Transcript Lecture 09_-_Amalgam_Bonding_131005[1]

Core build up and Amalgam
bonding
12th October
Learning outcomes
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To know the definition of a core build up.
To understand the advantages and
disadvantages of amalgam as a restorative
material
To understand the aims of amalgam bonding
To know the clinical stages to perform a
bonded amalgam
Core Definition
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'that part of a preparation for an
indirect restoration consisting of
restorative material'.
Types of Core Materials
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Amalgam
Composite
Glass Ionomer
Resin Reinforced Glass Ionomer
Compomer
AMALGAM
Advantages
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Not especially technique sensitive
Strong in bulk section
Sealed by corrosion products
Disadvantages
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Best left to set for 24 hours before tooth preparation
Weak in thin section
Mercury content may be of concern to some patients
and dentists
Potential electrolytic action between core and metal
crown
Not intrinsically adhesive
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How is the amalgam retained as the
core?
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Retention Form
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Resistance Form
How is the amalgam retained as
the core?
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Mechanical
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Retentive grooves and notches
Pin Placement
Adhesion
Amalgam Bonding
A technique to bond amalgam to
the cavity.
Aims Behind ‘Bonded
Amalgams’
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Conserve more tooth structure by reducing
the need to remove sound tooth tissue for
mechanical retention.
Increased Amalgam retention.
Reduce marginal leakage
Reduce the need for dentine pins.
Potentially reduce sensitivity
Improve fracture resistance
Improved amalgam margins
Materials for Amalgam
Bonding
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Resin Cements ( Panavia)
Adhesive Bonding Agents
-initially designed for composites
-OptiBond solo
-Amalgambond
-Scotchbond multipurpose
OptiBond solo
How do they work?
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Etching dentine opens up dentinal
tubules enabling adhesive resin to flow
into dentine and is retained
micromechanically
Adhesive resin adheres to amalgam
roughness micromechanically and by 4META adhesive
Claimed Advantages of
Amalgam Bonding Techniques
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Decreased microleakage
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Increased amalgam retention
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YES
YES, if cavity lacks mechanical retention
Avoids risk of using pins
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YES, 20% of pins perforate, 80oC rise
Claimed Advantages of
Amalgam Bonding Techniques
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Improved amalgam margins
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Depends on adhesive used. Panavia
weakens amalgam at margins
Technique may reduce incidence of
ditching
Tooth reinforcement
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YES, if large cavity
NO, if small cavity
Clinical Indications
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Not recommended for routine amalgam
cavities with sufficient mechanical retention
and undercuts. No evidence of increased
benefit to balance increased costs.
Useful for large multisurface amalgams to
avoid use of pins
Useful for amalgam repairs
Some easier to use than others
Bonding Agents
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Technique
Place matrix band ( lightly vaselined)
Etch 10% phosphoric acid
Wash and dry
Apply adhesive ( Kerr Optibond solo)
Blow off excess solvent
Light cure
Pack amalgam
Limitations of Technique
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Increased cost of restoration
Technique sensitive?
Not in use long enough to permit
adequate evaluation of clinical
performance
Adhesion may breakdown over time
Amalgam Bonding
Summary
 Amalgam is an excellent core build-up
material for posterior teeth
 Excellent interim restoration for posterior
teeth
 Adhesives can be used to improve retention
in large amalgam restorations and cores
 Adhesives and preparation features can often
substitute for pin retention for cores
References
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R. W. Wassell, E. R. Smart G. St. George. Crowns and
other extra-coronal restorations: Cores for teeth with
vital pulps. BDJ 2002 May,192(9): 499-509
Setcos J.C, Staninec M, Wilson N.H.F
The development of resin-bonding for amalgam
restorations. BDJ 1999 Apr, Vol186 (7): 328-330
Staninec M, Setcos
Bonded amalgam restorations: current research and
clinical procedure.
Dent Update. 2003 Oct;30(8):430-4, 436