CHAPTER 13-14: INTRODUCTION TO AMALGAM RESTORATION / CLASS I-II, VI

AMALGAM

• Metallic restorative material: alloy of silver–tin–copper + mercury

• Placed into a prepared cavity and hardens to restore tooth form & function

• Silver-colored filling, in use for 150+ years

• Cost-effective and widely researched material

Unique feature: self-seals margins by corrosion products → reduces microleakage

In addition, amalgam is the only restorative material with an interfacial seal that improves over time.

History of Amalgam

• Introduced in U.S. in 1830s

• First made from silver coin filings + mercury

• Improvements followed with research → better formulations

• 1990s: debates over mercury toxicity

• Once primary restorative material for >150 years

• Decline in popularity today due to:

  • Esthetic demand for composites

  • Less invasive tooth prep with composites

  • Decreased caries prevalence

• Still widely used for strength & cost-effectiveness

safe concerns of amalgam

• Concerns: Mercury toxicity

• Studies & agencies (ADA, USPHS, WHO, FDA) show:

  • Amalgam is safe & effective

  • No causal link to systemic diseases

• Main risk: improper handling during placement/removal

• Mercury disposal = ecological risk

• Regulations in countries (Japan, Sweden, Germany, Canada) restrict or phase out amalgam

• ADA recommends best management practices for amalgam waste

TYPES of amalgam restorations

low-copper amalgam

high-copper amalgam

low-copper amalgam

• Used before 1960s

• Setting reaction forms Gamma-2 (Sn–Hg) phase

• Prone to corrosion - rapid breakdown of restorations

• Consists of irregular-shaped particles

• Requires more condensation pressure

• Heavier condensation helps displace matrix bands - easier proximal contacts

• Tin reacts with Mercury

• Forms Gamma-2 (Sn–Hg) phase

• Gamma-2 = weak & highly corrosive

• Corrosion = restoration breakdown

high-copper amalgam

• Used predominantly today

• Contains ≥12% copper

• Copper reacts with tin - eliminates weak Gamma-2 phase

• Stronger & more corrosion-resistant than low-copper

• Small corrosion at margins helps seal restoration

• Long-lasting 12+ years of service

• Available as spherical or admixed types

• Tin reacts with Copper

• Gamma-2 greatly reduced

• Less Gamma-2 = less corrosion

• Reduced corrosion =

  longer durability (12+ years)

Types of High-Copper Amalgam Alloys

spherical amalgam

admixed amalgam

spherical amalgam

• round alloy particles

• needs little condensation pressure

• high early strength

• suited for large restorations, complex amalgams

admixed amalgam

• Irregular (sometimes mixed with spherical)

• Needs more condensation pressure

• Pressure helps form better proximal contacts

• Preferred when dentists want tighter contacts with adjacent teeth

NEW amalgam alloys

• Developed due to concerns about mercury toxicity

• Include:

Gallium alloys : Mercury-free, but unstable & corrode easily

Indium alloys : Low-mercury, better mixing, but not durable enough

Cold-welding techniques : Mercury-free, uses pressure bonding, but too weak

• Aim: Mercury-free or low-mercury alternatives

• Limitation: None are reliable enough for universal clinical use

PROPERTIES OF AMALAGAM

very high compressive strength (good under biting force) — strong in posterior teeth

low tensile strength (brittle under stretch) — needs bulk to resist fracture

moderate-low diametral tensile — explains splitting tendency

poor flexural strength — needs proper cavity support

low fracture toughness (prone to crack) — avoid sharp cavity angles

COMPRESSIVE STRENGTH

• . Amalgam is strongest in compression and weaker in tension and shear

• The prepared cavity design and manipulation should allow for the restoration to receive compression forces and minimum tension and shear forces.

• The compressive strength of a satisfactory amalgam restoration should be atleast 310 MPa.

