Class 1 Prep

Question 1

What is the outline form of the mandibular first molar?

Answer 1

Follows the central developmental groove into the buccal and lingual grooves and the mesial and distal pits

Question 2

How is the outline form shaped

Answer 2

The outline form is “Y-shaped” around the distal cusp and “bow shaped” or “dog bone like” on the mesial cusp with extensions into the buccal and lingual grooves around corresponding cusps

Question 3

What is the outline form?

Answer 3

The shape or form that determines the extent of the cavity.
How wide?
How deep?
How long?

Question 4

What are three factors that determine outline form?

Answer 4

• Direct penetration of micro-organisms and acids
• Spread of decay along the DEJ
• Extension made along fissures and into grooves to insure smooth margins

Question 5

Describe outline form of first molar?

Answer 5

• Extends along the central groove into the fissures
• 1.5mm away from the external marginal ridge
• Mesial and Distal walls diverge toward the occlusal [for parallel enamel rods]
• Depth is 0.5mm into dentin [on real teeth] and 1.5-2.0 on plastic
• The internal line angles are rounded
• The isthmus width is 1.5-2.0 or no greater than 1/4 the intercuspal distance (distance between buccal and lingual grooves)

Question 6

Which statement is resistance or retention:

Buccal and lingual walls converge toward the occlusal

Buccal and lingual walls converge toward the occlusal to form a 90 degree CSA

Answer 6

Buccal and lingual walls converge toward the occlusal to form a 90 degree CSA= RESISTANCE

Buccal and lingual walls converge toward the occlusal= RETENTION

Question 7

What is resistance form?

Answer 7

Shape and placement of the preparation walls that best allow tooth structure and restoration to withstand fracture and masticatory forces

Question 8

What are the resistance forms for a mandibular first molar?

Answer 8

• Flat pulpal floor
• Preserve cuspal inclines and marginal ridges
• Rounded internal line angles
• Divergence of mesial and distal walls
• Pulpal floor depth is 1.5-2.0mm into dentin

Question 9

What is retention form?

Answer 9

Shape or form of cavity prep that prevents displacement or removal of restoration by tipping or lifting forces

-buccal and lingual walls converging occlusally

Question 10

How is remaining decay removed?

Answer 10

Spoon excavator

Round bur

Question 11

When or where do you bevel amalgam preparations?

Answer 11

Gingival and cervical margins: butt joint margins of enamel and amalgam approximating 90 on the occlusal surfaces

Enamel rods are inclined in an apical direction in permanent teeth

Question 12

Steps of preparation

Answer 12

Outline Form
Resistance Form
Retention Form
Convenience Form
Removal of Remaining Decay
Finishing Enamel Walls
Toileting of Cavity

Question 13

What bur is used mostly for amalgam prep and why

Answer 13

Bur 330, pear shaped because its length is approximately 1.5mm

Question 14

Where do you begin cutting?

Answer 14

Central pit

Question 15

If the mesial and distal pits are carious, where do you begin cutting? Why?

Answer 15

Distal pit for visibility