Lecture 5 Tooth Movement

Question 1

What are the 3 ways tooth movement is categorized?

Answer 1

preeruptive, eruptive, posteruptive

Question 2

Which tooth movement is made by the deciduous and permanent teeth within tissues of the jaw before they begin to erupt?

Answer 2

preeruptive tooth movement

Question 3

Which tooth movement is made by a tooth to move form its position within the bone of the jaw to its functional position in occlusion? This phase is sometimes subdivided into intraosseous and extraosseous components.

Answer 3

eruptive tooth movement

Question 4

Which tooth movement maintains the position of the erupted tooth in occlusion while the jaws continue to grow and compensate for occlusal and proximal tooth wear?

Answer 4

posteruptive tooth movement

Question 5

What are the two factors of preeruptive tooth movement?

Answer 5

total movement of the tooth (bodily movement) and growth of one part of the tooth while the rest of the tooth remains fixed

Question 6

T/F During tooth development, alveolar bone grows down towards the dental lamina and grows around the developing deciduous and successional teeth.

Answer 6

False. The alveolar bone grows UP towards the dental lamina.

Question 7

What does introosseous mean?

Answer 7

Occurs within bone

Question 8

What type of growth causes only bone resorption to accommodate the change in shape of the tooth as it grows?

Answer 8

eccentric growth

Question 9

What kind of canals are cords of fibrous tissue that connect the tooth follicle to the lamina propria of the oral muscosa?

Answer 9

gubernacular canals

Question 10

What do gubernacular canals often contain?

Answer 10

cellular remnants of the dental lamina

Question 11

During tooth eruption, what kind of cells widen a canal through the bone producing an eruptive pathway as seen in the dried bone specimen?

Answer 11

osteoclasts

Question 12

T/F Successional incisors and canines erupt facially to the deciduous teeth.

Answer 12

False. Successional incisors and canines erupt LINGUALY to the deciduous teeth.

Question 13

What are the 3 proposed mechanisms of eruptive tooth movement?

Answer 13

root formation, alveolar bone remodeling, PDL formation

Question 14

T/F Root formation is a not a cause of eruption.

Answer 14

True. Even when rootless teeth erupt, some teeth erupt a greater distance than the total length of their roots.

Question 15

T/F When a tooth is removed or replaced with a replica without disturbing the dental follicle, an eruptive pathway still forms within the bone overlying the tooth.

Answer 15

True

Question 16

T/F If a developing tooth is replaced by a metal or silicone replica without disturbing the dental follicle, the replica will not erupt.

Answer 16

False. The replica will erupt.

Question 17

T/F Dental follicle and certain cell-signaling molecules are involved with bone remodeling and will cause eruption.

Answer 17

False. It will not cause eruption. Bone resorption over the tooth clears the path for the tooth but it doesn’t move the tooth.

Question 18

T/F PDL formation is the best theory for eruptive teeth.

Answer 18

True. PDL fibroblasts exhibit significant traction power and have a cytoskeleton that enables them to contract. Since they are well-anchored and can generate significant motive forces they probably contribute to eruptive tooth movement.

Question 19

T/F Resorption of deciduous teeth roots occurs primarily on the lingual surface.

Answer 19

True.

Question 20

What is the name of the cells that remove dental tissue by resorption of dental hard tissue and is historically identical to osteoclasts?

Answer 20

odontoclasts

Question 21

What type of cells are derived from circulating monocytes that develop into macrophages and migrate into the resorption site where they fuse to form the characteristic multinucleated cells with an active ruffled border?

Answer 21

odontoclasts

Question 22

What type of tooth movement is made by the tooth after it has reached its functional position int he occlusal plane?

Answer 22

posteruptive tooth movement

Question 23

What are the 3 reasons of posteruptive tooth movement?

Answer 23

accomodation for growth, compensation for continued occlusal wear, and accomodation for interproximal wear.

Question 24

Which reason of posteruptive tooth movement happens when a tooth socket remodels between the ages of 14-18 forms new bone at the alveolar crest and on the socket floor to keep up with the increasing height of the jaws?

Answer 24

accomodation for growth

Question 25

Which reason of posteruptive tooth movement has axial movement to compensate for wear is probably achieved by the same mechanism as eruptive tooth movement?

Answer 25

compensation for continued occlusal wear

Question 26

Which reason of posteruptive tooth movement has mesial drift that compensates for wear on the points of contact between teeth?

Answer 26

accommodation for interproximal wear

Question 27

What are the mechanisms of accommodation for interproximal wear?

Answer 27

contraction of the transseptal ligament between teeth, soft tissue pressure, and the anterior component of occlusal force

Question 28

T/F Plasticity of the PDL and alveolar bone makes orthodontic tooth movement possible.

Answer 28

True

Question 29

Which type of cells differentiate and reabsorb alveolar bone on the pressure (compression) side of the socket?

Answer 29

osteoclasts

Question 30

What is the process called when PDL undergoes loss of cells from an area of the ligament due to trauma?

Answer 30

hyalinization

Question 31

Which type(s) of cells remodel bone and PDL on the tension side of the socket?

Answer 31

osteoblasts and fibroblasts

Question 32

T/F Cementum is affected by light forces.

Answer 32

False. Cementum should not be affected by light forces because cementum resists resorption more than bone.

Question 33

What is the result of rapid movement that can damage root canal vessels?

Answer 33

pulp necrosis

Question 34

What initiates resorption of the root?

Answer 34

pressure from the erupting successional tooth