TENSILE STRENGTH

• Amalgam is much weaker in tension

• Tensile strengths of amalgam are only a fraction of their compressive strengths

• Cavity design should be constructed to reduce tensile stresses resulting from biting forces

• High early tensile strengths are important - resist fracture by prematurely applied biting forces

DIAMETRAL TENSILE STRENGTH

• Alternative test for brittle materials like amalgam.

• Measures resistance to splitting forces.

• Amalgam shows moderately low values, reinforcing its brittle nature.

• Clinical relevance: explains why thin amalgam restorations fracture easily.

FLEXURAL STRENGTH

• Amalgam has poor flexural strength.

• Cannot resist bending forces well.

• Clinical relevance: cavity design must provide strong support to restoration

FRACTURE STRENGTH

• Low fracture toughness compared to tooth structure or ceramics.

• Brittle material → cracks can propagate under stress.

• Clinical relevance: sharp internal line angles in cavity prep should be avoided to reduce stress concentration.

EXPANSION/DIMENSIONAL CHANGE

change in volume (expansion or contraction) during/after setting.

Clinical Note: Proper condensation reduces residual mercury → minimizes dimensional changes.

Conventional amalgam:

• Zinc-containing types → may undergo delayed expansion when contaminated with moisture.

• Can cause protrusion of restoration & marginal gaps.

High-copper amalgam:

• More dimensionally stable (less expansion/contraction).

• Improved marginal seal compared to older formulations.

Conventional low copper amalgam

have high creep values and exhibit poor marginal integrity over time as the amalgam creeps into a thin layer and then breaks of creating marginal ditching.

Contemporary high copper amalgams

have low creep values and maintain good marginal integrity as a Function of time.

CREEP

deFined as time dependent plastic deformation of a material under static load or constant stress. his property is important with silver amalgam.

Significance: Creep is one of the few properties that directly predicts clinical longevity of amalgam restorations.

THERMAL CONDUCTIVITY

is the rate at which thermal changes are conducted through a material.

• Amalgam = good conductor of heat and cold (like metals).

• Effect in mouth:

  • Rapid transmission of temperature changes to the pulp.

  • May cause postoperative sensitivity if remaining dentin is thin.

• Clinical solution:

  • Use liners or bases (CaOH, GIC, or zinc phosphate cement) if dentin <2 mm to protect pulp.

• Comparison:

  • Amalgam = conductor

  • Composite = insulator (but has higher sensitivity due to other reasons → polymerization shrinkage, microleakage).

ADVANTAGES of amalgam

• Ease of use, Easy to manipulate

• Relatively inexpensive

• Excellent wear resistance

• Restoration is completed within one sitting without requiring much chair side time.

• Well condensed and triturated amalgam has good compressive strength.

• Sealing ability improves with age by formation of corrosion products at tooth amalgam interface.

• Relatively not technique sensitive.

• Bonded amalgams have "bonding benefits".

• Less microleakage

• Slightly increased strength of remaining tooth structure.

• Minimal postoperative sensitivity.

disADVANTAGES of amalgam

• Unnatural appearance (non esthetic)

• Tarnish and corrosion

• Metallic taste and galvanic shock

• Discoloration of tooth structure

• Lack of chemical or mechanical adhesion to the tooth structure.

• Mercury toxicity

• Promotes plaque adhesion

• Delayed expansion

• Weakens tooth structure (unless bonded).

uses of amalgam

Class I, II, V restorations

Foundations

Caries-control restoration

Indications of amalgam

• Moderate to large Class I and II posterior restorations where esthetics are not critical.

• Situations with difficulty in moisture control (saliva, blood, gingival fluids).

• Areas subjected to heavy occlusal stress.

• When cost-effectiveness is a major consideration.

• As foundations (cores) for crowns.

• Temporary restorations in cases needing caries control.

• Extends onto the root surface

• Cannot be well isolated

• tooth that serves as an abutment for a removable partial denture.

contraIndications of amalgam

• Esthetically sensitive areas (anterior region, facial surfaces of premolars/molars visible in smile).

