RESTORING CAVITIES - AMALGAM

RESTORING CAVITIES - AMALGAM

1. An alloy of mercury with another metal

2. HISTORY

   • 1833 CRAWCOUR BROS introduced amalgam to US
   • Powdered silver coins mixed with mercury
   • 1895 GV BLACK developed formula of modern amalgam alloy
     • 1960's conventional low-copper lathe-cut alloy (smaller particles)
     • 1970's 1st single compostion spherical - Ternary system silver/tin/copper
     • 1990's mercury free alloys (Gallium) - increased corrosion

3. AMALGAM TODAY

   • conventional low copper alloys
     • Admixed high copper alloys
       • single composition high copper alloys
         • NOWADAYS copper enriched more likely to be used

4. WHY AMALGAM?

   • Inexpensive and easy to use
     • Proven track record >100yrs
       • Less allergies than composite

5. THERAPIST CONTROLLED VARIABLES

   • TRITURATION - mixing time
     • Over - decreases working time
     • Under- crumbly mix
   • CONDENSATION - packing material
     • Lathe cut - small cd, high force
     • spherical alloy - large cd, less sens to force
     • Admixture alloys - intermediate handling between both above
     • CONDENSING RULES!
       • Condenser must fit!
       • place in small increments
       • heavy pressure
       • Overpack then carve
   • CARVING RULES
     • Carve back to cavity outline
     • Remove Hg rich layer
     • simulate anatomical form
     • smooth amalgam/enamel junction
     • Check occlusion

6. POLISHING AMALGAMS

   • 24HRS AFTER SETTING
     • smooth, less plaque retention, less corrosion

7. BONDED AMALGAM RESTORATION

   • When there is not enough tooth substance to allow amalgam eg missing cusps
   • to complete marginal seal - prevent ingress of bacteria and protects pulp

8. ADVANTAGES OF BONDED AMALGAM

   • No need for retentive feature
     • No need to use pins
     • Reduced marginal leakage and post op sensitivity
     • Reinforcement of tooth structure

9. DISADVANTAGES

   • Time consuming
     • More expensive than traditional amalgam

10. TECHNIQUE

    • Vitrebond liner, etch prime and bond
      • place chemical cure resin based luting cement
        • pack and carve amalgam

11. AMALGAM TOXICITY

    • TOXICITY - mainly from mercury
      • ALLERGY- contact derm Lichen planus
        • MERCURY POISONING
          • headaches,GI upsets, dyspepsia,tremors
        • salivation/xerostomia, severe gingivitis, fatigue, odema of face and ankles