Tooth Eruption Dates

Question 1

How many roots does each tooth usually have?

Answer 1

1 root: Most permanent teeth

2 roots: Maxillary first premolars and mandibular molars

3 roots: Maxillary molars

Question 2

What are the 3 growth periods?

Answer 2

1: 0-6 years - rapid growth
2: 6-12 years - medium growth
3: 12-18 years - slow growth

Question 3

What occurs during the 1st growth phase?

Answer 3

Teeth appear at 6 months

Primary completion at 2.5 years

Question 4

What occurs during the 2nd growth phase?

Answer 4

1. Shedding & replacement of primary teeth with permanent teeth
2. Eruption of 1st permanent molar behind primary molars at 6 years
3. Eruption of 2nd permanent molar behind 1st permanent molar at 12 years

Question 5

What occurs during the 3rd growth phase?

Answer 5

Slow expansion of jaw to accommodate the third permanent molar.

Question 6

What is the general order of tooth eruption?

Answer 6

Lower before upper

Front before back

Question 7

What is the order of eruption in primary teeth?

Answer 7

(6 months to 6 years)

incisors: 6-9 Months
lower central —> lower lateral incisors and upper central incisors —> Upper lateral incisors.

1st Primary molars: 1-1.3 years
Lower first molars —> upper first molars

Canines: 1.5 years
Lower canine —> upper canine

2nd primary molars: 1.75-2.5 years
Lower 2nd molar —> upper 2nd molar

Question 8

What is the order of eruption in permanent teeth?

Answer 8

(6 years to 12 years)

Incisors: 6 to 8.5 years

premolars: between 10-12 years
lower 1st premolar —> upper first and lower 2nd premolar —> Upper 2nd premolar.

Canines are less predictable:
lower = 9.25-10.5 years
= upper 10-11.5 years.

1st permanent molar = 6 years
2nd permanent molar = 12 years

Question 9

When is permenant dentition completed by?

Answer 9

17-21 when 3rd permanent molar erupts

Question 10

What is Calcification & dates

Answer 10

First radiographic appearance of crown - (first evidence of tooth, dark area = no mineral)

Primary teeth: 4-6 months in utero from front to back

Permanent teeth:

• First molars just before birth
• incisors 3-5 months except upper lateral (1 year)
• Canines 6.5 months (lower) and 9 months (upper)
• Premolars 1.85-2.65 years
• Second molars by 3 years
• third molars by 8 years

Question 11

How can you calculate crown completion?

Answer 11

halfway between calcification and eruption

Question 12

Root bifurcation

Answer 12

Lower 1st molar: 4.5 years
Lower 2nd molar: 8.5 years

root of a tooth splits into two forks beneath the pulp chamber

Question 13

When are the roots of the teeth completed?

Answer 13

Primary Teeth: 1-1.5 years after eruption

Permanent teeth: Less than 2 years (lower incisors) to more than 3 years (1st molars) after eruption