Chapter 8: Tooth Replacement, Mixed Dentition Flashcards
When does tooth replacement or the transition period occur?
Between 6-12 years of age
tooth replacement or the transition period are characterised by:
- the presence of temporary and permanent teeth simultaneously
The 3 stages of tooth replacement or the transition period are:
- mixed dentition 1st stage
- mixed dentition 2nd stage
- 3rd stage
Which dentition (temporary or permanent) has a greater variability in its chronology?
Permanent dentition
Which stage (1st or 2nd) has a greater variability in its chronology?
2nd
What affects the eruption chronology?
- endocrine, prepubescent, and local conditions (trauma)
Mixed dentition 1st stage: what teeth erupt during this stage?
Incisors and 1st molars
Mixed dentition 1st stage: from what ages?
6-9 years old
Mixed dentition 1st stage: eruption sequence with ages:
- 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
Mixed dentition 2nd stage: what teeth erupt during this stage?
Canines, PM, and 2nd molars
Mixed dentition 2nd stage: from what ages?
9-12 years old
Mixed dentition 2nd stage: eruption sequence with ages:
- 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
3rd stage: which teeth erupt during this stage?
3rd molars
3rd stage: from what ages?
18-25 years old
Why is the sequence of eruption very important?
Because it determines the use of the spaces in the arch
Eruption sequence: posterior teeth (2nd stage sequence) of the upper arch: MOST FREQUENT SEQUENCE:
4 (1st PM), 5 (2nd PM), 3 (canine), 7 (2nd molar)
Eruption sequence: posterior teeth (2nd stage sequence) of the upper arch: FREQUENT SEQUENCE:
4 (1st PM) ,3 (canine) ,5 (2nd PM) ,7 (2nd molar)
Eruption sequence: posterior teeth (2nd stage sequence) of the upper and lower arch: UNFAVOURABLE SEQUENCE:
2nd molar before canine or PM will cause a lack of space
Eruption sequence: posterior teeth (2nd stage sequence) of the lower arch: MOST FREQUENT SEQUENCE:
3 (canine), 4 (1st PM), 5 (2nd PM), 7 (2nd molar)
Eruption sequence: posterior teeth (2nd stage sequence) of the lower arch: COMMON SEQUENCE:
3 (canine), 5 (2nd PM), 7 (2nd molar)
Eruption sequence of the mandible:
6 (1st molar), 1(CI), 2 (LI), 3 (canine), 4 (1st PM), 5 (2nd PM), 7 (2nd molar), 8 (3rd molar)
If:
- the CI erupts before the 1st molar
- the 1st PM erupts before the canine
Will this cause significant changes in the mandible?
NO
If:
- the C erupts before the LI
- the 2nd permanent M erupts before the 2nd PM
Will this cause significant changes in the mandible?
YES
If the 2nd permanent molar erupts before the 2nd PM: this will cause a lack of space for the PM
Eruption sequence in the maxilla:
6 (1st molar), 1 (CI), 2 (LI), 4 (1st PM), 5 (2nd PM), 3 (canine), 7 (2nd molar), 8 (3rd molar)
If:
- the CI erupts before the 1st permanent molar
- the canine erupts before the 2nd PM
Will this cause significant changes in the maxilla?
NO
If:
- the 2nd permanent molar erupts before the exfoliation of the 2nd temporary molar
Will this cause significant changes in the maxilla?
YES
What are the dimensional changes associated with teeth replacement in the anterior teeth according to Black?
- 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
Factors that compensate for the lack of space are:
- 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)
What are the dimensional changes associated with teeth replacement in the posterior teeth according to Black?
- 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)
Eruption of 1st lower molar:
- at which age
- direction
- months
- which cusp erupts first
- what must occur for its eruption to take place
- 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
Eruption of 1st upper molar:
- at which age
- direction
- months
- which cusp erupts first
- what must occur for its eruption to take place
- 6 years old
- distal and buccally
- 7-10 months
- bone apposition in the tuberosity will take place to accommodate the molar
Determinants of molar relationship:
- terminal plane (primary molars)
- differential growth of the maxilla-mandible
- leeway space
- eruption sequence
- diastema location
Eruption of lower central incisor
- at which age
- direction
- 6 years old
- erupts lingual and tongue moves them to a buccal position
Eruption of upper central incisor
- at which age
- direction
- speed of eruption
- 7 years old
- buccal
- high speed
Eruption of lower lateral incisors:
- at which age
- direction
- why might they suffer space problems such as rotations
- 7 years old
- erupt more lingual and tongues leads them to buccal
- due to the eruption of the lower canines
Eruption of upper lateral incisors:
- at which age
- direction
- speed of eruption
- 8 years old
- buccal
- slower eruption than central
Usually the upper incisors erupt ____ while the lower incisors erupt ____ and the ____ pushes them back into position?
Buccally
Lingual
Tongue
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 ____
Diastema
Palatal
More complex
Intra-bone position: when do diastemas close?
When lateral incisors erupt
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
- 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
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
- 11 years old
- higher position
- impactation or buccal eruption
The period from 8-12 years old is known as?
Ugly duckling stage
Ugly duckling stage: from 8 years old:
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
Ugly ducking stage: at around 12 years old:
These malpositions and diastemas are corrected by the complete eruption of the upper canines (without performing any orthodontic treatment)
Eruption of lower 1st PM:
- at which age
- direction
- which cusps erupts first
- 10 years old
- perpendicular to the occlusal plane
- buccal cusp
Eruption of upper 1st PM:
- at which age
- its ____ is important for the occlusion
- 9 years old
- interlocking
Eruption of lower 2nd PM:
- at which age
- between 1st PM and 1st M: may ____
- 11 years old
- may lack space
Eruption of upper 2nd PM:
- at which age
- if the 2nd permanent molar erupts before —>
- 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
Eruption of lower 2nd molar:
- at which age
- direction
- which cusp erupts first
- 12 years old
- mesial and lingual like in 1st lower molar
- mesial cusp also like in 1st lower molar
Eruption of upper 2nd molar:
- at which age
- direction
- which cusp erupts first
- 12 years old
- distal and buccal like in upper 1st molars
- mesial cusps
Eruption of lower 3rd molar:
- at which age
- direction
- which cusp erupts first
- problems with
- 15-20 years old
- mesial lingual like in lower 1st and 2nd molars
- mesial cusps also like in lower 1st and 2nd molars
- impactation
Eruption of upper 3rd molar:
- at which age
- direction
- which cusp erupts first
- problems with
- 15-20 years old
- distal vestibular like in upper 1st and 2nd molars
- mesial cusp also like in upper 2nd molar
- impactation
