Amalgamizer: Properly Triturated Amalgam Mix Quiz and Flashcards

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Questions and Answers

What is the primary reason for squeezing the mixed amalgam in a small clean piece of gauze?

To reduce the mercury content of the restoration (correct)

To ensure standard optimum results

To improve the homogeneity of the mass

To distribute the mercury contents evenly

What is the purpose of mechanical trituration using amalgamators?

To redistribute the mercury contents

To ensure standard optimum results (correct)

To accurately proportion the alloy and mercury

To improve the homogeneity of the mass

What is the purpose of the 'mulling' process?

To improve the homogeneity of the mass (correct)

To reduce the mercury content of the restoration

To eliminate excess mercury

To ensure accurate proportioning of alloy and mercury

What is the main objective of the condensation process?

To eliminate excess mercury Signup and view all the answers

What is the primary purpose of using amalgamizers?

To accurately proportion the alloy and mercury Signup and view all the answers

Why is the mixed amalgam never to be touched with bare hands?

Because mercury is toxic Signup and view all the answers

What is the recommended type of amalgam alloy for restoring a tooth that has undergone pulp capping?

Spherical amalgam Signup and view all the answers

If a cusp is undermined and needs to be capped with amalgam, what is the minimum reduction required?

2 mm Signup and view all the answers

What is the primary factor that determines the amount of alloy and mercury to be used in an amalgam restoration?

The size of the cavity Signup and view all the answers

In compound cavities, how should the retention of auxiliary portions be achieved?

By providing adequate self-retention Signup and view all the answers

What is the recommended form of alloy supply for situations where moisture contamination is a concern?

Zinc-free alloys Signup and view all the answers

Which of the following steps is NOT mentioned in the manipulation of amalgam?

Etching Signup and view all the answers

What should cavity preparations for amalgam restorations ideally have?

Conservative outlines excluding centric holding areas Signup and view all the answers

In amalgam restorations, what is the recommended depth of the gingival floor in compound cavities?

1.5 mm Signup and view all the answers

For class II cavities, what is the angle requirement for the cavo-surface in amalgam restorations?

90 degrees Signup and view all the answers

What feature should amalgam cavities ideally have in relation to the direction of occlusal forces?

Walls perpendicular to occlusal force direction Signup and view all the answers

What is the minimum width of the isthmus area in amalgam cavities?

One quarter of the bucco-lingual distance Signup and view all the answers

What technique can be used to increase the depth of the isthmus area in amalgam cavities?

Saucering the pulpal wall Signup and view all the answers

What is the primary purpose of trituration in the context of dental amalgams?

To remove surface oxides from alloy particles Signup and view all the answers

Which factors determine the amount of trituration required?

Time, speed, and pressure Signup and view all the answers

What is the consequence of under-trituration?

Dull and overly soft amalgam mixture Signup and view all the answers

Which statement best describes the characteristics of an over-triturated amalgam?

Fast setting with higher early strength and smoother surface Signup and view all the answers

Which method of trituration involves the use of a mortar and pestle?

Manual trituration Signup and view all the answers

What is an indicator of a properly mixed amalgam during manual trituration?

The mixture climbs along the walls of the mortar (curling) Signup and view all the answers

What should be done if the amount of filling required exceeds what can be condensed in 3-5 minutes?

Use more than one mix Signup and view all the answers

Why is the alloy/mercury ratio gauged by weight rather than volume?

Because volume per weight differences are caused by variation in size and form of alloy particles Signup and view all the answers

What is the consequence if there is less mercury than required to wet every alloy particle?

Some particles will remain uncoated and not be bound to the rest of the structure Signup and view all the answers

What is the consequence of having excess mercury in the final restoration?

Increased formation of the 2 phase Signup and view all the answers

What is the most obvious method for reducing the mercury content of the restoration?

Reducing the original alloy/Hg ratio Signup and view all the answers

What is the Eames technique for proportioning the alloy/mercury ratio?

Alloy/Hg ratio of 5:5 or 1:1 by weight Signup and view all the answers

Study Notes

Amalgam Restoration

Rounding of the axiopulpal line angle and all line angles is essential.
If a cusp is undermined and needs to be capped with amalgam, it must be reduced to a minimum of 2 mm.
Every portion of compound cavities should have adequate self-retention; auxiliary portions should not depend on principle portions for retention.

Manipulation of Amalgam

Selection of alloy and mercury is crucial.
Proportioning, trituration, condensation, carving, and finishing and polishing of the restoration are essential steps.

Selection of Alloy

Spherical amalgam provides soft consistency, requiring light condensation force, and is recommended for restoring pulp-capped teeth and adapting around pins.
High copper amalgam provides high strength and is used for extensive restorations.
Moisture contamination requires the use of Zinc-free alloys to prevent delayed expansion.
Alloys are supplied in the form of tablets, powder, and capsules.

Proportioning of Alloy and Mercury

The amount of alloy and mercury to be used depends on the amount required to slightly overfill the cavity, the amount that can be condensed within a limited period of 3-5 minutes, and gauged by weight.
If the cavity requires an amount in excess of what can be condensed in 3-5 minutes, more than one mix should be utilized.

Alloy/Mercury Ratio

The amount of mercury should be enough to wet every alloy particle.
If less mercury is used, some particles will remain uncoated, resulting in a non-coherent, friable mix that is difficult to condense.
If excess mercury is used, more Hg will be left in the final restoration, resulting in increased formation of γ2 phase, reduced bond between the non-consumed particles and the different phases, and reduced strength, increased expansion, decreased hardness, and increased flow and creep.

Trituration

The amount of trituration is a function of time, speed, and pressure, and must be standardized.
Undertrituration results in some particles remaining covered with oxides, uncoated with or bound to the structure, with excess of residual Hg remaining, resulting in a weak, corrodible, and excessively expanding amalgam.
Overtrituration results in a less plastic, yet homogeneous and coherent mix of amalgam, setting fast as a result of rapid Hg consumption and crystallization of produced phases, resulting in a fast-setting and contracting amalgam with higher early strength and smoother surface.

Methods of Trituration

Manual trituration involves the use of a mortar and pestle.
Mechanical trituration involves the use of amalgamators or amalgamizers.

Condensation

Definition: The process of forcible packing of fresh triturated mix into details of prepared cavity with objectives including elimination of excess mercury and minimizing voids.

Cavity Preparation

Amalgam is a brittle material, and cavity preparations should have:
- Conservative outlines, excluding centric holding areas, if possible.
- Adequate bulk for strength, which depends on an increase in cross-sectional areas.
- A resistance-retention form.
Amalgam cavities should have specific features, including:
- Cavo-surface angle of 90 degrees.
- Cavity walls parallel or perpendicular to the direction of occlusal force of mastication.
- A definite gingival floor, 1.5 mm deep from the surface and 0.2 mm deep in dentin in compound cavities.
- An isthmus area of minimum width of one quarter the bucco-lingual distance between cusp tips and an increased depth.

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Description

Learn about dental amalgam, its advantages, disadvantages, indications, contraindications, classification of amalgam alloys, and cavity preparation techniques. Explore the importance of conservative outlines and resistance-retention form for amalgam restorations.

Dental Amalgam Restorations: Classification and Cavity Preparation

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