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Question 1

What is the chemical makeup of enamel?

Answer 1

96% mineral-hydroxyapitie (OH- + Calcium Phosphate) crystals, 3.5% water, and 0.5%organic material(type I collagen)

Question 2

What is the chemical makeup of dentin?

Answer 2

70%mineral-living tissue, 2nd hardest substance in the body

Question 3

What is the chemical makeup of cementum?

Answer 3

45-60% mineral. Living, bone like tissue

Question 4

Where is enamel the thickest and how thick is it at this surface?

Answer 4

The occlusal surface is thickest at 2.5mm

Question 5

What is the optimal level of fluoride recommended by the US PHS?

Answer 5

0.7 to 1.2 ppm

Question 6

How do type I collagen fibers help form enamel rods?

Answer 6

The ameloblasts send out the collagen fibers like a scaffolding and then pull them back for optimal room for rod and inter rods.

Question 7

Is the DEJ smooth?

Answer 7

No, it is “scalloped” or “stair-step like” to help resist shearing forces.

Question 8

What are the three types of enamel imperfections? Rank the size.

Answer 8

1)Lamellae-HUGE, span the full thickness of the enamel. Filled with organic material 2)Tufts shorter projections from the DEJ, branched. 3)Spindles-odontoblast processes getting caught in ameloblast epithelium. Spindles have a mix of enamel and dentin :)

Question 9

Where is thicker dentin? DEJ or near pulp?

Answer 9

Thicker as odontoblasts move towards PULP

Question 10

How are odontoblasts nourished?

Answer 10

By the vessels in the pulp

Question 11

What are the 5 types of dentin?

Answer 11

1)Predentin-think wet concrete on sidewalk 2)Primary dentin-makes up MOST of the tooth 3)Secondary dentin-develops after ROOT formation is complete. Proceeds slowly and REDUCES the size of the pulp cavity 4)mickey MANTLE dentin-The dentin under the crown 5)Tertiary dentin: made in response to CARIES, attrition, and restorations. Broken down into 2 subcategories Reactionary (existing odontoblasts)and Reparative(NEW odontoblasts)

Question 12

How do dead tracks in dentin form?

Answer 12

The loss of odontoblasts

Question 13

What is the nerve plexus of Raschkow?

Answer 13

The pulp/dentin nerve complex “loops” of nerves extending past the odontoblast and into the predentin

Question 14

What are the three mechanisms of dentin sensitivity?

Answer 14

1) Dentin CONTAINS NERVE ENDINGS that respond to stimuli 2)ODONTOBLASTS serve as pain receptors and are connected to the pulp innervation 3)FLUID movement though the dentin tubules which stimulates pulpal free nerve endings near the odontoblasts

Question 15

What argues against the dentin containing nerve endings sensitivity issue?

Answer 15

Although there are some nerves in the dentin, Bradykinin and histamine show no effect when applied to the dentin.

Question 16

What are problems with odontoblasts as receptors dentin sensitivity theory?

Answer 16

Although odontoblasts can polarize and propagate a signal, the membrane potential is rather small. Anesthetics do not work on dentin sensitivity.

Question 17

Describe why the fluid theory of dentin sensitivity is most logical.

Answer 17

Fluid movement thru the dental tubules can distort nerve endings in the pulp causing pain. Explains anesthetic issue and other common issues with the other two theories.

Question 18

What are the cells that produce cementum? What are they initially called and what do they develop into?

Answer 18

Cementoblasts, they look like fibroblasts. They then develop into dendritic cementoCYTES-look like osteocytes.

Question 19

What are the functions of acellular and cellular cementum?

Answer 19

Acellular: Anchorage, Remember you want to grab the shaft towards the middle for stability?? Cellular: Adaptation to tooth wear, movement, and repair.

Question 20

What is the term for the DCJunction? What is it made out of?

Answer 20

The granular layer of TOMES, collagen and non collagen matrix proteins

Question 21

What are the three possibilities for the CEJ? What are the percentages associated with it?

Answer 21

An overlap: 60% of the time. A flush abutment: 30% of the time and a gap, exposing the dentin: 10% of the time.

Question 22

What are the four main cell types of the pulp?

Answer 22

1) odontoblasts 2)fibroblasts 3)undifferentiated ectomesenchymal cells (((PSC’s!!! can diff into odonto’s and fibro’s))) 4)WBCs

Question 23

What are the four zones of pulp?

Answer 23

1)Odontoblastic Zone-odontoblasts here 2)Cell free zone of WEIL “WHILE”-loosely arranged CT fibers between odontoblasts and fibroblasts 3)Cell Rich Zone-High cell density fibroblasts, WBCs StemCells 4)Pulp Core-blood vessels and nerves in a gelatinous CT matrix.