3. Direct Restoration with Amalgam (Dr. Hack)

Indications for Amalgam

• Posterior teeth: Class I, Class II and Class V

• Anterior Teeth: some distal canine Class III

• Abutment surfaces for removable partial denture

• Interim restorations in caries control

• Core buildups (for crowns) and retrograde root fillings

Contraindications of Amalgam

• Mercury Sensitivity (rare)

• Esthetically prominent areas

• Small class I, II and V that can be filled with composite or glass ionomer

Where can Mercury be found in the Environment?

• Vapor from incorrect processing

• Water lines

• Fish and wildlife

What are sources of mercury vapor?

• Freshly triturated amalgam

• Placement of amalgam restorations

• Removal of amalgam restorations!!!

• Leaky capsules

• Contaminated work surfaces and floors

• Heat sterilization of amalgam-contaminated instruments (clean well)

How do we minimize vapor?

• Use high-vacuum suction when removing or placing amalgam

• Use mask, gloves and protective eyewear

• Use in well ventilated area

• Use covered triturator

• Use pre-capsulated disposable alloys

• Monitor allow levels in operatories

• Remove residual amalgam from instruments before autoclaving

Who in the dental office must be trained in the correct handling and safety procedures as the highest risk of mercury toxicity is to dental personnel?

ALL PERSONEL MUST BE TRAINED

What is the proper disposal of amalgam?

• Place all scraps and opened capsules into sealed amalgam containers as per EPA regulatory policies

• Side chair traps must be checked by engineering every 3 months

What is NSU’s policy on Amalgam for patients?

• Patients must give informed consent knowing the risks and advantages of amalgam

• Students do not have any requirement including amalgam restorations

What are the 2 situations in which amalgam restorations may be considered as an option

In high caries risk patients who:

• Preparation ends on the root cementum

• Rubber dam isolation cannot be achieved

Explain microleakage and corrosion of amalgam

• Crevicular corrosion occurs at the tooth margin and the amalgam

• Chemical byproducts of corrosion are formed

• Over time microleakage of amalgam decreases due to the the presence of corrosion products formed at the margin interface

Why may marginal fracture occur in amalgam?

Because amalgam is a very brittle material with low tensile strength and creep

• Which type of amalgam is more brittle and prone to bulk fracture?

• Which type of amalgam is less prone to marginal fracture?

• High copper amalgam

• High copper amalgam

What is creep? Where does the most creep occur on an amalgam restoration?

• Creep is the plastic deformation of a material over time that results in volume increase over time, bulges out

• The most creep occur in non-occlusal surfaces

How does Zinc affect Creep?

High copper amalgams that contain zinc do not exhibit delayed expansion

Why is isolation important on amalgam restorations?

Because moisture creates porosities, which will decrease the strength and increase corrosion and creep

In order to prevent amalgam fracture, what are the guidelines for preparations?

• Minimum depth must be 1-2mm to prevent bulk fracture

• Cavosurface margin must be 90 degrees

• Walls must be convergent to retain

What MUST be assessed prior to placement of amalgam?

• Occlusion because we do not want the margin of the restoration to be on the margin of the restoration

What is the sequence of use of amalgam?

• Trituration and amalgamation

• Carrying, placement and condensation: must be well adapted, no voids and have as little mercury as possible; overfill, use smallest to largest condensers; 1mm increments; lateral and vertical pressure

• Pre-carving burnishing: form of condensation that covers margins, creates initial anatomy, removes gross excess and brings mercury rich phase to the surface

• Carving: create primary anatomy and remove sharpness

• Post-Carving burnishing: light rubbing used to smooth surface and should be avoided at margins

• Finishing and Polishing: rub cotton on surface achieve smooth surface, complete polishing 24-48 hours later

What is the timeframe of these:

• Trituration

• Working time

• Setting time

• Trituration → 9-11s

• Working time → 3.5m

• Setting time → 4.5m

Define Amalgamation and Trituration

• Amalgamation: the process of mixing liquid mercury with one or more metals

• Trituration: process of grinding a powder within a liquid

• Used interchangeably

Always burnish from ______ to _______

amalgam to enamel