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Core build up and Amalgam bonding

Core build up and Amalgam bonding. 12 th October. Learning outcomes. 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

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Core build up and Amalgam bonding

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  1. Core build up and Amalgam bonding 12th October

  2. Learning outcomes • 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

  3. Core Definition • 'that part of a preparation for an indirect restoration consisting of restorative material'.

  4. Types of Core Materials • Amalgam • Composite • Glass Ionomer • Resin Reinforced Glass Ionomer • Compomer

  5. AMALGAM Advantages • Not especially technique sensitive • Strong in bulk section • Sealed by corrosion products

  6. Disadvantages • 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

  7. How is the amalgam retained as the core?

  8. Retention Form • Resistance Form

  9. How is the amalgam retained as the core? • Mechanical • Retentive grooves and notches • Pin Placement • Adhesion

  10. Amalgam Bonding A technique to bond amalgam to the cavity.

  11. Aims Behind ‘Bonded Amalgams’ • 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

  12. Materials for Amalgam Bonding • Resin Cements ( Panavia) • Adhesive Bonding Agents -initially designed for composites -OptiBond solo -Amalgambond -Scotchbond multipurpose

  13. OptiBond solo

  14. How do they work? • 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 4-META adhesive

  15. Claimed Advantages of Amalgam Bonding Techniques • Decreased microleakage • YES • Increased amalgam retention • YES, if cavity lacks mechanical retention • Avoids risk of using pins • YES, 20% of pins perforate, 80oC rise

  16. Claimed Advantages of Amalgam Bonding Techniques • Improved amalgam margins • Depends on adhesive used. Panavia weakens amalgam at margins • Technique may reduce incidence of ditching • Tooth reinforcement • YES, if large cavity • NO, if small cavity

  17. Clinical Indications • 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

  18. Bonding Agents • 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

  19. Limitations of Technique • Increased cost of restoration • Technique sensitive? • Not in use long enough to permit adequate evaluation of clinical performance • Adhesion may breakdown over time

  20. 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

  21. References • 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.FThe 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

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