• Small-moderate class I-II & class VI conservative lesions where composite resin provides better esthetics.

• When patient has proven allergy to mercury (rare).

• In cases where strong enamel bonding is advantageous.

• areas that can be well isolated

advantages of using amalgam for Class I, II and VI defects

• Ease of use

• Simplicity of procedure

• Placing and contouring are generally easier than those for composite restorations

disadvantages of using amalgam for Class I, II and VI defects

• Amalgam use requires more complex and larger tooth preparations than composite resin.

• Amalgams may be considered to have a non-esthetic appearance by some patients.

Conservative Class I Amalgam Restorations

done to protect the pulp, preserve tooth strength, and reduce deterioration of the restoration.

By saving as much tooth structure as possible, it minimizes pulpal irritation and keeps the crown strong.

This approach also improves marginal integrity, ensuring a better seal and longer-lasting restoration.

The procedure involves basic steps—preparation, placement, and contouring of amalgam—which can be adapted for more extensive Class I restorations when needed.

Initial Clinical Procedures

After achieving profound anesthesia, isolation of the tooth is recommended—ideally with a rubber dam to maintain field control and ensure mercury hygiene. For a single maxillary tooth with minimal caries, cotton rolls and high-volume evacuation may provide sufficient isolation. A pre-operative evaluation of the occlusal relationship of the treated and adjacent teeth is also essential.

INITIAL TOOTH PREPARATION for CLASS I, II, AND VI AMALGAM RESTORATIONS

establishes the outline form to sound tooth structure with a conservative depth (just inside the DEJ) while providing resistance and retention. For Class I amalgam, only defective pits and fissures are included, avoiding sharp angles.

The resistance principles are:

• Extending around cusps to conserve structure and avoid pulp horns

• Keeping facial and lingual extensions minimal between groove and cusp tips

• Extending to include fissures with margins on sound structure

• Minimally extending into marginal ridges only to remove defects

• Eliminating weak enamel walls if outlines are <0.5 mm apart

• Extending to include enamel undermined by caries

• Using enameloplasty for shallow fissures to conserve structure

• Establishing an optimal, conservative pulpal wall depth

Burs Used for CLASS I, II, AND VI AMALGAM RESTORATIONS

• No. 245 bur (3 mm, 0.8 mm tip) → slight occlusal convergence, rounded line angles for strength

• No. 330 bur → smaller, for highly conservative preps

Entry & Depth for CLASS I, II, AND VI AMALGAM RESTORATIONS

• Punch cut at deepest pit (distal first for visibility)

• Bur parallel to long axis of tooth

• Initial depth: 1.5 mm (reaches DEJ, 0.1–0.2 mm into dentin)

• Final pulpal depth: 1.5–2 mm

• Isthmus width: 1–1.5 mm (just wider than bur) → reduces fracture risk

Outline Form for CLASS I, II, AND VI AMALGAM RESTORATIONS

• Smooth, flowing curves, distinct margins

• Include only defective pits/fissures and undermined enamel

• Minimal extension into marginal ridges (≥1.6 mm premolars, ≥2 mm molars)

• Eliminate weak enamel walls (<0.5 mm apart)

Resistance Form for CLASS I, II, AND VI AMALGAM RESTORATIONS

• Flat pulpal floor in sound dentin

• Minimal external wall extension → preserves tooth strength

• Strong enamel margins supported by dentin

• Depth provides adequate amalgam bulk (resists fracture/wear)

Retention Form for CLASS I, II, AND VI AMALGAM RESTORATIONS

Slight occlusal convergence of walls prevents dislodgment

FINAL TOOTH PREPARATION for CLASS I, II, AND VI AMALGAM RESTORATIONS

• Removal of Defects

  • Eliminate remaining defective enamel and infected dentin on pulpal floor.

  • Small remnants → removed with carbide bur.

  • Larger caries → removed with spoon excavator or slow-speed round bur.

