Chapter 8: Tooth Replacement, Mixed Dentition

Question 1

When does tooth replacement or the transition period occur?

Answer 1

Between 6-12 years of age

Question 2

tooth replacement or the transition period are characterised by:

Answer 2

• the presence of temporary and permanent teeth simultaneously

Question 3

The 3 stages of tooth replacement or the transition period are:

Answer 3

• mixed dentition 1st stage
• mixed dentition 2nd stage
• 3rd stage

Question 4

Which dentition (temporary or permanent) has a greater variability in its chronology?

Answer 4

Permanent dentition

Question 5

Which stage (1st or 2nd) has a greater variability in its chronology?

Answer 5

2nd

Question 6

What affects the eruption chronology?

Answer 6

• endocrine, prepubescent, and local conditions (trauma)

Question 7

Mixed dentition 1st stage: what teeth erupt during this stage?

Answer 7

Incisors and 1st molars

Question 8

Mixed dentition 1st stage: from what ages?

Answer 8

6-9 years old

Question 9

Mixed dentition 1st stage: eruption sequence with ages:

Answer 9

• 6 years old: 1st molars
• 6.5 years old: lower central incisors
• 7 years old: upper central incisors
• 7.5 years old: lower lateral incisors
• 8 years old: upper lateral incisors

Lower B4 upper!!
The only time its upper B4 lower: primary dentition lateral incisors and in permanent dentition PM

Question 10

Mixed dentition 2nd stage: what teeth erupt during this stage?

Answer 10

Canines, PM, and 2nd molars

Question 11

Mixed dentition 2nd stage: from what ages?

Answer 11

9-12 years old

Question 12

Mixed dentition 2nd stage: eruption sequence with ages:

Answer 12

• 9 years old: upper 1st PM + lower canine
• 10 years old: lower 1st PM + upper 2nd PM
• 11 years old: upper canine + lower 2nd PM
• 12 years old: 2nd molars

Question 13

3rd stage: which teeth erupt during this stage?

Answer 13

3rd molars

Question 14

3rd stage: from what ages?

Answer 14

18-25 years old

Question 15

Why is the sequence of eruption very important?

Answer 15

Because it determines the use of the spaces in the arch

Question 16

Eruption sequence: posterior teeth (2nd stage sequence) of the upper arch: MOST FREQUENT SEQUENCE:

Answer 16

4 (1st PM), 5 (2nd PM), 3 (canine), 7 (2nd molar)

Question 17

Eruption sequence: posterior teeth (2nd stage sequence) of the upper arch: FREQUENT SEQUENCE:

Answer 17

4 (1st PM) ,3 (canine) ,5 (2nd PM) ,7 (2nd molar)

Question 18

Eruption sequence: posterior teeth (2nd stage sequence) of the upper and lower arch: UNFAVOURABLE SEQUENCE:

Answer 18

2nd molar before canine or PM will cause a lack of space

Question 19

Eruption sequence: posterior teeth (2nd stage sequence) of the lower arch: MOST FREQUENT SEQUENCE:

Answer 19

3 (canine), 4 (1st PM), 5 (2nd PM), 7 (2nd molar)

Question 20

Eruption sequence: posterior teeth (2nd stage sequence) of the lower arch: COMMON SEQUENCE:

Answer 20

3 (canine), 5 (2nd PM), 7 (2nd molar)

Question 21

Eruption sequence of the mandible:

Answer 21

6 (1st molar), 1(CI), 2 (LI), 3 (canine), 4 (1st PM), 5 (2nd PM), 7 (2nd molar), 8 (3rd molar)

Question 22

If:
- the CI erupts before the 1st molar
- the 1st PM erupts before the canine

Will this cause significant changes in the mandible?

Answer 22

NO

Question 23

If:
- the C erupts before the LI
- the 2nd permanent M erupts before the 2nd PM

Will this cause significant changes in the mandible?

Answer 23

YES

If the 2nd permanent molar erupts before the 2nd PM: this will cause a lack of space for the PM

Question 24

Eruption sequence in the maxilla:

Answer 24

6 (1st molar), 1 (CI), 2 (LI), 4 (1st PM), 5 (2nd PM), 3 (canine), 7 (2nd molar), 8 (3rd molar)

Question 25

If: - the CI erupts before the 1st permanent molar - the canine erupts before the 2nd PM Will this cause significant changes in the maxilla?

Answer 25

NO

Question 26

If: - the 2nd permanent molar erupts before the exfoliation of the 2nd temporary molar Will this cause significant changes in the maxilla?

Answer 26

YES

Question 27

What are the dimensional changes associated with teeth replacement in the anterior teeth according to Black?

Answer 27

- MD diameter of permanent incisors (widest teeth MD, 8) is greater than in primary incisors - difference: 7.6 in the maxilla and 6 in the mandible

Question 28

Factors that compensate for the lack of space are:

Answer 28

- presence of diastemas - a higher buccal inclination of the permanent incisors (125 degrees for permanent teeth and 150 degrees for temporary teeth) - primate spaces - inter canine increased width (by increasing size of the maxilla)

Question 29

What are the dimensional changes associated with teeth replacement in the posterior teeth according to Black?

