Cavity Preps Flashcards
In what cases do we need to end with diverging walls in class I?
When needing to remove enamel undercuts (unsupported enamel)
Where should the pulpal floor be?
Always on Dentin, ideally just below the DEJ
Pulpal floor is flat or follows the rise and fall of occlusal surface
What is the ideal orientation of enamel rods in a prep?
full length of rods, supported by shorter rods both attached to sound dentin
In what cases should we reduce the cusp tips?
when caries covers 1/2 distance from primary groove to cusp tip
when caries covers 2/3 from an adjacent primary groove to the cusp tip
What is a dovetail?
= a primary retention feature (extension for retention)
What is the guideline for formation of the proximal box in class II?
extend gingivally past either caries or occlussal contact (whichever is deeper)
2/3 expense of enamel, 1/3 expense dentin
What form does the axial wall of the proximal box has?
faciolingual contour of proximal tooth surface
In which cases are cusp reductions usually required in class II?
DB cusp of maxillary M2
D cusp of mandibular M1
When is Adjoining restorations permissible?
when the remaining has adequate resistance and retention forms
What do we need to consider for class II on mandibular P1?
- location of pulp chamber
- size of lingual cusp
- entry of bur should be tilted at bisector of angle between long axis of tooth and line perpendicular to faciolingual cusp tips
Where are retention grooves placed in the class II proximal box?
axiolingual and axiofacial line angles always in bisector
Where are retention grooves placed in the lingual prep of 2 surface class I?
distoxaial and mesioaxial line angles
The depth of retention grooves is usually the size of half the diameter of the bur used (0.25 - 0.5 mm deep)
What secondary retention features do we place for class V?
Retention grooves: occlusoaxial and gingivoaxial
Retention coves:
in each axial point angle
If the facial wall is divergent what secondary retention feature is added?
A retention undercut in the faciopulpal line angle
Which area do carries grow faster in?
Pit and fissure
When you need to prepare retention grooves,
these should be:
a. On the DEJ.
b. 0.2 mm inside dentin.
c. 0.5 mm inside dentin.
d. On the deepest part of the preparation.
c. 0.5 mm inside dentin
Which of the following tooth preparations
require more often secondary retention form?
a. Class I.
b. Two surface Class I.
c. Class II.
d. Class V.
d. Class V
Complex amalgam indications:
- Cusp fracture, severe caries lesion, replacement of old restoration
- When 1 or more cusps need to be covered
- When additional retention and R forms needed
- Definitive restorations
- As interim (temporary) restorations
- In teeth with questionable endodontic or periodontal prognosis
- Foundations and core build ups
Complex amalgam contraindications:
- When a proper anatomic and functional form cannot be achieved with a direct restorative material
- When the tooth is aesthetically important
What are the 3 types of pins?
- Cemented pins
- Friction-locked
- Self-threading pins
What are the precautions if pulpal perforation occurs with wrong pinhole placement?
- place Ca(OH)2
- prepare another pinhole 1.5 mm away
- endo therapy
What are the precautions if perforation of external tooth surface occurs with wrong pinhole placement?
- careful probing
- radiographic examination
- occlusal or apical to gingival attachment
Perforation occlusal to gingival attachment treatment options:
- cut the pin (no further treatment)
- remove the pin, enlarge pinhole, restore w/ AMG
- indirect restoration
Perforation apical to gingival attachment treatment options:
- osteoctomy, enlarge pinhole, restore w/ AMG
- crown lengthening, place margin of a cast restoration to gingival perforation
When conventional retention features are not
available, what other additional features may be needed?
- pins
- slots
When would you bevel/not bevel the facial surface of anterior teeth?
not bevel if there is unsupported enamel
When would you bevel/not bevel the lingual surface of anterior teeth?
bevel if large restoration
not bevel if it is a small restoration
For complex AMG what should be also used
in the remaining vertical walls?
Coves and retention grooves
What is a slot?
= is a horizontal retention groove in dentin, placed in the gingival floor of a preparation
-When there is no vertical walls, slots may be needed for
retention
When do we use pins?
whenever adequate resistance and
retention forms are not able to be established with
grooves, slots or coves
What are the cautions indicated when using pins?
– Craze lines or fractures may be created
– Internal stresses in dentin are developed
What are the steps for AMG application?
- prep
- trituration
- condensation
- precarve burnishing
- carving
- adjust occlusion
- postcarve burnishing
- finishing and polishing
Where can we place secondary retention grooves?
class III, class V and complex amalgam restorations
How is the rotary instruments alignment for facial or lingual caries?
Perpendicular to the external surface of the tooth
What is an Outline form?
=the overall outline of the preparation
What happens if you hit an adjacent tooth while doing the prep on another tooth?
- if tiny fragment you can polish it
- if big then do another restoration
What are the advantages of lingual approach?
- The facial enamel is conserved for enhanced esthetics -Shade matching of the composite is less critical
- Discoloration or deterioration of the restoration is less visible
