Chapter 6-2 Tooth development and Eruption

Question 1

When does root development begin

Answer 1

After crown is completely formed and tooth begins to erupt

Question 2

What structure is responsible for root development

Answer 2

Cervical loop

Question 3

What is the cervical loop consists of

Answer 3

Inner enamel epithelium and outer enamel epithelium

Question 4

What is the Hertwig Epithelial Root Sheath (HERS)

Answer 4

Elongated cervical loop that encloses dental papilla tissue

Question 5

What is te HERS responsible for

Answer 5

Shaping roots by inducing dentin formation of root area

Question 6

Outer dental papilla cells undergo what processes (2) to become what?

Answer 6

Undergo induction and differentiation to become odontoblasts

Question 7

What does HERS induce?

Answer 7

Odontoblastic differentation

Question 8

Odontoblasts undergo what to do what?

Answer 8

Undergoes dentinogenesis to begin secreting predentin

Question 9

When root dentin formation is complete what occurs?

Answer 9

Basement membrane disintgetration
HERS disintegration
Rise of ERM from HERS

Question 10

What is Epithelial rests of Malassez (ERM)

Answer 10

Cells that form from disintegrated HERS cells

Question 11

What do ERM cells end up in?

Answer 11

Periodontal ligament (PDL)

Question 12

Order of layer formation

Answer 12

Dentin, cementum, Pulp

Question 13

Cementum formation begins with?

Answer 13

Cementoblasts undergoing cementogenesis which causes appositional growth of cementum in tooth area when HERS disintegrates

Question 14

Explain the process of cementogenesis

Answer 14

Lays down cementum matrix or cementoid

Question 15

What happens to cementoblasts during cementum formation

Answer 15

Become trapped in the cementum they produce

Question 16

Dentinocemental junction (DCJ) occurs as a result of what?

Answer 16

Apposition of cementum over dentin

Question 17

What cells form the pulp?

Answer 17

Central cells of dental papilla

Question 18

What structure causes teeth to develop multiple roots?

Answer 18

Differential growth of HERS

Question 19

What determines the number of roots the mature tooth will have?

Answer 19

Number of extensions of the cervical loop

Question 20

Ectomesenchyme from dental sac begins to form what two structures?

Answer 20

Periodontal ligament (PDL) and tooth sockets

Question 21

What is Sharpey’s Fibers

Answer 21

Mineralized ends of PDL; portion that is inserted into the cementum and alveolar process (bone)

Question 22

Define Eruption

Answer 22

Vertical movement of tooth eruption

Question 23

After enamel growth ceases in crown of tooth what occurs?

Answer 23

Ameloblasts place acellular dental cuticle on newly formed outer enamel surface

Question 24

During tooth shedding, what occurs to the layers of enamel organ

Answer 24

The enamel organ condenses into one layer called Reduced Enamel Epithelium (REE)

Question 25

What occurs after REE forms?

Answer 25

Tooth begins eruption into oral cavity

Question 26

Describes the steps of eruption process (2)

Answer 26

1. REE fuses with oral epithelium 2. Enzymes of REE disintegrate central part of the fused tissue - forming the Gubernacular canal

Question 27

What is the Gubernacular Canal?

Answer 27

Protective epithelial-lined eruption tunnel where the tooth erupts through

Question 28

What is the initial junctional epithelium and what does it do?

Answer 28

Fused tissue near the CEJ; creates seal between the tissue and tooth surface

Question 29

What is the initial junction epithelium later replaced by?

Answer 29

Definitive junctional epithelium

Question 30

In what direction do succedaneous permanent teeth develop?

Answer 30

Lingually to primary teeth except permanent maxillary incisors which develop facially

Question 31

What are osteoclasts

Answer 31

absorb alveolar process

Question 32

What are odontoclasts

Answer 32

tooth root resorption; removal of dentin and cementum

Question 33

What is the nasmyth membrane

Answer 33

Green gray residue formed on newly erupted teeth; consists of fused tissue of the REE and oral epithelium