Dentin Pulp Complex I Flashcards

1
Q

What is the function of a tooth?

A

Survive long-term cyclical loading

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2
Q

What is enamel?

What is dentin?

What is pulp?

A

Enamel - Mineralized protective component

Dentin - Mineralized structural component

Pulp - Main cellular component

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3
Q

What is dentin composed of?

A

70% - Inorgo

20% - Orgo

10% - H2O - Physiological fluid water

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4
Q

T/F - There is absolutely collagen (Mostly type I and some type III) in dentin.

A

TRUE

*Build on a collagen matrix

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5
Q

What is the inorgo material?

A

HYDROXYAPATITE

Like enamel crystals, but organized in a collagenous matrix

Ca10(PO4)6(OH)2 or Ca5(PO4)3(OH)2

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6
Q

Effectively, what is the HA in dentin?

A

Calcium phosphate crystals

F- can replace the OH, creating fluorapatite, also Zn and Mg, and others

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7
Q

T/F - Dentin is harder than bone, but weaker than enamel.

A

TRUE

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8
Q

Of dentin’s 20% organic material, what is the composition of it? Hint: 90:10

A

90% - Collagen (Mostly I, some III)

10% - Non-collagenous proteins

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9
Q

What are some non-collagenous proteins?

A

Dentin sialophosphoprotein (DSPP)

Dentin matrix protein-1 (DMP-1)

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10
Q

DSPP is cleaved further into what 3 proteins?

A

Dentin sialoprotein (DSP)

Dentin phosphoprotein (DPP)

Dentin glycoprotein (DG)

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11
Q

What cleaves DSPP?

A

BMP-1

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12
Q

Tell me about DSP.

A

Proteoglycan

Expressed in dentinal tubules

May act to PREVENT mineralization

Similar to DMP-1

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13
Q

Tell me about DGP.

A

Glycoprotein

Unknown fx

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14
Q

Tell me about DPP.

A

Only protein

Binds Ca2+, initiates HA formation

Attached to collagen

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15
Q

Defects in DSPP can cause what two malformations of dentin?

A

Dentinogenesis imperfecta II and III

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16
Q

What is dentinogenesis imperfecta type I?

A

RESULTS FROM OSTEOGENESIS IMPERFECTA (This is a defect in collagen I)

Pulp chambers filled with abnormal dentin

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17
Q

What is dentinogenesis imperfecta type II?

A

NOT ASSOCIATED WITH OSTEOGENESIS IMPERFECTA (This is a DSPP defect)

Pulp chambers fill with abnormal dentin

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18
Q

What is dentinogenesis imperfecta type III?

A

Enlarged pulp chambers, HYPOmineralization

Probably DSPP expression failure

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19
Q

T/F - All types of dentinogenesis imperfecta results in non-vital teeth.

A

TRUE

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20
Q

Dentin is made by what cells?

A

ODONTOBLASTS
-Line the pulp chamber

-Mesenchymal origin
—From dental papilla
—Ectomesenchymal origin

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21
Q

T/F - Odontoblasts are polarized cells which extend cellular projections into the dentin thru tubules.

A

TRUE

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22
Q

T/F - Dentin-pulp complex arises from dental papilla.

A

TRUE

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23
Q

IEE leads to formation of what?

A

Odontoblasts

24
Q

What cells/cellular tissues give the go for ameloblasts to lay down enamel?

A

Pre-dentin

25
Q

Look at the figures in the slides, especially for HISTO.

A

Do it

26
Q

Why is the DEJ scalloped?

A

Distribute shear forces

27
Q

Why is the DEJ shape critical? 2 reasons.

A

Defines shape of crown

Keeps dentin directly attached to enamel during loading (NO SHEARING)

28
Q

How is the DEJ bound together?

A

Merging of enamel HA and dentin HA crystals in ridges

29
Q

Which type of dentin is closest to the DEJ and the first layer of formed dentin?

