A SHORT REVIEW OF AMALGAM RESTORATION FROM RESTORATIVE DENTISTRY

1. OVERVIEW OF
AMALGAM RESTORATION
DR. SARANG SURESH HOTCHANDANI

2. CONTENTS
• INTRODUCTION
• GENERAL TOOTH PREPARATION
• TYPES OF AMALGAM
• HISTORY
• GENERAL CONSIDERATIONS
• GENERAL CLINICAL TECHNIQUE
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3. INTRODUCTION
•It is a Direct Metallic Restorative
material.
•Amalgam means alloy of mercury with
another metal.
•Mixture of silver-tin-copper alloy and
mercury.
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4. GENERAL TOOTH PREPARATION FOR AMALGAM
• Possess a uniform specified minimum specified thickness
for compressive strength (1.5-2 mm)
• Produce a 90-degree amalgam angle at the cavo-surface
margin (butt joint form)
• Be mechanically retained to tooth (undercut formation)
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5. TYPES OF AMALGAM
• Conventional amalgam restoration
• Desensitizer is used (5% glutaraldehyde + 35% hydroxyl-ethyl methacrylate [HEMA])
• Bonded amalgam restoration
• Bonding, technique & isolation similar to composite
• Retention is minimal
• Strengthen the remaining tooth structure
• However, tooth preparation is similar to conventional amalgam restoration defined above.
• Sealed amalgam restoration
• In this light cured adhesive is placed under amalgam restoration to close dentine.
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6. HISTORY OF AMALGAM
Initially, dentists use silver coins in
filling and mixing these filling with
mercury, creating a putty like mass that
was placed into defective tooth.
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7. CURRENT STATUS OF AMALGAM
• Today popularity is decreased because of;
• Reduction in caries rate
• Esthetic concerns
• Development of composites (primary cause of
reduction in use of amalgam)
• Environmental concerns
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8. TYPES OF AMALGAM 8

9. LOW COPPER AMALGAM
•Prominent till 1960.
•Composition
•Silver; 65% wt.
•Tin; 29% wt.
•Copper; <6% wt.
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10. LOW COPPER AMALGAM
•This type of amalgam results gamma-two phase
(tin-mercury) which showed corrosion.
• This corrosion led to breakdown of amalgam.
• That’s why High copper amalgam were developed to
eliminate this corrosion created by gamma-two phase.
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11. HIGH COPPER AMALGAM
• Currently used today
• Reduces formation of gamma-two phase (reacts with tin) resulting decreased
corrosion but;
• Corrosion still occurs which is beneficial because it provides marginal sealing of amalgam
to cavity walls.
• Composition
• Silver; 40% wt.
• Copper; 12% - 30% wt.
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12. HIGH COPPER AMALGAM
• This material can provide performance for more than 12
years
• Two types of high copper amalgam
• Spherical amalgam
• Admixed amalgam
• Zinc containing high copper amalgam does not show
delayed expansion on condensation.
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13. EFFECT OF “ZINC” IN AMALGAM
•Enhance mechanical properties
•Reduce marginal fracture
•Prolong the service of restoration
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14. TRITURATION
• it is the process by which amalgam alloy powder is mixed with
liquid mercury.
• The powder may be;
• Lathe cut ( milling(crushing) an ingot(slab) of the alloy)
• Spherical type (atomizing liquid alloy)
• Admixed
• Contain both lathe cut and spherical type of alloys.
• Filing; when dental amalgam alloys contain only lathe cut particles.
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15. SPHERICAL AMALGAM
•Little condensation pressure.
•High early strength.
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16. ADMIXED AMALGAM
•More condensation pressure (required
by many dentists)
•Displaces matrix bands to generate
proximal contacts more easily.
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17. NEW AMALGAM ALLOYS
•Mercury free
•Lowe mercury amalgam
•Alloys with gallium or indium or gold alloys
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18. POINTS TO CONSIDER…
• It has been theorized that during mastication, pressure of 200 MPa and this
force with friction can generate heat which would break bond in amalgam and
release mercury in the oral cavity.
• 12 amalgam restoration would release 1.7 micro gram per day.
• Dental amalgam restoration contains approx. 50% mercury.
• Hypersensitivity to mercury is extremely rare.
• Less than 1% showed clinical features of hypersensitivity to mercury (oral lichenoid
reaction, erythematous, burning or itching)
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19. IMPORTANT PROPERTIES OF AMALGAM
• Linear coefficient of thermal expansion of amalgam is 2.5
times greater than tooth structures.
• While it is close to composite.
• Linear coefficient of thermal expansion; the change in size per
degree change in temperature.
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20. IMPORTANT PROPERTIES OF AMALGAM
•Compressive strength is similar to tooth structure.
•Tensile strength less than tooth structure.
• Make amalgam prone to fracture
•Usually amalgam fracture is bulk fracture not
marginal fracture.
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21. IMPORTANT PROPERTIES OF AMALGAM
•Amalgam is brittle and have low edge
strength
•Amalgam should have sufficient bulk (1.5-
2 mm) and 90 degree or greater marginal
configuration.
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22. IMPORTANT PROPERTIES OF AMALGAM
•No clinically relevant creep or flow is shown
by amalgam.
•Creep/flow; it is the deformation of material
under load.
•Amalgam is good thermal conductor
•Always use base/liner under this material.
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23. GENERAL CONSIDERATIONS OF AMALGAM 23

