collagen fibers called _____.
Von Korff's Fibers
Mineralization of dentin first occurs within ____.
Matrix Vesicles
T or F: Mineralization of matrix vesicles spreads to surrounding collagen forming islands of mineralized tissue
True
Islands of mineralized dentin fuse to form the ___ dentin.
Note that no enamel has formed yet, but the ____ have elongated and the organelles for protein synthesis are in place.
There is some evidence that some enamel matrix proteins have been secreted into the dentin at this stage
Mantle; Pre-Ameloblast
Enamel matrix is deposited when
ameloblasts contact mineralized dentin
_____ and _____of mantle dentin forming the DEJ
Enamel Matrix and Von Korff's Fibers
Name the stages of Amelogenesis
Amelogenesis
Presecretory stage
Secretory Stage
Transition
Maturation Stage
Reduced Stage
Stopped @ Slide 127,...Start of Mechanisms of Bone Formation and Mineralization
Stopped @ slide 127,..Start of Mechanisms of Bone formation and Mineralization
Name 2 ways bones form
Endochondrial Ossification (requies cartilage precursor) and Mesenchymal Ossification
In endochondrial ossification the cartilage matrix (type ___ collagen) must be removed and replaced by bone matrix (type ___ collagen)
Collagen Matrix (Type II)

Bone Matrix (Type I)
Name the different pathways a mesenchymal cell can differentiate into upon environment, growth factors, or hormonal stimulus.
Fibrogenic (low cell density)
Myogenic
Chondrogenic (high cell density// low O2 tension)
Osteogenic (high O2 tension)
Osteoblast synthesize
Type I collagen
Alkaline Phosphatase
Osteocalcin
Collagenase
Prostaglandins
Resorptive Cells that contain acid phosphatase,collagenase, cathespins, and plasminogen activator
Osteoclast
These cells cover the surface of bone,..function is unknown
Bone Lining Cells
Name te two stages of mineralization?
1-Nucleation by a pure solution/ foreign material;
2-Crystal Growth
Name the 3 ways that mineralization may occur
Increasing Ca or Phosphate concentrations next to unmineralized area

Removal of inhibitors of mineralization (PPi, Mg, Ca binding proteins, Proteoglycans)

Synthesis of molecules that will promote mineralization (collagen, phosphoproteins, gamma carboxyglutamate, phospholipds)
Osteocalcin=

low or high mw

binds loosely or tightly to Ca++

contains ____that is post-transitionally modified,..vitamin K dependent

only in bone or other places in the body

measures ____ activity
low MW

Binds tightly to Ca++

Contains GLA- Gamma CarboxyGlutaminic Acid

Restricted to BONE

Measures Osteoblastic Activity
Phospholipids=

Histologically stain in the _____in endochondrial bone formation, @ predentin-dentin interface. Also at sites of _____ formation

Can serve as nucleation factors in _____deposition
Hypertrophic Zone; Enamel formation

Hydroxyapeptite deposition
High Serine Phosphoproteins=

found in low or high concentrations in bone/dentin

Serine residues bind to ____.
High

Bind to Phosphate
Collagen (in bone)=

Post-trascriptional modification differ due to a greater extent of ____ and ____.

Crosslinks are the same or different

Vitamin D def, can alter what

___ and ___ inhibit mineralization
Lysine Hydroxylation and Glycolysation

Cross-links are different

Crosslinking of Collagen Fibers

Mg and PPi= inhibit mineralization
PPi is made via the hydrolysis of ____.

What E catabolize PPi afterwards to make sure it doesnt interfere w/ bone mineralization

Analogs of PPi are ____ and also inhibit mineralization
ATP

Alkaline Phosphotase//Pyrophosphatase

Phosphonates
Mg inhbits mineralization,..what happens if there is a def of Mg.
Hypermineralization
-inspite of low ca in blood serum (to signal mineralization)
GAG's bind to Ca- this decreases or increase as mineralization proceeds

What is the GAG that predominates in bone mineralization.
decreases

Chondrotin Sulfate
Cellular control of bone mineralization is dependent on the presence of a ____.
Bone Membrane
Mitochondria accumulate ___ and ____.

