Dental Materials I

Front 1

1. What are the surface layers?

Back 1

1. Adsorbed monolayer
-monolayer is what comes into contact
-i.e titanium has a monolayer of oxide
2. Higher energy surface layer
-most surfaces have higher energy at surface

3. Bulk of material (properties looked at earlier)

Front 2

2. When bone adheres to titanium what happens?

What does the screw provide?

Back 2

Cellular adaptation

Screw does not provide stability, just initial placement

Front 3

3. What are some surface analysis techniques?

What does spectroscopy generally allow us to do?

Back 3

xray photoemission spectroscopy
electron spectroscopy
auger electron spectroscopy

Look at composition of surface
**surface atomic composition

Front 4

4. What surface techniques allow us to physically look at the surface?

What types of studies are these?

Back 4

SEM
Nano- and micro-indentation

Hardness studies
-resistance to indentation

*use diamond indentor to fracture specimen

Front 5

5. What is a dynamic hardness testing curve?

Back 5

Looks like stress-strain curve

As applied force increases, depth of indentation increases

Get modulus but just on surface

Front 6

6. How do surface and interior energy compare?

How is the surface tension of liquids?

Back 6

Surface energy is higher than energy in interior

Molecules lost from evaporation so greater average separation therefore higher energy of attraction

Front 7

7. What is the surface energy?

What is the total surface energy of a system?

Back 7

Surface energy = energy/area
-high bond strength = high surface energy

Total surface energy of system =
surface energy x total area

Front 8

8. How do a polish and roughed surface differ in surface area?

Back 8

Rough surface increases area so increase interaction with substrate

Polished surface decreases surface area so decrease surface energy (less tarnish and corrosion)

Front 9

9. What is wetting?

What is contact angle?

What is capillary penetration?

What is adhesion?

What is cohesion?

Back 9

Spreading of a liquid drop on a solid surface

A measure of wetting (how much does it bend)

Liquid movement into a crevice

Surface attachment of 2 different materials

Surface attachment of 2 like materials

Front 10

10. What is the contact angle for good wetting?

What is it for bad wetting?

Back 10

Less than 90 degrees

Greater than 90 degrees

Front 11

11. How do contact angle and percent detail relate?

How do contact angle and castability of high strength stone relate?

Back 11

As CA goes down, percent detail goes up

Inverse relationship

Front 12

12. What are some examples of wetting?

Back 12

1. Adhesion of a denture base to oral tissue
2. Soldering of a bridge undercasting
3. Repair of an acrylic orthodontic appliance
4. Cementation of a restoration

Front 13

13. What is perfect wetting?

How are the contact angles of some dental materials?

Back 13

0 degree contact angle (no bending, spreads out)

Teflon: 110
Amalgam/Acrylic: 80/75
Gold Alloys: 40-50
Etched enamel (sealants): 0

Front 14

14. What is the penetration coefficient?

What does good penetration result from?

Back 14

Surface tension x (cos Contact Angle) /
2 x viscosity

1. High surface tension
2. Low contact angle
3. Low viscosity

Front 15

15. If there is no reservoir what happens?

Back 15

Get adhesive force

i.e. complete dentures

Front 16

16. What are colloids?

What is a colloids surface area like?

Back 16

Highly dispersed system of fine particles of one phase within another

Incredibly high surface area per volume so very reactive

Front 17

17. What are the two phases of colloids?

Back 17

1. Dispersed phase (colloid itself)
-larger than a molecule but not visible to naked eye

2. Liquid phase

Front 18

18. What are examples of colloids?

Back 18

1. Fine dispersions
2. Gels
3. Emulsions
4. Films
5. Foams

Front 19

19. What are 3 properties of colloids?

Back 19

1. Very large surface area of the dispersed phase

2. Increased surface area

3. Increased potential for surface reactions

Front 20

20. What are three colloids?

Back 20

1. Hydrocolloid

2. Colloidal silica in composites

3. Anti-rust water/oil mixtures

Front 21

21. What is the gel in a colloid system?

What is the sol in a colloid system?

Back 21

Gel: semisolid stone
-hydrosol
-hydrogel
-hydrocolloid

Sel

Front 22

22. What two things do water based gels do?

Back 22

1. Syneresis
-hydrocolloid system in gel state that continuous to interweave fiberal network and water comes off
**sweat beads come off

2. Imbibition
-put fibral network in water and it will tiake in excess water and expand
**decrease strength

Front 23

23. What is emulsion?

Back 23

Water/oil

So evenly dispersed that oil doesn't sit on top of water

Front 24

24. What is sorption?

What is the difference between adsorption and absorption?

Back 24

General term for taking up something

Adsorption: surface

Absorption: body

Front 25

25. What is isotropic?

What is anisotropic?

Back 25

Same in all directions
-doesn't have a grain
-i.e. gypsum

Not the same in all directions
-has a grain
-i.e. wood, enamel, dentitn

Front 26

26. How are dentin and enamel interdependent tissues?

Back 26

Enamel needs dentin's support

Dentin needs enamel's seal and protections

**dentin is a live tissue and it not as strong

Front 27

27. What are the components of dentin?

Back 27

1. 75% inorganic
-small hydroxapatite crystals

2. 20% organics
-mostly collagen

3. 5% water

Front 28

28. What are some properties of dentin?

Five things...

