12. Extractions

Question 1

Know eruption patterns for canines and bicuspids on mandibular and maxillary arch

Answer 1

Maxilla
-1st PM – 2nd PM – canine

Mandible
-Canine– 1st PM– 2nd PM

Question 2

Serial extraction purpose

Answer 2

• Disrupt usual eruption sequence (want the 1st bicuspids on lower arch to come in before canines)
• Extract in early mixed dentition to avoid crowding in permanent dentition
• Facilitates fixed appliance therapy later

Question 3

Contraindications for serial extraction

Answer 3

• Class II or III
• Skeletal discrepancy
• Deep overbite (need maxillary Hawley and baseplate)
• Imbalance perioral musculature (strain, hypo/hypertonicity)
• Habits

Question 4

Want at least _ mm of crowding for serial extractions

Answer 4

10 mm

Question 5

Sequence of serial extractions

Answer 5

• Extract all deciduous canines
• Extract deciduous 1st molars
• Extract 1st bicuspids

Question 6

Why extract the deciduous canines

Answer 6

-eases anterior crowding

Question 7

Extraction of the deciduous first molars benefits the (maxillary/mandibular) arch

Answer 7

mandibular

Question 8

Why extract the 1st bicuspids

Answer 8

-permanent canines drift distally into extraction sites

Question 9

Benefits of serial extractions

Answer 9

• Naturally induced alignment severely crowded anterior teeth
• Improved periodontal health
• Improved cosmetics/psychological state
• Facilitates fixed appliance workload
• Less possible orthogenic damage

Question 10

T/F anchorage units tend to move

Answer 10

t

Question 11

Which is more difficult maintaining tooth position or moving teeth

Answer 11

maintaining

Question 12

Difference between intra-oral and extra-oral anchorage

Answer 12

intra= anchorage inside the mouth 
Extra= outside mouth

Question 13

Cervical, occipital and parietal are…

Answer 13

down, horizontal and high pull

Question 14

Facial includes what extraoral features

Answer 14

forehead and chin

Question 15

Intra-oral anchorage types are

Answer 15

• Simple
• Stationary
• Reciprocal

Question 16

Describe simple, stationary and reciprocal anchorage

Answer 16

• Simple= tooth may tip
• Stationary= tooth may only move bodily (translate)
• Reciprocal= both units move equal amounts in opposite directions

Question 17

Structures for intra-oral anchorage are

Answer 17

• Teeth
• Basal bone and overlying soft tissue
• Cortical bone plates

Question 18

Characteristics of teeth that make good anchors are

Answer 18

• Root form
• Root size and number
• Root length

Question 19

Root form of

• bicuspids
• Mand. incisors
• Canines
• Max. centrals

Answer 19

• bicuspids= round
• Mand. incisors= flat
• Canines= triangular
• Max. centrals= triangular

Question 20

Increased root surface = (increased/decreased) stress resistance

Answer 20

increased

Question 21

Basal bone and soft tissue that can be used for anchorage includes what structures intraorally

Answer 21

• hard palate (i.e nance)

- Lingual surface of mandible

Question 22

T/F cortical plates facilitate tooth movement

Answer 22

f- resists tooth movement. cancellous bone supports tooth movement

Question 23

TADs stands for

Answer 23

temporary anchorage device

Question 24

Another word for TADs is

Answer 24

orthodontic microimplants