Shedding and Replacement

Question 1

What are the 3 physiological tooth movements to bring teeth into the occlusal plane?

Answer 1

1. Pre-eruptive
2. Eruptive
3. Post-eruptive

Question 2

How is pre-eruptive movement made?

Answer 2

Deciduous and permanent tooth germs

Question 3

How is eruptive tooth movement made?

Answer 3

Tooth moving from its position in jaw to functional position in occlusion

Question 4

How is post-eruptive tooth movement made?

Answer 4

Maintenance of the position of erupted tooth in occlusion while jaw grows

Question 5

What is the first stage of pre-eruptive tooth movement?

Answer 5

Tooth germs grow rapidly and become crowded

Question 6

What is the second stage of pre-eruptive tooth movement?

Answer 6

Jaws lengthen so deciduous 2nd molar tooth germs move backward and alleviate crowding

Question 7

What is the third stage of pre-eruptive tooth movement?

Answer 7

Permanent tooth germs develop on the lingual aspect of deciduous predecessors

Question 8

Where do the incisor and canine permanent tooth germs occupy?

Answer 8

Position on the lingual side of roots of their deciduous predecessors

Question 9

Where do the premolar permanent tooth germs occupy?

Answer 9

Position between the divergent roots of the deciduous molars

Question 10

Where do the maxillary molar permanent tooth germs occupy?

Answer 10

Occlusal surfaces face distally and swing into position when the maxilla has sufficiently grown

Question 11

Where do the mandibular molar permanent tooth germs occupy?

Answer 11

Axes show a mesial inclination which becomes vertical when the mandible has sufficiently grown

Question 12

Where does pre-eruptive tooth movement occur?

Answer 12

Interosseous location

Question 13

What are 2 main changed which occur during eruptive tooth movement?

Answer 13

1. Tooth moves from its developmental position in jaw to final position in occlusal plane
2. Fibres of the periodontal ligament are remodelled

Question 14

How do the fibres of the periodontal ligament remodel?

Answer 14

Fibroblasts simultaneously synthesise and degrade collagen fibrils as required

Question 15

How does the dental follicle of permanent teeth retain connection with lamina propria of oral mucosa?

Answer 15

Gubernacular cord

Question 16

What is the gubernacular cord composed of?

Answer 16

Fibrous tissue containing epithelial remnants of the dental lamina

Question 17

What is the gubernacular canal?

Answer 17

Eruptive pathway of a tooth

Question 18

Name a type of factor which influences and determines a tooth’s final position in the dental arch

Answer 18

Environmental

Question 19

Name 2 types of environmental factors which help determine the tooth’s final position in the dental arch

Answer 19

1. Muscle forces from tongue, cheeks and lips

2. Forces of contact from other erupting teeth

Question 20

What are the 3 categories that post-eruptive tooth movement can be divided into?

Answer 20

1. Movement to accommodate growing jaws
2. Compensation for occlusal wear
3. Accommodation for interproximal wear

Question 21

What are post-eruptive tooth movements?

Answer 21

Movements that are made by the tooth after it has reached its function position in the occlusal plane

Question 22

How does tooth position readjustment to accommodate for growth of jaws occur?

Answer 22

Formation of new bone at the alveolar crest and the socket floor

Question 23

How is compensation for occlusal wear achieved?

Answer 23

1. Additional cementum is produced around the apex of the tooth after movement occurs

Question 24

How is accommodation for interproximal wear achieved?

Answer 24

Mesial drift

Question 25

Where does the resorption of deciduous incisors and canines occur?

Answer 25

Lingual surface

Question 26

What is the major difference between the resorption of deciduous incisors and canines and deciduous molars?

Answer 26

Much more resorption occurs in the deciduous molars, with pulp chamber, coronal dentin and sometimes enamel being resorbed

Question 27

What cells resorb deciduous teeth?

Answer 27

Odontoclasts

Question 28

From where are odontoclasts derived?

Answer 28

Monocytes

Question 29

How do fibroblasts die during the shedding of teeth?

Answer 29

Apoptosis

Question 30

What can delay the shedding of a tooth?

Answer 30

If the successional tooth is missing