A

Mantle dentin

30
Q

What are Von Korff’s fibers?

A

0.1-0.2 mm collagen III fibrils
—Associated with fibronectin
—*These are quite large fibers

31
Q

Tell me about the matrix formation of dentin.

A

Extend towards the IEE and branch into ground substance, and then forms DEJ with a scalloped edge

32
Q

What do developing odontoblasts begin extending into the developing matrix?

A

Tomes’ fibers

33
Q

Penetration of the IEE = ??

A

Enamel spindles

34
Q

Once a dentin protein scaffold is assembled, what is it ready for?

A

Mineralization

35
Q

Odontoblasts produce ________, moving away from the DEJ. When they do this they leave behind ________ ________ (future odontoblast process).

A

Matrix

Tomes’ fiber

36
Q

When does dentin mineralization start?

A

OD secreted Matrix vesicles, deposited along the future DEJ

37
Q

Once DEJ is formed, which dentin formation then commences?

A

Circumpulpal dentin

38
Q

T/F - Secreted matrix vesicles rupture and release mineralized matrix crystals.

A

TRUE

39
Q

_____ ______ ______ initiates odontoblast differentiation.

A

Hertwig’s Root Sheath

40
Q

What does HERS eventually become?

A

Rest cells of Malassez

41
Q

What are the three types of dentin and describe them.

A

Primary - 1st dentin formed during development, PRIOR TO ROOT FORMATION
—Mantle and initial deposition of circumpulpal dentin

Secondary - Tubular dentin laid down AFTER root formation
—Produced thruout life
—Closest to the pulp tissue

Tertiary - Dentin produced in response to insult
—Can have tubules, but often not
—Acts to seal off dentinal tubules

42
Q

What is the difference b/t reactionary tertiary dentin and reparative tertiary dentin?

A

Reactionary - Trauma does NOT damage odontoblasts

Reparative - Damages odontoblasts
—New ODs are formed
—*Less DSP and DMP-1, More BSP and OP

43
Q

Macrostructurally, what is the primary feature of dentin?

A

Tubules

44
Q

What are 3 main structures in dentin?

A

Dentin tubules - with OD process

Peritubular dentin

Intertubular dentin

45
Q

What is the orientation of dentinal tubules?

A

DEJ to the OD layer of the pulp

Fluid filled

*Surrounded by “collars” of peritubular dentin

Provide mechanical support to the enamel during loading
—Give the tooth some “flex” during loading

46
Q

T/F - After breaking thru the DEJ, bacteria move rapidly thru tubules.

A

TRUE

47
Q

What are dead dentinal tracts?

A

Trapped air in empty tubules - sealed off after OD death (insult or apoptosis)

48
Q

What is sclerotic dentin?

A

Occluded tubules

Glassy, translucent appearance

Occurs naturally, with age as peritubular dentin is deposited

*Starts apically, continues towards the crown with age

49
Q

What is interglobular dentin?

A

Areas of HYPOmineralized dentin

Formed when fusion of mineral contains vesicles fails

-Can be associated with Vit D deficiency or F exposure during initial dentin formation

More common near MANTLE dentin

50
Q

Dentin matrix is deposited continually at what rate?

A

4 microns (micrometers)/day

51
Q

What forms the lines of von Ebner?

A

A deposited dentin layer with different collagen fiber orientation

~20 micron intervals

52
Q

Mineralization occurs around ____ microns every _____ hours.

A

2

12

53
Q

What are the contour lines of Owen?

A

Enhanced lines that indicate disruption of tooth formation

—I.e. neonatal line, Striae of Retzius*

54
Q

What is the glandular layer of Tomes?

A

Dots around roots of ground sections

Mysterious

Maybe:
-HYPOmineralized dentin

Origin in Root dentin, so look for cementum, not enamel

Look at slide 30 for a picture

55
Q

T/F - Tubule density INCREASES as you approach the pulp.

A

TRUE

In other words, the tubule density at the DEJ is half of that at the pulp