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Failure in Amalgam Restorations & Their Reasons

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Haritha RK

The take home message from this ppt are the following - - How to identify Failure in amalgam restoration clinically and radiographically while taking an OP - When to replace an amalgam restoration - Case selection for amalgam class I and class II restoration - How to avoid errors in cavity preparation to prevent failure of restoration - Importance of matricing and wedging in class II restorations - Importance of postoperative instructions to the patient

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FAILURE IN AMALGAM RESTORATIONS
The one who falls and gets up is stronger than the one who never tried. Do not fear failure but rather fear not trying - ROY T. BENNETT
CONTENTS Introduction Fracture lines Marginal ditching Proximal overhang Poor anatomic contours Marginal ridge incompatibility Improper proximal contacts Recurrent caries Amalgam blues Voids Bulk fracture of the tooth or amalgam Poor occlusal contacts Signs of failure of amalgam restorations Improper case selection Improper cavity preparation Faulty selection and manipulation of amalgam Errors in matricing procedures and restoration Postoperative factors Reasons for failure of amalgam restorations Conclusion
Introduction Recap session/ Q & A Amalgam restorations can be broadly classified based on?
What are the different phases of amalgam What are the steps in cavity preparation
SIGNS OF AMALGAM FAILURE Sign is an objective evidence of disease perceptible to the examining practitioner
Fracture Line
Marginal Ditching
Proximal Overhang Can be identified clinically and radiologically Confirmed by tearing of dental floss when passed interproximally Failure due to inflammation and destruction of gingival tissues
Poor Anatomic Contours Inadequate embrasure form Flat contours
Marginal Ridge Incompatibility Marginal ridge portion of amalgam restoration should be at same level to adjacent normal tooth If not, poor occlusal embrasure form food impaction and periodontal disease
Improper Proximal Contacts Open contacts Food impaction and periodontal disease
Recurrent Caries
Amalgam Blues Leaching of corrosion products in dentinal tubules or Due to colour of amalgam shown through the remaining thin enamel
Voids Improper condensation risk of secondary caries
Bulk Fracture of Tooth or Amalgam Bulk fracture of tooth sign of lack of resistance Bulk fracture of amalgam sign of lack of retention
Poor Occlusal Contacts Cause improper occlusal functioning and undesirable tooth movement
REASONS FOR FAILURE OF AMALGAM RESTORATIONS
Improper Case Selection INDICATIONS Where esthetics is not a concern Moderate to large cavities Heavy occlusal load Cannot be well isolated Extends onto root surface Foundation for a full coverage restoration Abutment for RPD CONTRAINDICATIONS Esthetically prominent areas in posterior teeth Small to moderate cavities which can be well isolated Inadequate tooth structure to provide resistance and retention forms Malocclusion where opposing occlusal cusp is constantly impinging Bruxism, extensive proximal caries
Improper Cavity Preparation IMPORTANCE OF PRINCIPLES OF CAVITY PREPARATION
Improper Cavity Preparation INADEQUATE EXTENSIONS Preparation error Failure to extend to all defective pits and fissure Inadequate proximal extensions --> Lack of convenience form Reason for failure Improper caries removal OVEREXTENDED CAVITY PREPARATION Preparation error - Prepared cavity greater than 2/3rd the interocclusal distance Reason for failure Amalgam doesnt reinforce the weakened tooth structure
Improper Cavity Preparation SHALLOW CAVITY PREPARATION Preparation error Less than 1.5mm depth Reason for failure Lack of resistance DEEP CAVITY PREPARATION Preparation error Deep cavity preparation Reason for failure Poor pulp protection Prolonged post operative sensitivity and/or pulp exposure
