Core Restorations Flashcards
what is another name for core restorations
foundations
what are core restorations for
to replace missing tooth structure prior to crown preparation
when is a core necessary
- no preparation should be extended farther into the tooth than 1.5mm at the cervical line or down 1.5mm from the central fossa
- no wall of dentin should be reduced to a thickness less than its height for sake of retnetion
- if 50% or more of the coronal tooth structure remains sufficient retention for a single crown can be achieved by adding retentive features to the preparation
what are the materials used for core restorations
- dental amalgam alloy
- composite resin
- glas ionomer/resionomer
what are the advantages to amalgam alloys
- easy to manipulate
- favorable mechanical properties ( high compressive strength, wear resistance, and dimensional stability)
- corrosion products
- acceptable for areas difficult to isolate
- relatively inexpensive
what are the limitations to amalgam alloys
- relatively slow setting- cannot be prepared at the same appointment, high copper spherical amalgam alloys (set 15 min)
- corrosion: may cause discoloration of tooth structure
- do not adhere to tooth structure
- require a certain thickness for strength
- color
what are the limitations of composite resin core
- bond strength to dentin is weak, require mechanical retention
- very susceptible to moisture contamination
- requires good isolation the core margins must be supragingival (2mm tooth structure to provide a ferrule)
- polymerization shrink
what are the advantages of composite resin core
- bond to tooth structure although the bond strength to dentin is weak
- can be used in thickness less than 1mm
- rapid polymerization - can be prepared the same visit
- time efficient, economical
- relatively easy to manipulate
what are the types of composite resin core
- light polymerized composite resins (hybrids)
- chemically polymerized (para core)
- dual polymerized (light activated and chemically polymerized) - fluorocore
what are the glass ionomer cements and resin ionomers
- glass ionomer cements- also available metal reinforced glass ionomers
- resionomers/hybrid ionomers- hybrid of traditional glass ionomer cements and composite resin
what are the disadvantages of glass ionomer cements and resin ionomers
- significantly inferior strength compared to amalgam alloys or composite resins
- water imbibition
when are glass ionomer cements and resin ionomers recommended
only for low stress bearing areas or as block out materials for undercuts
how is retention of core build ups achieved most times
with the use of pins whether an amalgam alloy or resin core is used
what are the types of threaded pins
- minikin (0.017 inch)
- minim (0.021 inch)
where should the pins be placed
one pin per missing cusp/marginal ridge
- 4 maximum