  • Stop excavation once dentin feels hard/firm (not all discolored dentin needs removal).

• Management of Caries Depth

  • Ideal/shallow depth → no liner or base required.

  • Deep areas (≤0.5–1 mm dentin remaining) → place thin RMGI liner (0.5–0.75 mm) only over deepest spot.

  • RMGI functions: pulp protection, fluoride release, bonding, reduces microleakage.

• External Walls & Margins

  • External walls finished earlier.

  • No bevels on occlusal cavosurface.

  • Maintain 90–100° cavosurface angle → 80–90° amalgam angle → strongest margin (“butt joint”).

  • Prevents chipping since amalgam is brittle with low edge strength.

• Cleaning & Inspection

  • Remove debris with air-water spray.

  • Optional: disinfectant.

  • Common method: cotton pellet moistened with water.

  • Apply desensitizer/bonding agent as the first restorative step.

Desensitizer Placement

Applied before amalgam condensation to reduce dentin sensitivity.

• Procedure:

• Apply desensitizer per manufacturer’s instructions.

• Remove excess moisture (avoid over-drying dentin).

• Condense amalgam into place.

• Mechanism: Forms lamellar plugs in dentinal tubules → reduces permeability & sensitivity.

Notes:

• No hybrid layer forms (unlike bonding).

• If amalgam adhesives are used, separate desensitizer usually not needed.

• Concerns remain about durability of adhesives and possible interference with amalgam’s self-sealing ability

MATRIX PLACEMENT

Generally, matrices are unnecessary for a conservative Class I amalgam restoration except as specified in later sections.

Insertion & Carving of Amalgam

Amalgam Selection & Mixing

• High-copper amalgam recommended for better performance.

• Available in pre-proportioned capsules (400–800 mg).

• Some require activation before trituration.

• Mix (triturate) per manufacturer’s instructions.

• Amalgam should be smooth & slightly wet, not dry/crumbly.

• Large restorations may need several mixes.

Insertion & Condensation

• Objectives:

  • Adapt amalgam to cavity walls & matrix.

  • Achieve a void-free restoration.

  • Reduce marginal leakage & corrosion, increase strength.

• Condensation tips:

  • Spherical amalgam → use larger condensers.

  • Admixed amalgam → start with smaller condensers, then larger for over-packing.

  • Condense in increments (1/3–½ depth each).

  • Each stroke should overlap previous one.

  • Over-pack 1 mm beyond cavosurface margin.

  • Condensation must be done within 2.5–3.5 minutes.

CONTOURING AND FINISHING OF THE AMALGAM

Carving

• Begin immediately after condensation with sharp carvers (discoid–cleoid, Hollenback).

• Carve perpendicular to margins; rest blade edge on adjacent unprepared tooth to guide.

• Avoid deep grooves (weakens amalgam).

• Remove flash (thin extension beyond margin).

• Margins must match cavosurface contour.

• Over-carving (>0.2 mm submarginal defect) → replace restoration.

• Carved surface may be smoothed with damp cotton.

Burnishing & Occlusion

Post-carve burnishing:

• Light rubbing → smoother, satin finish.

• Improves marginal integrity & surface smoothness.

Occlusal adjustment:

• Use articulating paper → identify “high” spots.

• Reduce premature contacts until occlusion is stable.

• Contacts should occur on flat surfaces, not inclines.

• Final anatomy must follow normal occlusal contours.

• Advise patient: no heavy biting for 24 hrs.

  Finishing & Polishing

  • Usually not required, but done to:

    • Refine anatomy, contours, margins, texture.

    • Reduce tarnish & corrosion risk.

  • Timing: after 24 hrs (crystallization complete).

  • Finishing:

    • Use white alumina or green carborundum stones → correct margins.

    • Smooth with finishing burs (round or small burs for anatomy).

  • Polishing:

    • Start with coarse rubber points → satiny surface.

    • Progress to medium & fine-grit points → high luster.

