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Dental Morphology > Anatomy of Primary Teeth > Flashcards

Anatomy of Primary Teeth Flashcards

1
Q

What are the typical characteristics of primary central incisors (MX and MN) that differ from the permanent set?

A

Mamelons are not visible
The CEJ is squashed- creating a labial and lingual bulge called a cervical constriction

The roots are round in cross section, but not often seen because they are reabsorbed

MX: M→D is equal or wider than C→I dimension = short and wide crown. M-I angle is sharper, D-I is more round and blunt. Also a shallow lingual fossa.

MN: Crown flares a lot. With M→ D blunt/round

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2
Q

What is the developmental sequence for Central Incisors and Lateral Incisors?

A

Central: MN proceeds MX

1st calc = 4 months in utero (Lateral: 4.5 months in utero)

Emerge = 8-10 months (Lateral: 9-13 months)

Exfoliate = 6-7 years (Lateral: 7-8 years)

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3
Q

What are the typical characteristics of the Lateral Incisors (MN and MX)?

A

MX: Labial is smaller than 5,1.

MN: Labial is more flared distally= bigger than 7,1

Root = compressed M→D = oval in cross section

No mamelons

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4
Q

What is the developmental sequence of canines MX and MN?

A

1st calc = 5 months utero

Emergence = 18 months

Exfoliation = 12 years MX, 9 years MN

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5
Q

What are the distinguishing characteristics of the MX vs MN canines?

And how does the root differ to the incisors?

A

Crown Labial:

MX= Shorter and bulbous

*mesial cusp slope is longer than distal = pointy sharp cusp tip

MX = longer than MX

*mesial slope shorter than distal

Roots are long, more triangular that central and laterals.

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6
Q

What are the main distinguishing features of the primary anterior teeth compared to permanent anterior teeth?

A
  • Smaller and whiter
  • Crowns are wider M→D than C→I (permanent teeth are longer and narrower)
  • Prominent cervical ridge (bulge at CEJ) - due to cervical constriction.
  • Roots are longer and slender
  • No mamelons present incisors
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7
Q

Describe the Mx 1st primary molar (5, 4)

A
  • 4 cusps, MP is the tallest and sharpest, DP can be missing
  • 2 fossae, central and medial- linked by developmental groove.
  • 3 roots- splayed
  • May have oblique ridge linking MP→DB
  • CEJ- cervical constriction = buccal bulge
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8
Q

Describe the roots of the MX primary molars

A

X3 roots= M + D root (buccal) and 1 palatal which is the longest

Roots are more splayed in second molar.

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9
Q

Describe the MX 2nd Primary Molar (5,5) and compare it to the MX 1st Permanent Molar (1,6)

A
  • It is larger than 1st MX molar.
  • Cusps are sharper and smaller than in 1,6.
  • MP cusp is biggest and has oblique ridge DB→MP like 1,6
  • Marked cervical bulge constriction= pronounced on buccal aspect
  • May have tubercle on MP cusp
  • Root trunk is short and 1 root canal. Root gets reabsorbed.
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10
Q

What are the differences between MX primary 1st molar and MX permanent 1st molar?

A
  • Pronounced cervical constriction = buccal bulge
  • Root trunk is smaller
  • Roots are longer and slender, more splayed
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11
Q

What are the differences between MX primary 1st molar and MX 1st premolar?

A
  • Cervical constriction- buccal bulge
  • Primary has 3 roots that are more splayed, not 2 roots.
  • Primary has 4 cusps, not 2 cusps
  • Primary may have oblique ridge
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12
Q

Identify this primary molar and describe its typical features

A

Mandibular 1st Primary Molar- (7,4)

  • Most unique looking tooth,
  • 4 cusps, Mesial crown is high - MB cusp and MP cusp (sharper) are both more developed
  • *Noticeable buccal curve/bulge at cervical ⅓ → CEJ dips apically at mesial root.
  • ZigZag developmental groove
  • Roots are often twice as long as crown, flare and short root trunk
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13
Q

When do mandibular molars erupt?

A

After lower incisors, skips canines

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14
Q

Describe the MN 2nd Primary Molar

A

7.5

  • Much larger than 7,4.
  • Resembles MN permanent 1st molar - though crown is rounder
  • Cervical constriction- bulge
  • 5 cusps, (x3 buccal cusps like 3,6)
  • 2 roots
  • Roots are twice as long as crown, flare and short root trunk
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15
Q

What are the main differences between primary vs permanent molars?

A
  • Predecessors of premolars, though morphologically more similar to permanent molars = 2nd primary molar MX has oblique ridge like 1,6. 2nd primary molar MN has 3 buccal cusps like 3,6.
  • Constricted cervical region = buccal bugle
  • Roots twice as long as crown, more flared
  • Roots undergo resorption
  • Pulpal forms are higher
  • Enamel is thinner and more consistent in thickness
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16
Q

Draw and compare Central incisors MN and MX

A
17
Q

Draw and compare lateral incisors MN and MX

A
18
Q

Draw and compare upper and lower canines

A
19
Q

Draw MX Primary 1st Molar and Permanent 1st Molar FROM Proximal view

A
20
Q

Draw occlusal view of MX 1st and 2nd Molars

A
21
Q

Draw the proximal and occlusal view of MN 1st and 2nd molars

A
22
Q

What is the Leeway Space of Nance?

A

Premolars are smaller than primary molars for space, to prevent crowding in mixed dentition. Specifically, 1st permanent molar will move mesially-

1.5 mm for MX

and 2.5 mm for MN

23
Q

When do teeth finish erupting?

A

2.5 years

24
Q

What is the importance of primary teeth?

  • list 4 things
A
  • Growth and development of muscles of mastication + Bones of MN and MX
  • For location, alignment and occlusion of permanent dentition
  • For speech
  • For eating
25
Q

What is the emergence generally of primary teeth?

A

6-8 months to 2.5 years

26
Q

What is exfoliation and where does it begin?

A

The shedding of primary dentition.

Begins at the apical end of the tooth root- resorption.

The root is resorbed- tooth root structure is taken back by the body.

27
Q

What are the main differences between morphology of primary and permanent teeth?

x6

A

Primary teeth:

  • enamel and dentin is thinner
  • whiter in colour
  • broad and flat contact areas
  • Cervical constriction- bulge prominent
  • Smaller overall size
  • Narrower roots- more splayed
  • Enamel rods in cervical area are directed occlusally, compared to cervically in permanent
28
Q

How does the cavity preparation Class 2 restoration in primary teeth differ to permanent teeth?

What other structure do you need to consider in primary teeth?

A

In primary teeth enamel rods in cervical area are directed occlusally, compared to cervically in the permanent teeth.

Pulp cavity. Because pulp has a higher volume and enamel and dentine is thinner- therefore it’s easier to get to with caries .

29
Q

Draw and identify the visual differences between primary and permanent molars

A
30
Q

Why can you sometimes see the permanent tooth directly as primary tooth exfoliates?

A

Resorption of primary teeth (root) guides the succedaneous tooth into correct alignment.

The tooth can follow the resorbing root until the primary tooth exfoliates

Dental Morphology (5 decks)

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