Uploaded byParamita Brahmachari
procedure for amalgam restoration
The document provides information on the procedure for amalgam restoration. It discusses the appropriate mercury to alloy ratio, which is typically 1:1. It describes the steps of trituration to mix the alloy and mercury using either hand mixing or mechanical mixing. Proper trituration is important to coat the alloy particles. The document also outlines the steps for condensing the amalgam into the cavity preparation using incremental layering and discusses carving and polishing the final restoration.
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procedure for amalgam restoration
- 1. Procedure for Amalgam Restoration Presented by- ParamitaBrahmachari (P.R.C.A)
- 2. Mercury/alloy ratio • Historicallythe only way to achieve smooth and plastic amalgam mixes was to use excess of mercury but this was discarded later considering health hazard. • for conventional mercury added system two techniques were used for achieving mercury reduction in final restoration, initially it is removed with the help of the cloth by squeezing through it. • Second techqnique- increasing dryness tchnique,during condensation of each increment a mercury rich soft layer comes to the surface. • The most obvious method to reduce mercury content is minimal mercury technique or eames technique(mercury:alloy=1:1) ,in which sufficient mercury should be present to form coherent and plastic mass after trituration. The mercury content of the finished restoration should be comparable to the original mercury/alloy ratio usually 50 wt%
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- 4. Proportioning • The amountof alloy and mercury to be used can be described as the mercury/alloy ratio which signifies the parts by weight of mercury and of alloy to be used. • The recommended mercury/alloy ratio for the lathe cut alloys is approximately 1:1 or 50% mercury, in case of spherical alloy mercury should be 42% because spherical particles have lower surface/volume ratios. • Use of little mercury results in dry mix, impairs the strength of high copper amalgam and also reduces corrosion resistance. • Dispenser should be held vertically to ensure consistent spills of the mercury, tilting the bottle 45-degree results in unreliable mercury/alloy ratios and the dispenser should be half full when used.
- 5. Trituration • The objectiveof trituration is to provide proper amalgamation of the mercury and the alloy. The alloy particles are coated with a film of oxide which is removed by abrasion when alloy particles and mercury are triturated • Types- hand mixing mechanical mixing
- 6. Hand mixing • Aglass mortar and pestle are used. • The mortar has its inner surface roughened to increase the friction . • Usually a period of 25 to 45 second is sufficient for hand mixing. MORTAR AND PESTLE
- 7. Mechanical trituration The disposablecapsule serves as a mortar and the cylindrical metal placed in the capsule serves as the pestle. The alloy and mercury are dispensed into the capsule ,it is secured in the machine and the machine is turned on. There is an automatic timer for controlling the mixing time. • Mordern amalgamator has two or more operating speeds. • The mulling process generally causes the mix to cohere so that it can be readily removed from the capsule. • Spherical alloy require less amalgamation time than lathe-cut alloys, amalgamation time also depends on the quantity. • For a given alloy/mercury ratio increased trituration time and speed shortens the working and setting time. Amalgamat or
- 8. UNDER TRITURATED MIX roughand grainy and may crumble tarnish and corrosion can occur strenght is less mix hardens too rapidly excess mercury present NORMAL MIX Shiny surface,soft and smooth consistency Warm when removed from capsule Best compressive and tensile strenght Has luster after polishing Increased resistence to tarnish and corrosion OVER TRITURATED MIX Soupy mix,difficult to remove from capsule Working time increased Higher contraction of amalgam Creep is increased
- 9. Consistency • Proper combinationof the alloy and mercury is a prime manipulative consideration, the composition of the final amalgam is the major determinant of the physical properties. • Proper mix retains its luster longer after polishing and also remains warm when it is removed from the capsule.
- 10. MULLING Mulling is actuallya continuation of trituration. It increases the homogenity of the mass and get a single consistent mix. The mix is enveloped in dry piece of rubber dam and rubbed between the first finger and thumb,or the thumb of one hand and the palm for 2-5 sec.
- 11. Armamentarium Amalgam Condensers Anatomic Burnishers Carves — Cleoid or Discoid
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- 13. condensation • The goalof condensation is to compact the alloy into the prepared cavity so that the with sufficient mercury present to ensure complete continuity of the matrix phase between the remaining alloy particles. • After the mix is made condensation of the amalgam should be promplty initiated, condensation of partially set material probably fractures and break up the matrix that has already formed. • Condensation should be as rapid as possible and a fresh mix of amalgam should be made if condensation takes longer than 3-4 mins. • The field of operation should be dry before application.
- 14. Hand condensation • Oncethe increment of amalgam is inserted into the cavity preparation it should be condensed with pressure to avoid voids and to adapt the material to the walls, the condenser point is forced into the amalgam mass under hand pressure. • Condensation is started at the center and then condenser point is stepped little by little towards the cavity wall. • After condensation of the each increment excess mercury should left over the first increment so that it can bond with the next increment. • The procedure of adding an increment,condensing it,adding another increment and so forth is continued until the cavity is overfillled. • In case the cavity is large well condensed amalgam restoration can be achieved when the mix has proper consistency. Hand condenser
- 15. Contd…. • Size ofthe increments should be small.in larger piece of increment it is difficult to reduce the voids and to adopt the alloy to the cavity walls. • Sufficient condensation force should be used to force the alloy particles together and to reduce voids,and work mercury to the surface to achieve bonding between the increments.
- 16. Condensation pressure When agiven force is applied,smaller the condenser greater the pressure exerted on the amalgam. . For eg-when a thrust of 40N exerted with the help of the 2mm diameter results in condensation pressure 13.8MPa, the same thrust produce by 3.5mm in diameter produces 4.6MPa pressure, although forces as great as 66.7N is acceptable. • Serrated condenser is preferred than round condenser in case of the corner of the cavity. • The shape of condenser points should conform to the area under condensation. • eg- a round condenser is ineffection in the corner of the cavity,a triangular or rectangular is indicated in such areas.
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- 19. Start with thesmallest condenser
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- 23. Mechanical condensation It differs fromhand condensation such that it is performed by an automatic device. Various mechanics are employed for such instruments- some provide impact type of force and some use rapid vibration.. Less energy is required than hand condensation and the dentist feels less fatigue.
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- 27. Carving and finishing •After amalgam is condensed in cavity it is carved to reproduce the proper tooth anatomy. It should be started when the amalgam is hard enough to offer resistance to the carving. • Burnishing of the occlusal anatomy can be accomplished with the help of the ball burnisher. A rigid flat-bladed instrument is best used on the smooth surfaces. Final smoothing can be done with the help of moist cotton or with the help of prophylaxis paste. While polishing temp should not raise beyond 60-degree. • Final finish should be done after the amalgam is fully set,it should be delayed for at least 24 hr. and a wet prophylaxis paste should be used .
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- 31. Final shape andburnishing
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- 33. Initial Condensation Class IIrestoration
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