Ca gradient in mitochondria increases in cartilage to what level
Ca and Phosphate

Level of Calcification and then disappears
Matrix vesicles=

Have a _____ in interior.

Arise from ____ by budding

High ____ and _____ enzymatic activity

Secreted in areas of ____
Amorphous Ca Phosphate in interior

Plasma Membrane

Alkaline Phosphatase and ATPase Enzymatic Activity


Calcification
What is sooooooo important about Bone Morphogenic Matrix

How many exisists
Well, it is decalcified, cell free bone powder that initiates cellular differentiation in cartilage and bone lines of embryonic tissue,...could be used as an IMPLANT MATERIAl

9
Bone composition=

% Inorganic, Organic, Water
60% inorganic

25% organic- collagen accounts for 90% of this

15% water
Ca circulates in plasma in one of three ways,...name them?

What is the most common way Ca is carried?

What is the protein that Ca is bound to in the plasma
Ionized, Protein Bound, and complexed

Ionized; (50%) Albumin:
What does complexed Ca mean?
Ca is carried by other molecules such as phosphate or citrate
What is the major affect of hypocalcemia/hypercalcemia?
Hypo-Muscular Tetany

Hyper-Lethargy,GI probs, cardiac arrthmyias, calcification of soft tissues
Approx. ___of Skeletal Ca is exchangable w/ ECF
1%
The majority of Ca, P, and Mg is where in the body?
Skeleton
Mg and Ca are mainly in the ___ forms in the plasma and P is mainly in the ___ form.
Ionized; Complex
Serum Ca levels are mainly controlled by what three factors
PTH, Calcitonin, Vitamin D
PTH increases/decreases PLASMA Ca
Increase
PTH is a ___ chain PP made of ___ aa lacking ___.
Single;84aa;cysteine
1-34 aa amino terminal sequence in PTH has what importance
Mobilization of Ca activity
PTH is synthesized as a ____ hormone w/ 37 aa added to the amino terminal end

Two cleavages occur,..name where?
Preprohormone; cleaved @ 31//6 aa
What stimulates PTH secretion primarily and secondarily
1- low Ca levels
2- low mg levels
Where is PTH degrades
LIVER and Kidney
What does PTH do when it is active?
Mobilize bone Ca and activates activity of Vitamin D metabolism in Kidney
Calcitonin (CT) decreases/increases plasma Cs
Decreases
CT has ____ aa in a single PP chain
32 AA

ALL are needed for function
CT is secreted from where
Parafollicular cells in Thyroid
What triggers CT secretion
(2 things)
High Ca (ionized) levels and Gastrin
1/2 life of CT is ___
4-5 min
What is CT function?
Block PTH activity on bone
Vitamin D increases/decreases plasma Ca?
increases
7-dehydrocholesterol is converted into cholecalciferol (vit D3) by ____ in skin
UV irradiation in skin
Vit D3 is converted hydroxylated @ the 25th position in the ____ yielding _____.
Liver- 25 OH

-Loosely controlled
25-OH is hydroxylated at the 1 postion in the ____ to yield____. THe E for this rxn is ____.
Kidney; 1,25 (OH)2 Vit D3
Renal 1 alpha Hydroxylase

Tightly controlled
What does vit d3 do when active?
Increase Ca absorption in GUT// acts secondarily w/ PTH on Ca in bone
Def of Vit D3 in children is called ___ and in adults is called ____.
Rickets// Osteomalacia
Bone resorption can be defined as removal of both _____ and ____ that is mediated by ____.
Mineral Phase + Matrix

