MANIPULATION OF AMALGAM.pptx

Manipulation of Dental Amalgam

1. MANIPULATION OF AMALGAM YARTI LONGKUMER 2 ND YEAR BDS REGIONAL DENTAL COLLEGE & HOSPITAL, GUWAHATI

2. CONTENT ALLOY SELECTION POWDER AND LIQUID PROPORTIONING TRITURATION Hand Trituration Mechanical Trituration Trituration Consistency MULLING CONDENSATION SPEEED OF PLACEMENT PRE- BURNISHING CARVING POST-BURNISHING FINISHING AND POLISHING

3. ALLOY SELECTION ACCORDING TO COPPER CONTENT: High-Cu Unicomposition , High-Cu Admixed , Low-Cu    ACCORDING TO ZINC CONTENT: Zn containing , Zn-free  ACCORDING TO PARTICLE SIZE: Lathe-cut , Sphereical , Spheroidal   

4. SUPPLIED AS: DISPENSERS TABLETS PREPROPORTIONED CAPSULES

5. PROPORTIONING EAMES TECHNIQUE (Mercury: Alloy - 1:1) However, it is still necessary to squeeze mercury out of the mix using the increasing dryness technique. Hence, with this technique, 50% or less mercury will be in the final restoration, with obvious advantages. Mercury alloy ratios ranges from 43 to 54%. In pre-proportioned capsule the mercury/alloy ratio is determined by the manufacturer and is usually less than 50%.

6. TRITURATION Trituration is the process by which mercury is allowed to react with the alloy powder. This procedure allows the rubbing of the surface oxide on amalgam particles, exposing an active surface to react with mercury. OBJECTIVE: To provide proper amalgamation of the mercury and Alloy TRITURATION

7. TRITURATION HAND TRITURATION A glass mortar and pestle is used. The mortar has its inner surface roughened to increase the friction between amalgam and glass surface with carborundum paste. A pressure of 2-3 psi should be applied

8. TRITURATION MECHANICAL TRITURATION: The disposable capsule serves as a mortar. Some capsules have a cylindrical metal or plastic piece in the capsule which serves as the pestle. Reusable capsules are available with friction fit or screw – type lids. Amalgamators have automatic timer and speed control device. The speed ranges from 3200 to 4400 cycles per minute. High copper alloys require higher mixing speed.

9. EFFECT OF DIFFERENT TRITURATION CONSISTENCY UNDER TRITURATED Grainy appearance Restoration will be weak It gives a rough surfaces after carving and increases susceptibility to tarnish and corrosion. Strength is less Mix hardens too rapidly and excess mercury remains. OVER TRITURATED Shiny and soupy appearance. Working time is decreased. Results in higher conc. of Amalgam. Strength increases from lathe cut alloys, whereas it decreases in high copper alloys. Creep is increased. NORMAL TRITURATED Shiny Surface and smooth and soft consistency. It has the best compressive and tensile strength. Carved surfaces retains its lustre after polishing. Hence increase resistance to tarnish and corrosion It may be warm when removed from the capsule

10. MULLING Mulling is actually a continuation of trituration. It is done to improve the homogeneity of the mass and get a single consistent mix. It can be accomplished in two ways:  The mix is enveloped in a dry piece of rubber dam and vigorously rubbed between the first finger and thumb, or the thumb of one hand and palm of man other hand for 2-5 seconds.  After trituration the pestle is removed and the mix is triturated in the pestle-free capsule for 2-3 seconds. Mulling is not necessary for mechanical triturated amalgams.

11. CONDENSATION The amalgam is placed in the cavity after trituration, and condensed using suitable instrument. Proper condensation increase the strength and decrease the creep of the amalgam. Condensation must always be done within the four walls and floor. If one or more walls of the cavity are missing, a steel matrix may be used to compensate for it. INSTRUMENTS USED: Amalgam Carrier Round Condenser

12. CONDENSATION

13. MANUAL CONDENSATION The mixed material is condensed in increments. Each increment is carried to the prepared cavity by means of a small forceps or an amalgam carrier. Once inserted, it should be condensed immediately with sufficient pressure (approximately 3 to 4 psi).

14. MECHANICAL CONDENSATION Mechanical condensers provide vibration or impact type of force to pack the amalgam mix. Less effort is needed than for hand condensation.

15. SPEED OF PLACEMENT Once amalgam is triturated, phase formation commences and the setting reaction is underway. Amalgam must be placed in a plastic state No amalgam should be placed more than 3 minutes after the start of mixing. Attempting to condense a partly set amalgam into a cavity will result in Poor adaptation, Reduced marginal seal and A weak restoration.

16. PRE-CARVE BURNISHING  Carried out using a large burnisher for 15 seconds  Use light force and move from the center of the restoration outwards to the margins.

17. OBJECTIVES OF PRECARVE BURNISHING

18. CARVING  Using remaining enamel as a guide, carve gently from enamel towards the center and recreate the lost anatomy of the tooth.  Amalgam should be hard enough to offer resistance to carving instrument  A scraping or "ringing" (amalgam crying) should he heard.  If carving is started too soon, amalgam will pull away from margins.

19. OBJECTIVES OF CARVING: A restoration with minimal flash A restoration with proper size, location, extend and interrelationship of contact areas.

20. FINAL BURNISH (POST CARVE BURNISHING)  Following carving, check the occlusion and carry out a brief final burnish.  Use a smaller-end of the burnisher at a low load and burnish outwards towards the margins  Improves smoothness  Heat generation should be avoided If temp raises above 60°C, causes release of mercury accelerates corrosion & fracture at margins

21. FINISHING & POLISHING  FINISHING can be defined as the process, which continues the carving objectives, removes flash and overhangs and corrects minimal enamel underhangs .  POLISHING is the process which creates a corrosion resistant layer by removing scratches and irregularities from the surface.  Can be done using descending grade abrasive, eg. rubber mounted stone or rubber cups.  A metallic lusture , is always done with a polishing agent (precipitated chalk, tin or zinc oxide).

22. RUBBER ABRASIVE POINTS AND FINE ABRASIVE PASTE ADD LUSTRE

23. ADVANTAGES OBJECTIVE Removal of superficial scratches and irregularities

24. BIBLIOGRAPHY STURDEVANT’S ART AND SCIENCE OF OPERATIVE DENTISTRY PRE- CLINICAL MANUAL OF CONSERVATIVE DENTISTRY ANF ENDODONTICS – V Gopikrishna

25. THANK YOU