Improper Cavity Preparation CURVED PULPAL FLOOR Preparation error Pulpal floor rather than flat Reason for failure Loss of retention of restoration Create wedging effect chances of fracture NARROW ISTHMUS Preparation error Narrow isthmus Reason for failure Lack of proximal retention form
Improper Cavity Preparation SHARP AXIOPULPAL LINE ANGLE Preparation error Sharp instead of rounded axiopulpal line angles Reason for failure Concentration of stresses Fracture LACK OF BUTT JOINT IN CAVOSURFACE MARGINS Less than 80 Tooth margins fracture due to unsupported enamel More than 110 Feather edge of amalgam Marginal fracture of amalgam
Improper Cavity Preparation LACK OF OCCLUSAL CONVERGENCE Preparation error Divergent facial and lingual walls Reason for failure Dislodged due to lack of retention IMPROPER CONVENIENCE FORM Preparation error Lacks convenience form Reason for failure Improper condensation of amalgam voids lowered strength of amalgam Fracture
Faulty selection and Manipulation of Amalgam Low copper vs High copper alloys Lathe cut low copper alloys to be avoided low strength, high creep undergo tarnish and corrosion High copper alloys preferred Mercury alloy ratio: Ideally between 43-50% Zinc containing vs Zinc free alloys are controversial Zinc containing alloys Delayed expansion Zinc free alloys Less plastic, more brittle, and difficult to handle clinically SELECTION OF ALLOY AND MERCURY
Improper Trituration Improper Condensation Contamination Over and Under Carving Improper Finishing
Errors in Matricing procedures and restoration Poor matrix adaptation is a common cause for failure in Class II and complex amalgam restoration. It may be due to Unstable matrix Poor contour Absence of wedge Premature matrix removal
Postoperative Factors POSTOPERATIVE PAIN AND SENSITIVITY High spots Inflammation of the apical periodontium due to hyper occlusion Check with articulating paper Remove the excess Pain subsides Delayed expansion Zinc containing alloys contaminated with moisture from saliva hydrogen gas is released Internal pressure increased Amalgam expansion 3 to 4 days after restoration is placed Prevent contamination Poor pulpal protection Pulp protecting agents Fracture or cracked tooth syndrome Galvanism Amalgam restorations adjacent or opposing gold restoration Avoid dissimilar metal restoration PREMATURE FRACTURE Occlusal loading immediately after restoration
CONCLUSION Take home message How to identify Failure in amalgam restoration clinically and radiographically while taking an OP When to replace an amalgam restoration Case selection for amalgam class I and class II restoration How to avoid errors in cavity preparation to prevent failure of restoration Importance of matricing and wedging in class II restorations Importance of postoperative instructions to the patient
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Failure in Amalgam Restorations & Their Reasons

  • 1. FAILURE IN AMALGAM RESTORATIONS
  • 2. The one who falls and gets up is stronger than the one who never tried. Do not fear failure but rather fear not trying - ROY T. BENNETT
  • 3. CONTENTS Introduction Fracture lines Marginal ditching Proximal overhang Poor anatomic contours Marginal ridge incompatibility Improper proximal contacts Recurrent caries Amalgam blues Voids Bulk fracture of the tooth or amalgam Poor occlusal contacts Signs of failure of amalgam restorations Improper case selection Improper cavity preparation Faulty selection and manipulation of amalgam Errors in matricing procedures and restoration Postoperative factors Reasons for failure of amalgam restorations Conclusion
  • 4. Introduction Recap session/ Q & A Amalgam restorations can be broadly classified based on?
