Amalgam Restorations II

7/30/2019 Amalgam Restorations II

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Amalgam Restorations II

Dr.Ghada Maghaireh

BDS,MS,ABOD


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Lecture Outline

Class II amalgam restorations.

Class V amalgam restorations.

Amalgam mixing & placement.


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Class II Amalgam Preparation

Cavity preparation for

caries that originate in

the proximal surfacesof molars &

premolars.

Usually interproximalcaries starts just

below the contact

point.


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Class II Amalgam Preparation

Occlusal Outline Form

If a groove is not carious,

it should not be included

in the outline.

Faciolingual width is

approximately 1 mm

except at the intersectionof grooves.


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Proximal Outline Form

The cavity should beextended buccally &

lingually to break the

contact with the

adjacent tooth.


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The gingival wall should be

extended gingivally tobreak the contact.

B

L


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Proximal clearnce:0.25-0.5 mm.


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Buccal & lingual wallsshould be parallel.

They can be slightly

convergent towardocclusal.

B L


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Resistance Form

Buccal & lingual walls ofthe occlusal part should be

parallel or slightly

convergent occlusally.

Well defined internal lineangles.

BL


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Resistance Form

About 1.5-2 mm pulpal

depth.

1.25 -1.5 mm

mesiodistally.

1.5-2.0 mm

MD


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Resistance Form

Parallel or slightly convergent

buccal & lingual walls of the

box.

Well defined internal line angles

& point angles.

Buccal & lingual proximal walls

should meet the external

portion o the tooth at 90.

S shaped or reverse curve

buccal outline.


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Resistance Form

The axial wall should be

just inside the DEJ, about1.25 mm in depth.

The buccolingual contour of

the axial wall should be

parallel to the proximal

surface of the tooth.

B

L


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Resistance Form

Rounded pulpoaxiall

line angle.

Gingival wall is

horizontal.


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Retention Form

Occlusal.

Proximal: Retention grooves.

Inside the DEJ along the

buccoaxial & linguoaxial line

angles.

The groove extend from thegingival floor to the pulpal

floor.


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Retention is made with

(small) round bur.

Retention grooves aid in

retention as well as

strengthen the restoration.


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Class V Amalgam Preparation

Outline Form

Usually determined by the extent of

caries.

All carious lesion & decalcification thatis not hard should be included.

Occlusal cavosurface margin should

be parallel to the occlusal table &

gingival cavosurface parallel to the

gingival floor.

About 4 mm wide mesiodistally & 2

mm wide occlusogingivally.


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Resistance Form

Mesio & distal walls aredivergent toward the external

tooth surface.

The occlusal & gingival walls are

parallel.

The axial wall is just inside the

DEJ, 1.5 mm deep at the

occlusal wall, 1.0 mm at gingival.

The axial wall is convex parallel

to the external surface of the

tooth.


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Retention Form:

Retention grooves in

dentin of the occlusal &

gingival walls near the

internal line angles.

The grooves should not beplaced in the mesial &

distal walls.


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Amalgam Mixing & Placement

1. Mixing the amalgam

2. Placing the amalgam in the cavity

3. Carving & burnishing the amalgam

4. Polishing the amalgam


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Mixing the Amalgam

Trituration of amalgam includes combining or mixing the

mercury with the alloy powder.

Electric amalgam mixers (amalgamators).

Amalgam pellets & bottled mercury is still in use.

Precapsulated amalgam alloy is recommended:

- Provide more consistent mix.

- Eliminate the possibility of mercury spills.


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The duration and speed of trituration of amalgam shouldbe just enough to coat all the alloy particles with mercury.

Over mixing of the amalgam will set prematurely & thiswill prevent enough condensation & adaptation of theamalgam.

Overmixed amalgam is dry & coherent.

Undermixed amalgam is dry , but crumbly.


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Well mixed amalgam is

shiny & coherent.

Mixed amalgam is placedin the amalgam well.

Amalgam should be used

directly after mixing.