Back 28

1. Good compressive strength

2. More resilient than enamel

3. More susceptible to acids attack than enamel b/c not as mineralized and has tubules

4. Vital tissue with odontoblast processes

5. Continued formation: secondary and reparative

Front 29

29. What is secondary dentin?

What is reparative dentin?

Back 29

Formed after initial formation of tooth

Formed in response to insult (localized formation)

Front 30

30. What dentin is mineralized?

Where is this located?

Back 30

Peritubular dentin

Right around dentin tubules

Front 31

31. What is the hydrodynamic theory?

Back 31

Primary theory for why dentin is painful

Fluid moving through dentin tubules is responsible for pain in dentin

Front 32

32. What is predentin?
Primary dentin?
Mantle dentin?

Back 32

Organic matrix of dentin that is formed prior to mineralization

Most dentin in the tooth. Dentin formed up until completion of root formation. Also called “circumpulpal” dentin

Thin outer-most layer of dentin adjacent to enamel with unique mineralization pattern and structure

Front 33

33. What is Secondary dentin?
Tertiary/reparative dentin?
Sclerotic dentin?

Back 33

Dentin that forms after root formation is complete, but not specifically in reaction to various stimuli as in tertiary dentin

Dentin that forms after root formation is complete AND in reaction to stimuli such as attrition, caries, or cavity preparation

Dentin in which the tubules have become occluded with calcified material, appearing glassy and translucent in thin section

Front 34

34. What is peritubular dentin?

Wat is intertubular dentin?

Back 34

Dentin immediately surrounding the dentinal tubules

Dentin surrounding and in between adjacent dentinal tubules and their associated peritubular dentin

Front 35

35. How are the dentinal tubules near the CEJ?

How are the dentinal tubules near the pulp?

Back 35

Superficial
-narrower
-more % intertubular (more spread out)

Deep
-wider
-less % intertubular (less spread out)

Front 36

36. What are smear layers?

What are smear plugs?

Back 36

Layer of debris on cut dentin surface and plugging cut dentinal tubules, resulting from operative procedures on dentin

Not part of normal enamel - man made by instruments

Front 37

37. What is the composition of enamel?

Back 37

1. 95% - 98% inorganic by weight
-hydroxyapatite crystals arranged in "rods" or "prisms" (multiple hydroxyapatite crystals)

2. 1% - 2% organic (amelogenins)

3. 4% water by weight

Front 38

38. What are striae of retzius?

Back 38

LInes formed during aposition (growth of tooth)

Dark lines in enamel in longitudinal sections probably representing incremental growth; neonatal line is a special example

Front 39

39. What are perikymata?

Back 39

Lines expressed on outside of tooth

Enamel surface expression of the the Striae of Retzius

Front 40

40. What is the enamal/prism structure of enamel?

Back 40

Prism: A thin film of proteins, glycoproteins and mucins of salivary origin found on the enamel surface

Rod: The basic organizational unit of enamel structure. Rods are composed of many long hydroxyapatite crystals

*big so can fracture them
*grain is perpendicular to surface of enamel

Front 41

41. How is the compressive strength, tensile strength, modulus of elasticity, and hardness of enamel compared to dentin?

Back 41

1. Enamel's compressive strength is 100 MPa greater

2. Dentin's tensile strength is 5x stronger than enamels

3. Enamel has high modulus of elasticity (stiff)

4. Dentin has low modulus of elasticity (flexiable)

5. Enamel is a lot harder (more resistant to indentation)
*almost as hard as porcelain/as hard as nickel-chromium alloy

Front 42

42. How is the thermal conductivity for dentin and enamel?

Back 42

About the same

**Amalgam and gold alloys have a higher thermal conductivity

Front 43

43. What are some properties of enamel?

Seven things...

Back 43

1. Translucent
2. Good compressive strength
3. Hard, stiff, brittle (can't be elongated)
4. Wear-resistant
5. Acid-soluble
6. Non-vital tissue
7. No further formation after amelogenesis

Front 44

44. What is meant by enamel etch?

Back 44

Heads and tails interlock

Front 45

45. What is biocompatible?

What is biomimetic?

What is bioactive?

Back 45

Material will not adversely affect biological state and function of surrounding tissue

Mimics natural tissue

Material causes biological processes (either accelerate or depress)

Front 46

46. What must materials be biocompatible with?

Back 46

Pulpal

Gingival/periodontal

Oral mucosa

Bone

Systematic considerations

Front 47

47. What are three clinical examples of the necessity for biocompatibility?

Back 47

1. Endodontic filling materials and periapical bone

2. Subgingival reostorations and gingival tissue

3. Restorative materials and oral mucosa

Front 48

48. What are the four zoens of bioactivity?

Back 48

1. Sulcus

2. Epithelial attachment

3. Connective tissue attachment

4. Periodontal ligament

Front 49

49. What are three test types of biocompatibility?

Back 49

1. In vitro
-cytotoxicity, cell metabolism, cell function, mutagensis

2. In vivo (animal)
-mucous membrane, implantation

3. Usage
-animal or human

Front 50

50. What is osseointegration?

Back 50

Structural and functional association between living bone and the surface of a functioning implant

Front 51

51. Where are initial screening test of biocompatibility done?

If there are not odontoblast processes is it good or bad?

Back 51

Monolayer fibroblasts

Bad

Front 52

52. What is the progression of biocompatibility?

Back 52

Bottom of pyramid
-unspecific toxicity (primary)

-specific toxicity (secondary)

-Clinical trials (usage)

**number of tests needed decreases with the progress of testing