Postnatal Development of the Human Dentition Flashcards

1
Q

During the 9-11 years of development (from 3-12/14 yrs of age), what should the dentist look out for need for intervention?

A
  1. Recognising developmental anomalies
  2. Recognising disruptions to the normal development of the dentition
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2
Q

What are the basic knowledge principles in post-natal dental development?

A
  1. Sequence and Timing of eruption
  2. Leeway space
  3. Root development and emergence of teeth

PLUS Observations of developing dental conditions

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3
Q

What observations should warrant investigations and/or treatment?

A
  1. Delayed (>6 months past normal range of eruption) and disturbance of eruption of permanent teeth (unilateral)
  2. Difference in occlusal plane between posterior and anterior teeth –> possible thumb sucking?
  3. Marked displacement of teeth (unilateral) eg. misalignment
  4. Prolonged retention of primary teeth (unilateral or bilateral)
  5. Premature loss of primary teeth (unilateral or bilateral)
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4
Q

What is the normal eruption sequence of Primary teeth?

A

A, B, D, C, E

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5
Q

At which stages is there an increase in arch length (depth) + width in a child’s jaw

A

Birth
6-8 months
9-10 months

24-30 months
30-72 months

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6
Q

At which stages is the arch length (depth) and width of a child stabilized?

A

10-14months
14-18 months
18-24 months

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7
Q

What is the eruption timing and sequence of children

A

Birth: NIL
6-8 months: 1/2 As (lower)
8-10 months: As
10-14 months: Bs
14-18 months: Ds
18-24 months: Cs
24-30 months: Es
30-72 months: NIL

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8
Q

What is the clinical advantage of having spaced deciduous dentition over the closed dentition?

A

Spaced dentition results in better outcome in permanent dentition eruption as it allows larger permanent dentition to erupt without problems.

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9
Q

What is the percentage of children with spaced deciduous dentition and closed deciduous dentition.

A

Spaced: 75%
Closed: 25%

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10
Q

What is the normal first three permanent teeth to erupt?

A

6, 1, 2

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11
Q

What is the eruption timing and sequence of the first 3 permanent dentitions?

A

5-6 yrs: 6s
6.2yrs: lower 1s start
7yrs: lower 1s completed, upper 1s start
7.3 yrs: lower 2s begins
8 yrs: upper 1s and lower 2s completed, upper 2s begins
8.5 yrs: upper 2s completed

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12
Q

What does an ectopic mesial eruption of #16 cause?

Tx?

A

External root resorption of E distal

Most self correcting (66%)
If severe then extract and preserve space.

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13
Q

What are the observations in the ectopic eruption of a molar?

A

Unilateral delayed eruption and difference in occlusal plane (E becomes overerupted)

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14
Q

What factors to consider to resolve impaction of teeth

A
  1. Root formation completion: incomplete = good potential for tooth eruption
  2. Curvature of root: Substantial root curvature makes proper tooth positioning impossible as it can hit cortical bone easily if it is tracked
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15
Q

What is the value of a CBCT

A
  1. Visualize the true extent of displacement
    2.Stage of root formation and development of dilaceration
  2. Ability to plan with oral surgeon best approach and position of attachment to be bonded to the crown
  3. Increased understanding from parents after visualization and explanation on severity of displacement
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16
Q

What is seen on the fingers in digit sucking habit patients

A

Callous formations

17
Q

What is the period between early and late mixed dentition stage and what changes happen then

A

8.5 - 9.8 years old

Nothing!

18
Q

What is the eruption sequence of permanent teeth (late mixed dentition)

A

U = 4, 5, 3, 7
L = 3, 4, 5, 7

19
Q

What is the eruption timing and sequence of the last 4 permanent dentitions?

A

9.8 yrs: lower 3s begin
10-10.5 yrs: lower 3s completed, 4s begin
11-11.5 yrs: 4s completed, 5s begin
11.5-12 yrs: 5s completed, upper 3 begins
12 yrs: upper 3 completed

20
Q

What is Leeway space

A

Leeway space (mm) = CDE - sum of 345

21
Q

What are the two principles of root development and emergence of tooth?

A
  1. There is no vertical eruptive movement of dental crypt within the alveolar bone until half of root is formed
  2. Crown emerges through the alveolar bone with 3/4 root formation
22
Q

What is the average time needed for root development from 25-50% (no movement of crypt) for 3, 4, 5

A

Canine: 2.25 yrs
First premolar: 1.5 years
Second premolar 1.5 yrs

23
Q

What is the average time needed for root development from 50-75% (eruption of crown) for 3, 4, 5

A

1.5 years

24
Q

Why is the average time needed for root development information important?

A

To determine when and for how long to place in a space maintainer.

25
Q

What is the consequence of early loss of primary 2nd molar and with no space maintained?

A

mesialisation of 6 –> inadequate space for eruption of 5

26
Q

How long should a space maintainer be placed if the root formation of the 4 is at 1/4 or <1/4 and the E is extracted?

A

1.5 yrs + 1.5 yrs = 3 yrs