Radiographs and caries in primary molars

Question 1

Describe the anatomy of primary molars

Answer 1

Thin, uniform 1mm thickness of enamel
Smaller crowns and marked constriction
Narrow occlusal table
Broad contact areas

Question 2

What are the uses of primary molars?

Answer 2

Facilitate development of the facial muscles
Guide for secondary tooth eruption

Question 3

What is the anatomy of the pulp of a primary molar?

Answer 3

Large pulp, follows external contours of the teeth

Large mesio-buccal pulp horn (pulp horn is higher)

Thin pulpal floor

Early radicular pulp involvement

Question 4

What is the anatomy of a permanent molar?

Answer 4

Variable thickness of enamel
Thicker layer of dentine
Proportionally smaller pulp

Question 5

How does the anatomy of a primary tooth affect caries progression?

Answer 5

-Rapid caries progression
-Short clinical crown - difficult to place a matrix band
-Need to restore broad contact points
-Thin enamel with less tooth structure protecting the pulp
- Mesio-buccal pulp horn easily exposed
- Long, flared roots therefore pulpectomy is difficult

Question 6

How many more times is a radiograph likely to detect caries in adults and children?

Answer 6

4x in adults
Children 8x

Question 7

What is the radiation risk to a child less than 10 years of age

Answer 7

x3 compared to a 30y/o adult

Question 8

Why is the radiation risk higher in children?

Answer 8

Tissues are more radiosensitive and lifespans are longer

Children are 2-3x more at risk of developing radiation induced cancer than adults in their 30s for the same effective dose

ALARP

Question 9

High risk repeat radiographs

Answer 9

6 months

Question 10

Moderate risk repeat radiographs

Answer 10

1y

Question 11

Low risk repeat radiographs

Answer 11

12-18m in primary dentition
2y in mixed dentition

5y/o - 3y
8-9 y/o - 3-4y
12-16 y/o - 2 y
16 y/o - 3 y

Question 12

Indications for radiographs

Answer 12

Detection of interproximal caries
Dental trauma
Disturbances on tooth development and growth
Pathological conditions

Question 13

Pratical tips for radiograph taking:

Answer 13

size 0 fit or phosphor plate with a tab for children 4-7

size 0 film with phosphor plate in holder for 7-10

size 2 or phosphor plate with a holder for children with mixed dentition ages 10-11 and when the second molar erupt at age 12

Question 14

What is the bisecting angle technique?

Answer 14

Place film flat in occlusal plane and bisecting angle of tube head. (deciduous incisors)