    • Keep low speed to avoid overheating (>60°C → pulp damage, mercury release).

    • Alternative: pumice + chalk with rubber cup.

Extensive Class I Amalgam Restorations

Extensive Class I Caries & Amalgam Use

Definition of extensive caries:

• Infected dentin within <1 mm from pulp, or

• Lesion extends up cuspal inclines

Restorative choice:

• Amalgam preferred for large Class I restorations

• Provides excellent wear resistance and maintains occlusal contacts

Bonded amalgam:

• Previously suggested for very large restorations

• No proven advantage over conventional technique when done properly

Initial Tooth Preparation in Extensive Class I Amalgams

Initial Tooth Preparation in Extensive Class I Amalgams

• Liner placement (if needed): Protects pulp before tooth preparation.

• Outline, resistance, retention forms: Established using No. 245 bur.

• Depth: ~1.5 mm at pits/fissures, ~2 mm on external walls (to reach DEJ).

• Extension: Laterally at DEJ to remove undermined enamel.

• Caries on cuspal inclines: Adjust bur axis for 90–100° cavosurface angle (avoids weak margins or over-deep pulpal floor).

• Resistance form: Strong enamel walls, preserved cuspal support.

• Retention form: Achieved by occlusal wall convergence; may include undercuts in dentin.

• Enameloplasty: Used when possible.

• Cusp capping:

  • Indicated if defect > ½ distance between primary groove & cusp tip.

  • Required if defect ≥ ⅔ distance (prevents cusp fracture).

FINAL TOOTH PREPARATION in Extensive Class I Amalgams

Pulp Protection in Extensive Class I Amalgam Preparations

• Remaining infected dentin: Removed as in conservative prep.

• Pulp exposure: Requires direct pulp cap (Ca(OH)₂) or endodontic treatment.

• Very deep caries (<0.5 mm RDT):

  • Place thin calcium hydroxide liner (0.5–0.75 mm) only at deepest area.

  • Stimulates secondary/tertiary dentin formation.

• Cover liner with RMGI base:

  • Provides support against condensation forces.

  • Prevents dissolution, seals excavation.

• Important: Do not cover entire dentin surface—only deepest portion.

• Secondary resistance/retention: Usually unnecessary in extensive Class I.

• Final step: Finish external walls as previously described.

Restorative Technique for Extensive Class I Amalgam

• After liner/base placement: Apply dentin desensitizer

• Amalgam preparation:

  • Triturate as directed

  • Slightly overfill cavity

  • Enhance condensation with precarve burnishing

• Carving:

  • More complex due to cuspal inclines

  • Must establish correct contours, occlusal contacts, grooves, and fossae

• Finishing & polishing: Same techniques as in conservative restorations

Class I Occlusolingual Amalgam Restorations

• Indicated for maxillary molars

• Used when lingual fissure connects with distal oblique fissure and distal pit

• Composite may be an alternative for smaller restorations

Initial Clinical Procedures

• Begin with local anesthesia

• Evaluate occlusal contacts before preparation

• Rubber dam usually recommended for proper isolation

• Cotton rolls may be sufficient for typical Class I preparations

• Found in mandibular molars where fissures extend:

  • From occlusal surface → facial cusp ridge → facial surface

• Preparation & restoration techniques are similar to occlusolingual restorations

• Restorative options:

  • Composite (for smaller defects)

  • Amalgam (illustrated in Fig. 14-38)

• Finishing & polishing:

  • Done after amalgam sets completely

  • Abrasive points may be modified in shape for optimal polishing

Final Procedures: Cleaning and Inspecting

1. Cleaning the preparation

• Flush visible debris with water from syringe.

• Remove visible moisture using a few light bursts of air.

• If debris remains (e.g., clinging to walls/angles):

  • Use an explorer or small cotton pellet to loosen/remove it.

2. Precautions

• Avoid over-drying with air → can dehydrate the tooth and damage odontoblasts in exposed tubules.

