Cavity design

Question 1

Why drill a hole?

Answer 1

To remove caries and to help make a restoration

Question 2

What are the reasons for not cutting a cavity?

Answer 2

• Natural tooth tissue is finite
• No restorative material is truly adequate to replace it
• Rebuilding a tooth is complex and time consuming
• A cavity always weakens a tooth
• Replacing a restoration always enlarges a cavity

Question 3

What are the basic objectives of restoring a cavity?

Answer 3

• Remove al bacteria
• Stop marginal fracture or tooth or material
• Resist displacement of material
• Retain material in the tooth
• Prevent further decay
• Remove minimal tooth tissue to achieve these objectives

Question 4

What are the problems with Amalgam?

Answer 4

• Does not bond to tooth tissue
• relatively rigid
• not antibacterial
• brittle

Question 5

What does marginal integrity mean?

Answer 5

How well the enamel is supported at the edges of the restoration

Question 6

Where should margins be placed?

Answer 6

In a cleansable area

Question 7

What instrumentation is used when restoring a cavity?

Answer 7

Burs - diamond and TC

hand instruments - excavators, chisels, marginal trimmers

Question 8

What are the key principles of restorations?

Answer 8

• Margins must be caries fee
• Follow caries rather than rigid design principles
• Use properties of contemporary materials
• use prevention to reduce caries

Question 9

What is amalgam good for?

Answer 9

Smaller cavities, rounded internal angles, bonding by enhancing the marginal seal to increase retention

Question 10

What are the pros and cons of glass ionomers?

Answer 10

Good bond to dentine
retained without mechanical features
can have dished cavities

mechanically weak - wear and fracture

Question 11

What is ART?

Answer 11

Atraumatic restorative treatment - manages caries where there is no electricity with the help of hand exaction and GIC restoration

Question 12

How does ART work?

Answer 12

Need a caries free ADJ

remove unsupported enamel

pack adhesive restoration in - sticky

Question 13

What are fissure sealants reliant?

Answer 13

Bond with enamel

Question 14

What are the features of cavities for composites?

Answer 14

Outline dictated by spread at ADJ
no minimum depth of cavity
retention provided largely by adhesion

Question 15

What are the pros and cons of tunnel prep?

Answer 15

Very conservative

very difficult access makes clearing caries at ADJ diffcult

Time consuming

Question 16

Why is unsupported enamel less of a concern with composites?

Answer 16

Support with GIC base can be done

it bonds with composite anyway

Question 17

Which instruments give no tactile feedback?

Answer 17

Air abrasion and laser

Question 18

What does sealing the dentine from the oral environment encourage in a cavity?

Answer 18

Arresting of the lesion progression

Question 19

How would you be minimally invasive when restoring a cavity?

Answer 19

• Ensure true cause of caries is addressed
• Selective caries removal
• Do not expose the pulp
• Sound margin at ADJ with enamel
• Use magnification
• Minimise iatrogenic damage