24. INDICATIONS & USES
• Class 1, 2 & 5 cavities, root caries or areas where isolation is not
possible.
• Coz, amalgam has greater wear resistance than composite and
• There is no any effect of contamination on amalgam restoration
• Temporary caries control restorations till final restoration is
placed.
• Foundations (core buildup for crown)
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25. CONTRAINDICATIONS TO AMALGAM
• Allergy to alloys
• Esthetic areas
• Weakened tooth structure which can be
preserved by composite do not use amalgam.
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26. ADVANTAGES V/S DISADVANTAGES
ADVANTAGES OF AMALGAM RESTORATION DISADVANTAGES OF AMALGAM RESTORATION
 Ease of use/ least time consuming
 High compressive strength/strong
 Excellent wear resistance (similar to tooth)
 Long term durability
 Low cost than composite
 Reduced micro-leakage due to formation of
corrosion products at the tooth-amalgam
restoration
 No alteration of gingival flora as compared to
composite when placed in root caries
Cusp fracture is not caused by amalgam restoration
but it is caused large cavity preparation used form
amalgam.
 Non-tooth colored/non-esthetic
 Mechanical bonding to tooth
 Large natural tooth removal
 Difficult tooth preparation
 Initial marginal leakage
 Limited edge strength
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27. GENERAL CLINICAL TECHNIQUE 27

28. INITIAL CLINICAL
PROCEDURES/CONSIDERATIONS
•Complete examination, diagnosis and
treatment plan before start of
restoration.
•Assessment of occlusion.
• Identify contacts on tooth to be restored and
opposing and adjacent teeth
• Help in planning outline form and occlusal
contacts on restoration.
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29. INITIAL CLINICAL
PROCEDURES/CONSIDERATIONS
• Local anesthesia
• Placement of wedge in gingival embrasure.
• Separate the operated tooth
• Protect rubber dam & interdental papilla
• Isolation of operating site with rubber dam or cotton rolls.
• Visualize anticipated extension of the tooth preparation
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30. TOOTH PREPARATION OF
AMALGAM RESTORATION 30

31. REQUIREMENTS
• Amalgam margin 90 degree or greater (butt-joint
form) coz of amalgam’s low edge strength.
• Adequate depth of 1.5 – 2mm thickness for
adequate compressive strength.
• Adequate mechanical retention form (undercut
form)
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32. INITIAL TOOTH PREPARATION DEPTH
• Initial pulpal depth in cavity for amalgam filling should be;
• One half length of the No. 245 bur (1.5mm) (total length of this bur is; 3mm) OR
• 1.5 mm measured from central groove OR
• 0.2 mm inside/ internal to DEJ
• Depth for axial wall should be;
• 0.2 mm inside DEJ if retention grooves are not going to formed
• 0.5 mm inside DEJ if retention grooves are going to formed
• Axial depth on root surface
• 0.75 – 1 mm deep
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33. 33