  • 5. What are the different phases of amalgam What are the steps in cavity preparation
  • 6. SIGNS OF AMALGAM FAILURE Sign is an objective evidence of disease perceptible to the examining practitioner
  • 9. Proximal Overhang Can be identified clinically and radiologically Confirmed by tearing of dental floss when passed interproximally Failure due to inflammation and destruction of gingival tissues
  • 10. Poor Anatomic Contours Inadequate embrasure form Flat contours
  • 11. Marginal Ridge Incompatibility Marginal ridge portion of amalgam restoration should be at same level to adjacent normal tooth If not, poor occlusal embrasure form food impaction and periodontal disease
  • 12. Improper Proximal Contacts Open contacts Food impaction and periodontal disease
  • 14. Amalgam Blues Leaching of corrosion products in dentinal tubules or Due to colour of amalgam shown through the remaining thin enamel
  • 15. Voids Improper condensation risk of secondary caries
  • 16. Bulk Fracture of Tooth or Amalgam Bulk fracture of tooth sign of lack of resistance Bulk fracture of amalgam sign of lack of retention
  • 17. Poor Occlusal Contacts Cause improper occlusal functioning and undesirable tooth movement
  • 18. REASONS FOR FAILURE OF AMALGAM RESTORATIONS
  • 19. Improper Case Selection INDICATIONS Where esthetics is not a concern Moderate to large cavities Heavy occlusal load Cannot be well isolated Extends onto root surface Foundation for a full coverage restoration Abutment for RPD CONTRAINDICATIONS Esthetically prominent areas in posterior teeth Small to moderate cavities which can be well isolated Inadequate tooth structure to provide resistance and retention forms Malocclusion where opposing occlusal cusp is constantly impinging Bruxism, extensive proximal caries
  • 21. Improper Cavity Preparation INADEQUATE EXTENSIONS Preparation error Failure to extend to all defective pits and fissure Inadequate proximal extensions --> Lack of convenience form Reason for failure Improper caries removal OVEREXTENDED CAVITY PREPARATION Preparation error - Prepared cavity greater than 2/3rd the interocclusal distance Reason for failure Amalgam doesnt reinforce the weakened tooth structure
  • 22. Improper Cavity Preparation SHALLOW CAVITY PREPARATION Preparation error Less than 1.5mm depth Reason for failure Lack of resistance DEEP CAVITY PREPARATION Preparation error Deep cavity preparation Reason for failure Poor pulp protection Prolonged post operative sensitivity and/or pulp exposure
  • 23. Improper Cavity Preparation CURVED PULPAL FLOOR Preparation error Pulpal floor rather than flat Reason for failure Loss of retention of restoration Create wedging effect chances of fracture NARROW ISTHMUS Preparation error Narrow isthmus Reason for failure Lack of proximal retention form
  • 24. Improper Cavity Preparation SHARP AXIOPULPAL LINE ANGLE Preparation error Sharp instead of rounded axiopulpal line angles Reason for failure Concentration of stresses Fracture LACK OF BUTT JOINT IN CAVOSURFACE MARGINS Less than 80 Tooth margins fracture due to unsupported enamel More than 110 Feather edge of amalgam Marginal fracture of amalgam
  • 25. Improper Cavity Preparation LACK OF OCCLUSAL CONVERGENCE Preparation error Divergent facial and lingual walls Reason for failure Dislodged due to lack of retention IMPROPER CONVENIENCE FORM Preparation error Lacks convenience form Reason for failure Improper condensation of amalgam voids lowered strength of amalgam Fracture
  • 26. Faulty selection and Manipulation of Amalgam Low copper vs High copper alloys Lathe cut low copper alloys to be avoided low strength, high creep undergo tarnish and corrosion High copper alloys preferred Mercury alloy ratio: Ideally between 43-50% Zinc containing vs Zinc free alloys are controversial Zinc containing alloys Delayed expansion Zinc free alloys Less plastic, more brittle, and difficult to handle clinically SELECTION OF ALLOY AND MERCURY
  • 27. Improper Trituration Improper Condensation Contamination Over and Under Carving Improper Finishing
  • 28. Errors in Matricing procedures and restoration Poor matrix adaptation is a common cause for failure in Class II and complex amalgam restoration. It may be due to Unstable matrix Poor contour Absence of wedge Premature matrix removal
  • 29. Postoperative Factors POSTOPERATIVE PAIN AND SENSITIVITY High spots Inflammation of the apical periodontium due to hyper occlusion Check with articulating paper Remove the excess Pain subsides Delayed expansion Zinc containing alloys contaminated with moisture from saliva hydrogen gas is released Internal pressure increased Amalgam expansion 3 to 4 days after restoration is placed Prevent contamination Poor pulpal protection Pulp protecting agents Fracture or cracked tooth syndrome Galvanism Amalgam restorations adjacent or opposing gold restoration Avoid dissimilar metal restoration PREMATURE FRACTURE Occlusal loading immediately after restoration
  • 30. CONCLUSION Take home message How to identify Failure in amalgam restoration clinically and radiographically while taking an OP When to replace an amalgam restoration Case selection for amalgam class I and class II restoration How to avoid errors in cavity preparation to prevent failure of restoration Importance of matricing and wedging in class II restorations Importance of postoperative instructions to the patient