3. Inspection

• Ensure the preparation is:

  • Completely debrided (no debris, plaque, or caries).

  • Properly shaped (no unnecessary undercuts or unsupported enamel).

  • No further modifications required before restoration placement.

Purpose of Rigid Matrix

• Prevents “landsliding” of amalgam during condensation

• Ensures marginal adaptation and restoration strength

Tofflemire Matrix Retainer

• Commonly used to secure the matrix band

• Limitation: poor adaptation to the lingual groove → requires reinforcement

Stainless Steel Strip

• Dimensions: 0.002 in thick × 8 mm wide

• Placed between lingual surface & Tofflemire band

• Positioned slightly gingival for added stability

Stabilization Options

• Rigid PVS material between matrices (prevents lingual displacement)

• Green stick compound on wedge → pressed with burnisher for tight seal

Barton Matrix

• Combination of:

  • Tofflemire band

  • Stainless steel strip

  • Rigid support (PVS or compound)

• Provides rigid lingual matrix for proper condensation

• Sometimes sufficient with strip matrix + wedge only

Finishing of the Amalgam Restoration

Carving

• Start immediately once preparation is slightly overfilled

• Instruments: Discoid-cleoid or Hollenback carver

• Carve with blade perpendicular to margin, moving parallel to margin

• Prevent over-carving by guiding along adjacent tooth surface

Matrix & Excess Removal

• Use an explorer to clear excess amalgam near lingual matrix before removal

Final Steps

• Remove rubber dam

• Adjust restoration for proper occlusion

• Finishing & polishing usually not required (only in specific cases)

Purpose of Class II restoration:

• Restore tooth structure lost to caries

• Maintain proper occlusion and contact

• Provide retention and resistance form

Initial Tooth Preparation: Occlusal Outline

Enter pit nearest the carious proximal surface

• Use No. 245 bur with high-speed drill under water spray

• Maintain bur parallel to the long axis of the tooth

Depth and Width of Occlusal Step: Reach DEJ (approximately 1.5–2 mm from occlusal surface)

• Isthmus width narrow, ideally same as No. 245 bur

• Follow the rise and fall of the central fissure

Wall Preparation & Retention Form: Facial, lingual, and distal walls slightly convergent occlusally

• Extend walls to sound DEJ

• Dovetail in distal pit if necessary

• Enameloplasty if indicated

Extension to Proximal Surface: Extend toward the marginal ridge (~0.8 mm short of contact)

• Expose DEJ at marginal ridge

• Width sufficient for proximal box

Class II Amalgam: Proximal Outline Form (Proximal Box)

• Include all caries, defects, or existing restorations

• Create 90-degree cavosurface margins (butt joint)

• Maintain minimal clearance (~0.5 mm) from adjacent teeth

Initial Proximal Ditch Cut: Isolate proximal enamel by cutting a ditch along DEJ

• Cut approximately 2/3 enamel, 1/3 dentin (0.5–0.6 mm enamel, 0.2–0.3 mm dentin)

• Pressure directed gingivally and toward proximal surface

Gingival and Axial Wall Depth: Gingival extension just beyond caries or contact

• Axial wall depth ~0.5 mm; deeper if retention grooves needed

• Premolars may have shallower proximal boxes than molars

Faciolingual and Gingival Divergence: Proximal ditch may diverge gingivally for retention

• Extension includes defective or old material, conserves marginal ridge

• Avoid excessive clearance >0.5 mm unless needed

Completing Proximal Margins: Two cuts from facial and lingual limits perpendicular to proximal surface

• Remaining isolated enamel may fracture; remove with spoon excavator or bur

• Use wedge to protect gingiva and rubber dam

Resistance and Retention Form: Resistance form: pulpal/gingival walls level, preserve cusps, restrict occlusal extension, reverse curve, round internal line angles, sufficient amalgam thickness

• Retention form: occlusal convergence of facial and lingual walls, dovetail if present

