Amalgam Flashcards
Factors contributing to resistance form of amalgam
1- Flat pulpal floor
2- Sufficient depth
3- Minimal extension
4- 90º cavosurface margin
5- Wall parallel to enamel rods
6- Rounded internal preparation angles
Indications of amalgam
Class I, II, V (where esthetic is not important/high caries risk)
Patient desire
Cost
Contraindications of amalgam
Allergy
Esthetic area
Conservative design is better
Factors contributing to retention form:
Primary retention: frictional retention, B-L wall convergence
Secondary retention: dovetail design
Which tooth has a preparation design resembling “snake eyes”?
Mandibular 1st premolars
Which bur can be used for initial amalgam cavity preparation?
245 (330L)/Elongated-pear
330/Pear
In an amalgam cavity preparation, M-D walls should be:
Divergent
The depth of the cavity should be:
1.5-2 mm
Over-triturated amalgam:
Mix is warm, shiny wet and soft
Under-triturated amalgam:
Mix will crumble due to weakness
Properly triturated amalgam:
Good shiny mix; homogenous mass, adhering together
How much should you overfill the amalgam cavity?
About 1 mm
In the postcarve burnishing, the purpose is to:
Improve marginal integrity and smoothness (not shiny)
In postcarve burnishing, which type of burnishers are used?
Small burnishers
Finishing and polishing of amalgam is done at which time?
After 24 hours
In maxillary molars, the outline of distal side of the oblique ridge is:
Round or oval
In maxillary molars, the outline of the mesial side of the oblique ridge is:
Butterfly
When should you extend the cavity preparation across a maxillary molar’s oblique ridge?
When it is undermined by caries
or
Less than 1.0 mm sound ridge structure remaining between M & D preparation
The outline form of maxillary premolars is:
Butterfly or U-shaped
For a mandibular 2nd premolar outline form, when should you not connect the mesial and distal pits?
- Presence of transverse ridge (adds strength)
- Absence of an occlusal fissure
It is permissible to repair a defective portion of an existing amalgam restoration if:
the remaining portion of the original restoration retains adequate resistance and retention form.
When caries are present in the proximal aspect without involving the marginal ridge, a proposed cavity design is:
Slot preparation
Components of a compound class II amalgam cavity:
- Occlusal portion
- Isthmus portion
- Proximal portion
In an amalgam cavity, the isthmus portion should be _______ than the occlusal.
Wider
Lines that are detected for proper freeing of contact; they describe the shape of the buccal
and lingual walls of the proximal cavity at different situations of the contact area.
Ingrham’s lines
In cases of open contact, Ingrham’s lines should be:
Straight
The universal curve is used when:
Wide embrasures and broad contacts
The revers curve is usually done in:
Buccal wall of class II
Advantages of the reverse curve:
- Proper freeing of contact
- Obtaining of 90° C.S.A.
- Increase bulk of the restoration to prevent marginal ditching at the bucco-proximal area
Plunging cusps should be recontoured during:
The initial clinical procedure
In a cavity prep, enter the pit nearest the involved proximal surface with a:
Punch-cut
Which structure is an important guide in the proximal class II preparation?
DEJ
The initial procedure in preparation of the outline form is the isolation of the proximal enamel by doing the:
Proximal ditch cut
The proximal ditch cut is extended:
Gingivally:
- Just beyond the caries
- Or the proximal contact
(whichever is greater)
Ideally, the extension of facial and lingual margins of a proximal box should be equal to _______ to provid:
It should be 0.2-0.3 mm from the adjacent tooth to provide clearance
The axial wall is always placed in the dentin to obtain:
- Resistance & elasticity of dentin
- Bulk of the restoration
- Placement of retentive locks
The axial wall should NEVER be:
Concave
The gingival seat consists of:
2/3rd of dentin and 1/3rd of enamel
To ensure that the faciolingual dimension at the gingival is greater than at the occlusal, the proximal ditch cut may be:
Diverged gingivally
To protect the gingiva and the rubber dam when extending the gingival wall, what could be placed?
A wooden wedge
The proximal retention locks could be placed using which burs?
169L bur or the ¼ bur
Retentive locks are placed in:
Axiofacial and axiolingual line angles
Proximal retention locks should terminate at:
Axiopulpal point angle
Retention locks should be placed _____ inside the DEJ, regardless of the depth of the axial walls and axial line angles.
0.2 mm
The four characteristics or determinants of proximal locks:
1- Position
2- Translation
3- Depth
4- Occlusogingival orientation
What should connect the tooth & amalgam?
Butt joint
The cavosurface bevel should be:
20º
Beveling is not required when:
The gingival margin is gingival to the CEJ
To prevent the microleakege of the amalgam restoration, what should be applied on all the preparation walls?
Varnishes
To reduce the postoperative sensitivity, what could be placed?
GLUMA desensitizer
Disinfection of the preparation walls can be done by:
Silver nitrate
Phenol
Ethyl alchol (short duration)
Amalgam condensation should occur first in:
The proximal box(es), filling about 1 mm first
Early removal of the matrix bands leads to an increased risk of:
Marginal ridge fracture
What may be used to carefully define the occlusal embrasure?
An explorer or a small Hollenback carver
From which direction should the matrix be removed?
Linguooccluasally or (faciooccluasally)
