Tooth Development Anomalies

Question 1

Define:
Hypodontia
Oligodontia
Anodontia

What is the prevalence of hypodontia?

Answer 1

Hypodontia: Agenesis of 1-6 teeth
Oligodontia: Agenesis of more than 6 teeth
Anodontia: Agenesis of entire dentition

1-10% excluding 8’s; 20% including 8’s

Question 2

What is the prevalence of hyperdontia?

What proportion involve a single tooth?

Answer 2

5% or less
75-85% involve a single tooth
95% in Mx

Question 3

T or F?

Hyperdontia occurs more frequently in permanent dentition?

Answer 3

T

Question 4

What tooth groups do hyperdontia occur most often in?

Answer 4

Mx central incisors> mx and md 4th molars > premolar > canines > laterals

Question 5

What are the types of supernumery teeth?

Answer 5

• Supplemental: Normal size and shape

- Rudimentary: Abnormal size and shape

Question 6

What is gemination?

Answer 6

When two teeth develop out of a single tooth bud, creating a double tooth

Question 7

What is fusion?

Answer 7

When two existing tooth buds merge together, creating a double tooth

Question 8

How do you tell the difference between fusion and gemination?

Answer 8

• In gemination: tooth count normal

- In fusion: tooth count is one less than expected

Question 9

What is the prevalence of fusion and gemination?

Answer 9

Decid (0.5-2.5%)
Perm (0.5%)
Can go up to 5% in Asians
Ant>posterior teeth
Mx>Md

Question 10

What is concrescence?

Answer 10

Union of 2 fully formed teeth at the roots by cementum without merging of dentine. Posterior teeth most often affected (7’s merging with 8’s)

Question 11

What are some non-congenital causes of concrescence?

Answer 11

Gross caries causing excessive reparative cementum production