Class II Amalgam: Final Tooth Preparation

Removal of Defective Enamel and Infected Dentin: Remove enamel pit-and-fissure remnants

• Remove infected dentin with slow-speed round bur or spoon excavator

• Stop excavation before all stained dentin is removed

Resistance Form Preservation: Maintain pulpal seats perpendicular to tooth axis in sound dentin

• Axial wall caries removal without compromising resistance

• Old restorative material may remain if intact and asymptomatic

• Maintain facial and lingual gingival corners at a more occlusal position

• Careful amalgam placement and light condensation in extended areas

• Gingival Wall Considerations: Maintain facial and lingual gingival corners at a more occlusal position

• Careful amalgam placement and light condensation in extended areas

Minor Variations from Ideal Preparation: Partial facial or lingual wall extension permissible if:

1. Wall is not weakened

2. Extension is accessible and visible

3. Sufficient gingival seats remain

4. Butt-joint fit (90-degree margins) is possible

Secondary Resistance Form

• Retention grooves in axiofacial and axiolingual line angles

• Controversial necessity in narrow conservative proximal boxes

• strengthens tooth

  and restoration

Secondary Retention Form

• Retention grooves in axiofacial and axiolingual line angles

• Controversial necessity in narrow conservative proximal boxes

• Avoid using improperly positioned line angles as guides

Preparation of Proximal Retention Grooves

• Use No. 169 L or No. 14 round bur with air coolant and reduced speed

• Position: 0.2 mm inside DEJ in axiofacial and axiolingual line angles

• Depth: 0.5 mm at gingival floor level, tapering occlusally

Occlusogingival orientation: bur tilt controls occlusal height

- Proximal retention grooves enhance independent retention

• Do not remove dentin supporting proximal enamel

• Do not prepare grooves entirely in axial wall

External Wall Preparation

• Avoid unsupported enamel and irregular margins

• No occlusal cavosurface bevel indicated

• Proximal margin: ideally 90°, maximum 100°

• Amalgam fracture risk if margin angle < 80°

• Occlusal line angle: 90–100° or greater

Gingival Margin Finishing

• Mesial gingival margin trimmer: 6°–20° slight bevel in enamel

• Distal gingival margin trimmer or explorer tine

• No bevel if margin is below CEJ on the root

Purpose of a matrix:

• Restores natural tooth shape

• Maintains contact with adjacent teeth

• Prevents gingival overhang

• Supports filling material during placement

Qualities of a Good Matrix

• Rigid & stable

• Accurate anatomical contour

• Correct proximal contact

• Prevents gingival excess

• Easy to apply & remove

• Universal (Tofflemire)

• – versatile, used for 2–3 surface restorations

• Sectional Matrix

• – contoured, supported by rigid material

• Precontoured Matrix Strips

• – ready-to-use metal strips

CARVING for Class VI Amalgam Restorations

• Use small discoid–cleoid or hollenback carvers for anatomical contour

• Maintain natural cusp/incisal edge morphology

• Carve with occlusal/incisal guidance to restore function

• Avoid overcarving to prevent weak amalgam edges

FINISHING for Class VI Amalgam Restorations

• Delay polishing for 24 hours to allow amalgam to set

• Use finishing burs, stones, or strips (for anterior)

• Smooth cavosurface margins to reduce plaque retention

• Check occlusion carefully (incisal/cusp contacts)

FINISHING for Class VI Amalgam Restorations

• Small defects: repair with fresh amalgam addition

• Older restorations may require retention grooves or slots

• Composite repair possible in esthetic zones

• Indirect restorations for large fractures or wear

1.5 mm

Minimum bulk required for strength and longevity of amalgam

Indications of Class VI Amalgam Restorations

cusp tip/incisal edge breakdown from

attrition, erosion, abrasion, or hypoplastic pits

Common complaints of Class VI Amalgam Restorations

sensitivity, food impaction, sharp

enamel edges, esthetic concerns