Mediated by Osteoclast
Osteoclast are SMALL multinucleated,cells w/ normal looking nuclei,...T or F
F:Large cells, Multi-nucleated w/ Irregular Shaped Nuclei
Osteoclast actively resorbing bone show this structure
A ruffled border
Osteoclast stain for ____, and contain ____ receptors.
Tartate Resistant Acid Phosphotase, Calcitionin
Osteoclast dont respond to PTH directly,...instead they respond to what?
Secretory products of PTH stimulated by osteoblasts
____ are known to aid in the bone resorption process by degrading collagen @ acidic pHs
Cathepsins
Name 3 situations in which bone resorption exceeds bone formation?
1)Hyperparathyroidism (imbalance in Ca homeostatic metabolism)

2) Infection//Inflammation activates bone cells by cytokines and other inflammatory mediators produced by immune/inflammatoru cells

Lack of mechanical stress on bone (basically you dont use,..you lose)
Name the age:

Excessive resorption is coupled w/ decreased bone formation
Post-Menopausal Women
Decreased rates of bone formation and decreased rates of bone formation
Elderly
Resorption increase w/ normal rates of bone formation
Pre-Menopausal Women
T or F,...PTH when given at pulsated doses can stimulate bone formation
TRUE!
In vivo,..PTH is associated w/
Increased Osteoclasts

PTH also stimulates bone resorption on organ culture
Necessary permissive cofactor for PTH but does not stimulate bone resportion in vivo

When does it stimulate bone resorption
Vit D3

Organ Culture
Calcitonin is most affected by what
Its antagonist- PTH
This molecule is known to stimulate Osteoclast activity,..in fact it is called an osteoclast activating factor
IL-1
This molecule,..like IL-1 stimulates osteoclast activity: it is the primary mediator of immune and inflammatory processes,...stimulates bone resorption in vivo// in vitro
TNF
This molecules is produced by osteoblast to aid in bone resorption w/ osteoclast.

Name the molecule that works w/ this molecule in sitmulating stem cell populations leading to osteo clast

This molecule works w/ ____ in organ culture in bone resorption
IL-6

IL-3

IL-1
When macrophages are exposed to stimuli these molecules are potent stimulators of bone resorption in Organ culture
Prostaglandins
Esp- PGE2
Excessive glucocorticoids is associated w/ what
Increased bone LOSS
Def Androgens and Estrogens are associated w/ what
Increased bone MASS
___ loss is associated w/ osteoporosis in post-menopausal women

HOW?
Estrogen; Estrogen sensitizes bone cells to the effects of circulating PTH (makes them more responsive)
____ has been shown to slow osteoclast activity w/ no affect on bone formation
Estrogen Therapy
Estrogen inhbits this molecule
IL-6 being released from osteblast
Resorptive affects of ___ and ___ are dose dependent and can stimulate bone formation
PTH and Prostaglandins
___ and ___ lead to increase bone fragility
Cadmium and Lead
-Inhibits syntheis of Vit D3
___ is a necesary factor for normal bone growth and maturation
Zn
What occurs during cellular differentiation
Cells are responding to changes in there external enviornment...so they are altering there genome activity by changing there genetic expression which is most of the time irreversible
How does the cell know that there is a change in the external enviorment
It recieves a signal,...this signal affects transcription
Name some of the most common primary signals that a cell recieves that affect transcription
Growth Factors
Hormones
Retinoic Acid// Derivatives

Can come into the cell or act on the surface of the cell
Signals acts in two ways to affect transcription,...name them?
Directly- act as a transcription factor

In directly- affect the activity of a transcription factor
How does a steroid hormone work?
Crosses cell membrane, binds to an intracellular receptor,.. attaches to HORMONE RESPONSE ELEMENT in genome and activates 50-100 genes
____ modulate intracellular events via G. Proteins, Tyrosine Kinases (DIRECTLY), Tyrosine Kinase associated mechanisms , Serine-Threonine Kinases or alteration in ion channels
Cell Surface receptors
Cytokines may direclty activate ____ by phosphorylation of a TYROSINE residue or indirectly activate through a ___
STAT (Signal Transducer and Activator of Transcription; JAS (Janus Kinase
Different second messengers,..like cAMP activate these 2 pathways
MAP (mitogen activated protein) kinase pathway

