Trituration

Trituration during amalgam manipulation. Principles of trituration

1. TRITURATION OF AMALGAM by- Snehal Dhawale and Rutuja Shewale

2. Trituration Trituration is the process of mixing the amalgam alloy powder with mercury to make amalgam.

3. OBJECTIVES OF TRITURATION To achieve workable mass of amalgam within minimum time To remove the oxide layer. To pulverize pellets into particles that can be easily attacked by mercury. To reduce particle size. To keep the amount gamma 1 or gamma 2 matrix crystals as minimal as possible, yet evenly distributed.

4. Trituration Trituration can be done by 2 methods By hand, using a mortar and pestle, or In an electrically powered machine which vibrates a capsule containing the mercury and alloy.

5. 1. Hand trituration : A glass mortar and pestle is used for hand trituration . The mortar has its inner surface roughened to increase the friction between amalgam and glass surface with carborundum paste. An alloy/mercury ratio (around 1 : 1) is often required to produce a workable mix. Care must be taken not to use excessive pressure during trituration in order to prevent splintering of alloy particles which may change the character of the mix.

6. The trituration time may have an effect on the properties of the final set amalgam. Some products require at least 40 seconds of trituration . Following trituration , it is necessary to reduce the mercury content of the mix before condensing. The excess mercury is removed from the amalgam by : 1. Squeezing the excess mercury out by using a squeeze cloth. Hand trituration :

7. Amalgam squeeze cloth Chamois leather Hand trituration :

8. 2. Mechanical trituration In this method, trituration is done with a mechanical mixing device called an amalgamator or triturator . These devices have an automatic controlled timer and speed control device. The speed ranges from 3200 to 4400 cycles per min. They work by either vibratory or oscillatory movements High copper alloys require higher mixing speed

9. Methods of mechanical trituration Mechanical trituration can be done by 3 methods 1. Following proportioning, the mercury and alloy may be placed in a reusable amalgam capsule, which is vibrated on an amalgamator. Reusable capsules are available with friction fit or screw – type lids. Some capsules have a cylindrical metal or plastic piece in the capsule which serves as the pestle Reusable Capsules, metal and plastic pestle Amalgamator

10. 2. Alternatively, mechanical mixing in a semi-automatic machine, which also proportions mercury and alloy, is possible. Hoppers Methods of mechanical trituration

11. 3. The use of disposable, encapsulated materials provided by the manufacturer are probably the most convenient and also the most expensive option. Disposable capsules Methods of Mechanical trituration

12. Advantages and disadvantages of Mechanical trituration Shorter mixing time. Most standardized and accurate procedure. Requires less mercury when compared to hand mixing technique. There is less danger of mercury spillage during amalgam handling. The recommended “no touch” procedures for handling mercury and alloy is possible if the disposable capsules are used. Wherein, t he ratio of alloy to mercury is prefixed and standardized by the manufacturer. Disadvantages: 1. Capsules are more expensive than buying the alloy powder in bulk.

13. Normal mix Appears homogenous, coherent, shiny, plastic, and climbs at the sides of the mortar (curl off) Best compressive and tensile strength Carved surface retains luster after polishing

14. Over-triturated mix This mix is soupy and difficult to manipulate. Sticks to the sides of the mortar and is not easy to condense. Results in higher contraction Creep is increased Consumes more mercury and produces more weaker phases reducing strength.

15. Effect of trituration time - Effect on working time and dimensional change Overtrituration  Decreases working time, slightly higher contraction (Same effect for both high and low copper alloys) Effect on strength Overtrituration  Increases both compressive and tensile strength in lathe-cut alloys Both over- and under trituration  Decreases both strengths in spherical alloy and admixed high-Cu alloy

16. Effect of creep Overtrituration  Increases creep Undertrituration  Decreases creep Effect of trituration time

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