Answer 29

- the MD diameter of the permanent canine + 1st PM + 2nd PM is smaller than the diameter of the temporary canine + 1st temporary molar + 2nd temporary molar==> leeway space - difference in size: 1.8mm in the maxilla (0.9 on each side) and 3.4mm in the mandible (1.7 on each side)

Question 30

Eruption of 1st lower molar: - at which age - direction - months - which cusp erupts first - what must occur for its eruption to take place

Answer 30

- 6 years old - mesial and lingual - 12-16 months, slower eruption than in single rooted teeth - mesial cusp first - reabsorption of the anterior border of the ramus of the mandible

Question 31

Eruption of 1st upper molar: - at which age - direction - months - which cusp erupts first - what must occur for its eruption to take place

Answer 31

- 6 years old - distal and buccally - 7-10 months - bone apposition in the tuberosity will take place to accommodate the molar

Question 32

Determinants of molar relationship:

Answer 32

- terminal plane (primary molars) - differential growth of the maxilla-mandible - leeway space - eruption sequence - diastema location

Question 33

Eruption of lower central incisor - at which age - direction

Answer 33

- 6 years old - erupts lingual and tongue moves them to a buccal position

Question 34

Eruption of upper central incisor - at which age - direction - speed of eruption

Answer 34

- 7 years old - buccal - high speed

Question 35

Eruption of lower lateral incisors: - at which age - direction - why might they suffer space problems such as rotations

Answer 35

- 7 years old - erupt more lingual and tongues leads them to buccal - due to the eruption of the lower canines

Question 36

Eruption of upper lateral incisors: - at which age - direction - speed of eruption

Answer 36

- 8 years old - buccal - slower eruption than central

Question 37

Usually the upper incisors erupt ____ while the lower incisors erupt ____ and the ____ pushes them back into position?

Answer 37

Buccally Lingual Tongue

Question 38

Intra-bone position: maxilla: Central incisors erupt with a distal angulation resulting in an initial ____ The eruption of the lateral incisors starts from a more ___ position which makes their eruption ____

Answer 38

Diastema Palatal More complex

Question 39

Intra-bone position: when do diastemas close?

Answer 39

When lateral incisors erupt

Question 40

Eruption of lower canines: - at which age - do they usually have eruption problems - in an xray—> in which position is the mandibular canine in comparison to the PM, and why is it in that position

Answer 40

- 9 years old - no, even though they’re usually crowded - mandibular canine is in a lower position than the PM, even though it erupts before, this is because its eruption is faster

Question 41

Eruption of upper canines: - at which age - in an xray—> in which position is the germ compared to the rest of the teeth - frequent problems include

Answer 41

- 11 years old - higher position - impactation or buccal eruption

Question 42

The period from 8-12 years old is known as?

Answer 42

Ugly duckling stage

Question 43

Ugly duckling stage: from 8 years old:

Answer 43

The germ of the upper canine starts to go down touching the roots of the LI and pushing them to mesial, while the crown moves to distal

Question 44

Ugly ducking stage: at around 12 years old:

Answer 44

These malpositions and diastemas are corrected by the complete eruption of the upper canines (without performing any orthodontic treatment)

Question 45

Eruption of lower 1st PM: - at which age - direction - which cusps erupts first

Answer 45

- 10 years old - perpendicular to the occlusal plane - buccal cusp

Question 46

Eruption of upper 1st PM: - at which age - its ____ is important for the occlusion

Answer 46

- 9 years old - interlocking

Question 47

Eruption of lower 2nd PM: - at which age - between 1st PM and 1st M: may ____

Answer 47

- 11 years old - may lack space

Question 48

Eruption of upper 2nd PM: - at which age - if the 2nd permanent molar erupts before —>

Answer 48

- 10 years old - may lack space for its eruption, the 2nd permanent molar would push the 1st molar, closing the space for then 2nd PM

Question 49

Eruption of lower 2nd molar: - at which age - direction - which cusp erupts first

Answer 49

- 12 years old - mesial and lingual like in 1st lower molar - mesial cusp also like in 1st lower molar

Question 50

Eruption of upper 2nd molar: - at which age - direction - which cusp erupts first

Answer 50

- 12 years old - distal and buccal like in upper 1st molars - mesial cusps

Question 51

Eruption of lower 3rd molar: - at which age - direction - which cusp erupts first - problems with

Answer 51

- 15-20 years old - mesial lingual like in lower 1st and 2nd molars - mesial cusps also like in lower 1st and 2nd molars - impactation

Question 52

Eruption of upper 3rd molar: - at which age - direction - which cusp erupts first - problems with

Answer 52

- 15-20 years old - distal vestibular like in upper 1st and 2nd molars - mesial cusp also like in upper 2nd molar - impactation