Structure of Enamel and Dentin (Larsen 4)

Question 1

______ covers the anatomical crown. It is thickest over the _____ and decreases in thickness toward the ______.

Answer 1

• Enamel
• Cuspal tips
• Cemento-enamel junction

Question 2

Enamel enables the tooth to _____ and _____ food and protects the _____.

Answer 2

• Grind and crush

- Dentin

Question 3

Physical Properties of Enamel

Answer 3

• Hardness
• Brittleness
• Color

Question 4

Enamel is the _______ substance in the body because of the ______ and _____ of hydroxyapatite crystals.

Answer 4

• Hardest

- Number and arrangement

Question 5

Enamel is very ____ because of the high inorganic content, and has to be supported by _____ to prevent breakage.

Answer 5

• Brittle

- Dentin

Question 6

Enamel is ______ in color which allow yellow of dentin to come through. The tooth color depends on the ______ of the enamel and the _____ of the dentin.

Answer 6

• Translucent
• Thickness
• Color

Question 7

Enamel rods extend from their origins at the _____ to the _______.

Answer 7

• Dentinoenamel junction (DEJ)

- Enamel outer surface

Question 8

The ______ is a bundle of crystal ribbons

Answer 8

Enamel rod

Question 9

The ______ is between and around rods at a different angle

Answer 9

Interrod

Question 10

The ______ is a hypomineralized sheath surrounding each enamel rod that contains _______ material (enamel proteins).

Answer 10

• Rod sheath

- Organic

Question 11

______ are viewed only with reflected light and appear as light and dark bands.

Answer 11

Hunter-Schreger Bands

Question 12

______ result from the arrangement of hydroxyapatite crystals (orientation of rod and interrod)

Answer 12

Hunter-Schreger Bands

Question 13

The dark, horizontal ______ on the enamel rod represent daily growth of rod segments and are slightly hypomineralized.

Answer 13

Striations

Question 14

The ______ are concentric dark bands that follow the contour of the tooth surface and represent _______ areas of rods resulting from 7-11 days of growth or during physiological stress.

Answer 14

• Striae of Retzius

- Hypomineralized

Question 15

The ______ is an accentuated hypomineralization associated with birth in all primary teeth and first molars of secondary teeth.

Answer 15

Neonatal line

Question 16

The ______ are horizontal ridges on the surface of the tooth. They are surface manifestiations of the termination of _______.

Answer 16

• Perikymata

- Striae of Retzius

Question 17

Gnarled enamel is twisted rods of enamel under the _______ which provides _______ against forces of mastication.

Answer 17

• Cuspal tips

- Greater strength

Question 18

The DEJ is _______ which allows for the attachment of the two mineralized surfaces.

Answer 18

Scalloped

Question 19

_______ are caused by the movement of ameloblasts from the DEJ. They are enamel rods in different directions that extend 10-20% the distance from ____ to ______ and are ________ (contain enamel protein).

Answer 19

• Enamel tufts
• DEJ to occlusal surface
• Hypomineralized

Question 20

______ are an extension of the dentinal tubule crossing through the DEJ. They are surrounded by enamel and shorter than tufts.

Answer 20

Enamel Spindles

Question 21

______ appear as lines extending from the surface toward the DEJ and represent a defect filled with organic material. It is hypomineralized and not tubular.

Answer 21

Enamel Lamellae

Question 22

Physical Properties of Dentin

Answer 22

• Color (yellow)

- Compressibility and Elasticity (Serves as shock absorber for enamel)

Question 23

Hardness & Density comparison of Bone, Enamel, and Dentin

Answer 23

Enamel > Dentin > Bone=Cementum

Question 24

The ______ is a tube that extends from pulp chamber or root canal to either the junction with the enamel (DEJ) or cementum (DCJ).

Answer 24

Dentinal Tubule

Question 25

Features of Dentinal Tubules

Answer 25

- Odontoblastic Processes | - Nerves and Sensitivity

Question 26

The ________ of Dentinal Tubules are 3 or 4 brances of cell processes of adjacent cells.

Answer 26

Odontoblastic Processes

Question 27

The ______ of the Dentinal Tubules may extend 1/3 the distance up the tubule. ______ is when the nerves arise from the pulp and transmit any stimulus as pain.

Answer 27

- Nerves | - Sensitivity

Question 28

_____ Dentin immediately surrounds the odontoblastic cell process and is hypermineralized, while ______ Denin is the remaining dentin that is not directly surrounding odontoblastic cell process.

Answer 28

- Peritubular | - Intertubular

Question 29

_____ Dentin makes up the body of tooth and is formed before eruption. Examples are the Mantle and Circumpulpal dentin.

Answer 29

Primary

Question 30

______ Dentin forms only after tooth eruption. It is internal to primary dentin and borders the pulp.

Answer 30

Secondary

Question 31

______ Dentin forms only in response to trauma to the pulp in a localized area.

Answer 31

Tertiary or reparative dentin

Question 32

_____ Dentin forms slowly throughout life. Masticatory forces cause a bending of the tubules.

Answer 32

Secondary

Question 33

_______ represent major change of physiology during several days of growth in dentin. They are hypomineralized and are equivalent to the Striae of Retzius of the enamel.

Answer 33

Contour Lines of Owen

Question 34

The _______ is a hypomineralized line caused by birth.

Answer 34

Neonatal line

Question 35

Dentin formed _____ birth is better quality than _____.

Answer 35

- Prior to | - After birth

Question 36

______ is produced in response to an insult to a tooth. The _____ form a patch of dentin to protect the pulp. The tubules are sparse and irregularly arranged, and the matrix is poorly mineralized (hypomineralized).

Answer 36

- Tertiary or Reparative Dentin | - Odontoblasts

Question 37

______ is found in the crown and root. They are ______ areas between globular mineralization fronts.

Answer 37

- Interglobular Dentin | - Hypomineralized

Question 38

______ are found in the root along the DCJ. They are small hypomineralized spheres that represent the highly branched terminal ends of the odontoblastic cell processes.

Answer 38

Granular Layer of Tomes

Question 39

After Severe Trauma, a _______ is an area of empty dentinal tubules that generally result from bacteria invasion. Odontoblastic cell processes retreat because of bacterial toxins leaving empty space.

Answer 39

Dead Tract

Question 40

After Severe Trauma, ________ is hypercalcified dentin under the dead tract that forms a protective barrier.

Answer 40

Sclerotic Dentin

Question 41

______ is hypermineralized as dentinal tubules are filled in by the constant production of dentin. It is transparent.

Answer 41

Sclerotic Dentin