Class I cavity

Question 1

Cavity preparation criteria

Answer 1

Outline form
resistance form
retention form
convenience form
caries removal
smoothing of margins
debridement

Question 2

Outline form

Answer 2

Centered on groove and lesions

depends on posterior tooth, cavity must be centered on groove

Question 3

Minimal distance between opposing margins

Answer 3

isthmus width: 1-1.5 mm
Maximum occlusal width: 1/3 inter-cuspal distance (unless pathology has further extension)

Question 4

Extension for prevention meaning

Answer 4

including groove within cavity design just for prevention

include all the affected enamel and to be finished in sound tooth structure.

width marginal ridge area = 1.5 mm

mesial / distal margins must be located 1/3 - 1/2 the distance between pit and crest of marginal ridge & parallel to it.

Question 5

Retention form

Answer 5

adequate flatness of surface walls and floors to prevent rotation of restoration.

F-L walls slightly convergent towards to occlusal

Occlusal dovetail (lower first molar has exception. Mesial on dovetail, which is parallel to marginal ridge. Fishtail is on distal side)

This is to retain restoration

Question 6

Resistance Form

Answer 6

Resistance to fracture.

Adequate pulpal depth for strength of restoration: 1.5 - 2 mm.

Pulpal floor in dentin, parallel to occlusal table

Proper cavosurface exit angle (90 degree)

Question 7

Minimize Tooth Fracture

Answer 7

Want rounded internal line angles. Sharp ones will fracture tooth itself.

Removal of unsupported enamel

Marginal ridges supported by dentin

*in some cases like upper first molar, margins should extend as little as possible into oblique ridge, distolingual cusp and distal marginal ridge.

Question 8

Convenience Form

Answer 8

Access to determine extent of pathology

access for manipulation of instruments

access for insertion and finishing of restoration

Question 9

Caries removal

Answer 9

all remaining carious dentin removed

dentin should be hard and shiny (may be stained)

placement of liners/bases as needed e.g. Ca(OH)2, GI

Question 10

Procedure

Answer 10

Punch cuts

Make sure pulpal floor is flat, 1.5 mm deep. width of marginal ridge = 1.5 mm

tilt bur a bit to mesial and distal on those sides to make sure all enamel is supported by dentin…

to be continued….