Tooth Development and Eruption

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Questions and Answers

What is the characteristic of the canine crown from the labial aspect?

The mesial slope of the cusp is longer than the distal slope

The crown is more constricted at the cervical area (correct)

The crown appears narrower mesiodistally

The crown is thicker labiolingually because of the short crown’s length

How many roots does the permanent first molar have?

Five roots: mesial, distal, lingual, buccal, and supplemental roots

Four roots: mesial, distal, lingual, and buccal roots

Two roots: mesial and distal roots

Three roots: lingual, mesiobuccal, and distobuccal roots (correct)

What is the characteristic of the mandibular deciduous central and lateral incisors?

They are narrower mesiodistally in relation to their length

They have a larger root: crown ratio

They have a smaller root: crown ratio

They are wider mesiodistally in relation to their length (correct)

How many cusps does the permanent first molar have?

Four cusps Signup and view all the answers

What is the characteristic of the mandibular deciduous canine?

The labiolingual dimension is much less than the maxillary deciduous canine Signup and view all the answers

What is the characteristic of the permanent first molar from the mesial aspect?

The crown appears thicker labiolingually because of the short crown’s length Signup and view all the answers

How many deciduous teeth are there in total?

20 Signup and view all the answers

What is the characteristic of the deciduous teeth compared to the permanent teeth?

They are smaller in all dimensions Signup and view all the answers

What is the primary function of deciduous teeth in terms of mastication?

To allow proper chewing and grinding of food Signup and view all the answers

At what age does the eruption of deciduous teeth start?

6.5 months Signup and view all the answers

What is the sequence of tooth development stages?

Bud, cap, bell Signup and view all the answers

What happens to the roots of deciduous teeth after eruption?

They start to resorb Signup and view all the answers

What is the significance of deciduous teeth in terms of esthetics?

They enhance the appearance of the face Signup and view all the answers

At what age is the eruption of deciduous teeth complete?

20-30 months Signup and view all the answers

What is the characteristic of the mesiodistal width of maxillary deciduous central and lateral incisors?

It is more than the labiolingual dimension Signup and view all the answers

What is the significance of deciduous teeth in phonetics?

They are essential for speech development Signup and view all the answers

Study Notes

Tooth Development

Tooth development occurs within the bone in the jaw and passes through stages named according to their shapes: Bud stage, Cap stage, and Bell stage.
After the root and crown are formed, the tooth penetrates the mucous membrane and enters into the mouth by a process called “eruption”.

Eruption of Deciduous Teeth

Sequential order of deciduous teeth according to their eruption times:
- Mandibular central incisors: 6.5 months
- Mandibular lateral incisors: 7 months
- Maxillary central incisors: 7.5 months
- Maxillary lateral incisors: 8 months
- Mandibular first molars: 12-16 months
- Maxillary first molars: 12-16 months
- Mandibular canines: 16-20 months
- Maxillary canines: 16-20 months
- Mandibular second molars: 20-30 months
- Maxillary second molars: 20-30 months

Deciduous Teeth

Deciduous teeth are 20 in number.
They start erupting at 6.5 months (mandibular central incisor) and finish at 20-30 months (mandibular and maxillary second molars).
Importance of deciduous teeth:
- Allow proper mastication
- Prevent malocclusion
- Guide the eruption of permanent teeth
- Esthetics
- Phonetics
Deciduous teeth roots are fully formed after eruption, then resorption occurs until exfoliation and eruption of permanent successor teeth.

Maxillary Deciduous Teeth

Central and Lateral Incisors:
- Mesiodistal width is more than labiolingual dimension
- Root: crown ratio is increased
- Crown appears thicker from the mesial aspect due to short crown length
Canine:
- Crown is more constricted at the cervical area from the labial aspect
- Mesial slope of the cusp is longer than the distal slope
- Mesial and distal contact areas are at the same level
- Root: crown ratio is increased
- Crown appears thicker labiolingually due to short crown length
First Molar:
- Four cusps: mesiolingual (largest), mesiobuccal, distobuccal, and distolingual (smallest)
- Three roots: lingual, mesiobuccal, and distobuccal
Second Molar:
- Five cusps: mesiolingual (largest), mesiobuccal, distobuccal, distolingual, and supplemental cusp
- Three roots: lingual, mesiobuccal, and distobuccal

Mandibular Deciduous Teeth

Central and Lateral Incisors:
- Wider mesiodistally in relation to length than permanent mandibular incisors
- Root: crown ratio is increased
- Labiolingual width appears more due to short crown length
Canine:
- Labiolingual dimension is much less than maxillary deciduous canine
- Cervical ridge is less pronounced than maxillary deciduous canine
- Distal slope of the cusp is larger than the mesial slope
First Molar:
- Four cusps: mesiolingual (largest), mesiobuccal, distobuccal, and distolingual (smallest)
- Two roots: mesial and distal
Second Molar:
- Five cusps: mesiolingual, mesiobuccal, distobuccal, distolingual, and distal cusp
- Two roots: mesial and distal