RAS
Give and example of physical re-arrangement of the genome
Linking of the V, D, and J segments to a C gene segment in B- Lymphocytes
What is a feed-back loop

Give and example
When a regulatory protein activates its own transcription factor to ensure the gene is ALWAYS expressed

Myo-D transcription factor in muscle
_____ is the reason for the differences in tissue type
Pattern Formation

In some tissues,..position is important (ie teeth)
How does limb formation begin
By Bilateral outgrowths lateral plate mesoderm surrounded by epithelium
How does a limb bud know where to grow
by Fibroblast growth factor 8 (FGF-8)
- in fact implantation of FGF8 will stimulate limb bud formation
2nd- The Bilateral outpockets in mesoderm (surrounded by ectoderm gets ____ along the apex and into the ____.

As this is occuring the posterior ____ forms the zone of ______.
Thicker; Apical Ectodermal Ridge (AER)

Mesenchyme; Zone of Polarizing Activity (ZPA)
What is the Zone of Polarizing Activity resposible for?
Anterior-Posterior Patterning of the digits (pinky to thumb)
ZPA is mediated through what protein
SHH (Sonic Hedge-Hog) Protein??
Grafting of cells from a ZPA to the anterior portion of the limb bud resulted in what?

What does this mean?
Resulted in Mirror Image formation of digits

ZPA is involved in Pattern formation

Application of SHH does the same thing,..so they work together
The Apex Ectodermal Ridge (AER) regulates what?
Proximal-Distal (shoulder-digits)
Removal of AER results in what

Removal of AER @ successive later stages @ later stages results in what
Trucation of the Limb

Progressive loss of more and more distal elements
AER functions through the release of ___ by it maintaining the cells beneath (progress zone) the apical ectodrmal ridge
FGF's
W/ the loss of this receptor an embryo will be limbless
FGFR2 receptor

-Uncouples FGF8-FGF-10
Dorsal-Ventral (back of hand) to palm is specified by what three factors
En-1, Wnt7a and Lmx-1

interactions btw the three fine tune positional information
___ induces ectopic bone and cartilage formation
SHH
____, ____,and ____, work together to stimulate mesenchymal cell progression into chondrocyte linage
SHH, BMP2, Ihh (indian hedge-hoge)

-also regulate Pre-osteoblast differentiating into osteoblast

-Parathyroid hormone related peptide also aids in this process
BMP belongs to the ____ superfamily of growth and differentiation factors
TGF-B Superfamily
____ and ___ are expressed in perichondrium of developing limbs but ____ is absent in joints
BMP2 and 7; 7
Retinol A is metabolized into ____ and _____
Retinal and Reinoic Acid
____ (AKA:____) during pregnacy will result in defects of the ear, mandible, secondary palate, thymus, and heart
Accutane (13-cis reinoic acid)
In limb formation ___ incuces production of polarizing signals
Retinoic Acid
These genes are required for the proliferation of skeletal progenitor cells
Hox genes
-4 hox gene clusters= code for 39 genes= encode homeodomain Transcription factors
Hox gene combo determine length of upper arm (__ and __) lower arm (___, ___, ___) and digits ( ___, ___, ___)
Upper arm= 9, 10

Lower arm= 10, 11, 12

Reduction in gene dose will result in trucation of the corresponding anatomical regions

Digits= 11, 12, 13
Responses to the ECM are most likely mediated through the ___
Integrin (link ECM w/ cell membrane and interal structures)
Can a differentiated cell change
Yes if put under the appropriate conditions
Do osteoclast have receptors for PTH
NO
Name three factors that are important in the control mechanisms in regulating osteoclast differentiation
RANK

RANKL

Osteoprotegerin