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Condensation of the Amalgam

Condensing is the

process ofcompressing &

directing the amalgam

in the cavity with the

amalgam condenser.


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Amalgam carrier is used

treo carry the amalgam

in increments to the

cavity.

The cavity should be

overfilled & then carved

back in order to

eliminate voids &remove excess mercury.


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Amalgam should

be condensed

both vertically &

laterally to adapt

it to the walls.


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Condensation forces:

The force should be 2-5 kg for admixture &conventional amalgam.

Result in slight movement of the patients mandible

or head.

Less condensation is required for spherical alloy.

Small condenser should be used initially & in small

areas and larger condenser for overfilling of the

restoration.


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Precarve Burnishing

Burnishing prior to carving with large burnisher.

Immediately after condensation.

Heavy strokes in the mesiodistal & buccolingualdirection.

Produce denser amalgam at the margins of the

restoration.

The first step in shaping the occlusal surface of

the restoration.


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Carving of Amalgam

Carving should createcontours & occlusion thatreproduce the missingtooth structure.

The carver should rest onthe enamel adjacent tothe preparation and be

pulled in a directionparallel to the margin ofthe preparation.


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Carving of Amalgam

Amalgam should not be overcarved leaving thegroove anatomy deep.

If the anatomy is shallow, it may affect occlusal

masticatory function or create occlusalinterferences.

Amalgam restorations should ideally have 75 to

90 degree amalgam margins.

Ideally, carving should be completed within 6minutes of amalgamation.


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Placing amalgam in Class II cavities

Matrix band &retainer.


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The Universal Tofflemire Retainer

Straight & contra-angled

Tofflemire retainer.


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Parts of the Tofflemire Retainer1. Set screw

2. Rotating spindle

3. Slide

4. Head

5. Band


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Matrix Band

Ideal Properties of the Matrix Band

Easy to apply & remove. Extend below the gingival margin.

Extend above the marginal ridge height. Resist deformation during material

insertion.


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Shapes of Matrix bands:

Universal matrix band (# 1).

# 2 (MOD) band.

# 3 band.


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Wedge:

Obtain a tight proximal

contact.

Obtain proper interproximal

contour.

Prevent gingival overhang.

Other uses of the wedge: Protect the gingiva during

preparation.


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Many different shapes& sizes of plastic and

wooden wedges.

Most commonly used isthe triangular shape.

The wedge is placed in

the wider embrasure,usually the lingual.


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Correct Position of theWedge:

The base of the wedge

should be gingival to the

gingival margin.


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Incorrect Position of the

Wedge

Can cause concavity

in the matrix, and this

concavity can transfer

to the amalgam.


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Tofflemire Retainer & Wedge in Position


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Postcarve Burnishing Light rubbing of the carved

amalgam with a burnisher

to smooth the surface of therestoration.

The amalgam can be wiped

with water-damp cotton rollfor additional smoothening.


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Adjusting the Occlusion

Occlusion should be checked with an articulating

paper.

Ask the patient to very gently to tap the

posterior teeth together.

Interferences should be checked first in maximum

intercuspation, and then in eccentric movements.


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Amalgam Polishing

Reasons for polishing:

1. Improve oral hygiene since smooth surfaces & marginsaccumulate less plaque.

2. Removal of overhangs that can irritate the gingivaltissues.

3. Occlusion & occlusal anatomy can be refined.

4. Corrosion is inhibited, therefore extending the life of therestoration.

5. The esthetic of a polished, light colored restoration isbetter than tarnished, blackened restoration.


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Amalgam Polishing

Should be done at asucceeding appointment, or atleast several hours afterplacement of the restoration.

The restoration should bechecked first for defects oroverhangs.

Gross smoothening & refining

of occlusal anatomy should beaccomplished first with stoneor finishing burs.


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Amalgam Polishing

Abrasive-impregnated

rubber cups & points

are used forsmoothening &

polishing.

Amalgam Restorations II

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