Direct Restorative Procedures Flashcards
Possess uniform specified minimum thickness for strength
Resistance form
For maximum edge thickness at margin for amalgam
90 degree amalgam butt joint angle
How does amalgam self seal
By corrosion products in the meantime needs varnish to protect pulp
Polishing of amalgam is done
After 24 hours
For which tooth pulpal and gingival floors prepared parallel to occlusal surface
Mandibular 1st premolar
Internal angle of amalgam should be
Rounded
How much is adequate thickness of amalgam
1.5-2.0 mm in areas of occlusal contact
0.5 mm in axial areas
A beveled cavosurface margin will lead to
Fracture of thin amalgam
Occlusal of posteriors, occlusal thirds of facial and lingual of molars, palatal of max molars
Class I
Ideal cavity dimensions for class I amalgam
Depth: 1.5-2 mm
Width: 1.0-1.5 mm
Width of marginal ridges should be atleast how much for class I restoration
1.5 mm in premolars
2mm in molars
Mesial and distal cavity walls are prepared with slight occlusal divergence to
Ensure that proximal marginal ridges are not undermined
Dentinal depth of axial walls in class II preparation
If in enamel 0.5-0.6 mm in dentin
If in cementum 0.7-0.8 mm in dentin
Minimal proximal extension
0.5mm
Proximal contact areas in posterior teeth are located
More buccally
In class II amalgam preparation 90 degrees cavosurface margin achieved by
Reverse curve on buccal
Primary retention form in class II cavity preparation achieved to prevent restoration getting dislodged proximally is by
Dovetail
All external walls are prepared perpendicular to the external tooth surface in
Class V amalgam preparation
Retention achieved in class V amalgam restoration by
Two retention grooves
One of gingivoaxial and one on occlusoaxial
What are the 3 types of retentive pins
Cemented, self threading, friction locked
What is the most common type of retentive pin
Self threading
Retentive pin holes depth and diameter
Depth: 1.3-2 mm ideally 2 mm
Diameter
0.04-0.1 mm smaller than diameter of pin
What permits the insertion of threaded pin into a hole of smaller diameter
Elasticity of dentin
Occlusal clearance for retentive pin
Should be sufficient to provide 2 mm of amalgam over the pin
What is done to reduce polymerization shrinkage in composite
2mm increment curing
Retention in composite is obtained by
Micromechanical retention by bonding
Composite bonds more reliably to
Enamel
To reduce polymerization shrinkage of composite in proximal boxes
Oblique increments
Darker shades of composite
Dark or opaque require increased curing time
For class III which approach is preferable
Lingual approach
Where can you leave unsupported enamel?
In non occlusal stress areas like class III
Extra retention can be achieved in class III by
Grooves or adding bevel
Bevel in class III composite can be
At 45 degrees
For esthetic purposes
For class IV composite restoration retention by
Retention groove
Enamel bevel to increased in width
Width of the bevel for composite restoration
0.5-2mm
When do you not use composite for class V preparation
Defects involving root surface for chemical adherence
Decreased salivary function or lack of pt motivation for fluoride release
Enamel bevels for class V
Placed on occlusal margin but not on gingival margin
Acid etching of enamel
-Increases surface area
-Increases surface free energy
-37% phosphoric acid for 15 secs
How does bonding work on enamel
Creates resin microtags in enamel for adhesion
Organic and inorganic debris resulting from tooth preparation
Smear layer
Removes smear layer and demineralizes calcified tissue
Acid etchant
What happens to dentinal tubules after etching
Fluid in dentinal tubules exit out on enamel which is hydrophilic and bond is hydrophobic so primer helps with this
What does etching do to dentinal surface
Recuces surface energy so primer will increase surface energy
When primer and bonding agents applied to etched dentin they penetrate
Intertubular dentin to create hybrid layer
Open dentinal tubules forming resin tags
Dentin close to pulp has less predictable bonding because
Wider dentinal tubules so less hybrid layer formation