34. 34

35. OUTLINE FORM
• The extension of cavity depends primarily on amount of caries, old restorative
material or defect.
• Preserve the strength of cusps and marginal ridges.
• Try to extend cavity around the cusps and avoid undermining of dentinal support of marginal
ridges.
• Extend facial and lingual proximal walls into facial or lingual embrasure but not
beyond it
• The less the outline form the more conservative is the cavity and less the tooth
structure is removed.
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36. CAVOSURFACE MARGIN
• Must be 90 degrees or greater. Butt joint should be formed
between amalgam & tooth structure.
• Occlusal margins should be made in such a manner that full length
of enamel rods or buttressed by shorter enamel rods
• Central groove after carving should be rounded
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37. 37

38. PRIMARY RETENTION FORM
• Mechanical locking of amalgam into surface irregularities
of cavity
• Vertical walls especially facial/lingual should converge
occlusally.
• These both primary retention features can be obtained
by “pear shaped carbide bur No. 330 or 245)
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39. PRIMARY RESISTANCE FORM
• Resistance features which prevent THE TOOTH from
fracturing are obtained by;
• Maintaining as much unprepared tooth structure as possible
(preserving cusps & marginal ridges)
• Making pulpal & gingival walls perpendicular to occlusal forces
• Having rounded line angles
• Removing unsupported or weakened tooth structure.
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40. PRIMARY RESISTANCE FORM
• Resistance features which prevent THE AMALGAM from fracturing
are obtained by;
• Adequate thickness of amalgam
• 1.5 – 2 mm occlusal cavity
• 0.75 mm in axial areas
• Margins of amalgam greater or equal to 90 degrees.
• Box like cavity form which provide uniform amalgam thickness.
• Rounded line angles.
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41. CONVENIENCE FORM
Obtained by extending outline
form, walls or margins.
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42. SECONDARY RESISTANCE FORM
Obtained by pins, grooves, coves,
slots, steps, amalgam pins.
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43. RESTORATIVE TECHNIQUES 43

44. Tooth
Preparation
Application of
Desensitizer
Matrix in case
of Proximal
Restoration
Insert Mixed
Amalgam into
Cavity
Carving of
Amalgam
Finishing
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45. 45

46. Matrix Placement in case of Proximal
Restoration
• Provide proper contact & contour
• Confine restorative material
• Reduce amount of excess material
• It should be easily applied and removed, extend below gingival margin, extend above
marginal ridge height & resist deformation during insertion of restorative material.
• Matrix can be applied during tooth preparation.
• In this case matrix is applied on that tooth which is adjacent to tooth which is being prepared.
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47. Filling or Condensation of Amalgam
• Spherical is easily condensed than admixed.
• Smaller amalgam condensers are used first to
allow amalgam to be condensed in the grooves,
coves, line angles etc.
• Burnish the amalgam with burnisher to finalize
condensation.
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48. Carving of Amalgam
• Occlusal areas;
• A discoid-cleoid instrument is used for this purpose.
• The rounded end (discoid end) of discoid-cleoid instrument is positioned on the
unprepared enamel adjacent to the amalgam margin and pulled parallel to margin.
• The pointed end (cleoid end) is used for creating primary grooves, pits or cuspal inclines.
Or these can also be made with Hollenbeck carver.
• Mesial & distal pits should be inferior to marginal ridge height to prevent wedging of food
into occlusal embrasure.
• For large class 2 or foundation restorations, the initial carving of the occlusal surface
should be rapid, concentrating primarily on the marginal ridge height and occlusal
embrasure areas.
• These areas are developed with explorer or carving instrument by mimicking adjacent tooth.
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49. Carving of Amalgam
•Facial and Lingual areas;
• Hollenbeck carver/ amalgam knife is useful in carving
these areas.
•Proximal Embrasure Areas;
• Made by amalgam knife
• Assessed by visual examination & dental floss.
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50. THE END
DR. SARANG SURESH HOTCHANDANI
(BDS)
hotchandaniss@hotmail.com
Larkana, Sindh, Pakistan
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