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ZINC PHOSPHATE CEMENT

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ZINC PHOSPHATE CEMENT

  1. 1.  INTRODUCTION  CLASSIFICATION  AVAILABLE AS  COMMERCIAL NAME  COMPOSITION  MANUFACTURE  SETTING REACTION  PROPERTIES  MANIPULATION  ADVANTAGES  DISADVANTAGES  APPLICATION
  2. 2.  ADA SPECIFICATION NUMBER- 96.  Zinc phosphate is the oldest of the luting cements and thus serves as a standard with which newer cements can be compared.
  3. 3.  ADA Spa. No. 96. designates them as:  Type I: Fine grained for luting. Film thickness should be 25micrometer.  Type II: Medium grained for luting and filling. Film thickness should not more then 40micrometer.
  4. 4. 1. Powder and liquid system. 2. Capsules of preproportioned powder and liquid.
  5. 5.  - Confit.  - Harvard.  - Zinc Cement Improved.  - Modern Tenacin.
  6. 6. )(. POWDER: - Zinc Oxide- 90.2%. >. Principal constituent. - Magnesium Oxide- 8.2%. >. Aids in sintering. - Other Oxide- 0.2%. >.Improve smoothness of mix. - Silica- 1.4%. >.Filler.
  7. 7. )(. LIQUID: - Phosphoric Acid- 38.2%. >.React with zinc oxide. - Water- 36.0%. >.Control rate of reaction. - Aluminium Phosphate- 16.2%. >.Buffer. - Aluminium- 2.5%. - Zinc- 7.1%.
  8. 8.  The ingredients are mixed and heated at temperatures bw 1000‘C. and 1400’C. [SINTERING].  After sintering ,the cake formed is cooled quickly.  This cause the material to crack which helps in grinding of the material to a fine powder.  This process is known as FRITTING.
  9. 9. @. When the powder is mixed with liquid, phosphoric acid attacks the surface of the particles and releases zinc ions. @. The aluminum in the liquid is essential for cement formation. @. The aluminum complexes with the phosphoric acid and the zinc ions to form a zinc aluminophosphate gel.
  10. 10. @. The reaction is EXOTHERMIC. @. Setting Time: 2.5-8 mins.
  11. 11. #. COMPRESSIVE STRENGTH: 103.5MPa.[15,000GPa]. #. TENSILE STRENGTH: 5.5MPa.[800psi]. #. MODULUS OF ELASTICITY: 13.5GPa. #. SOLUBILITY: 0.06%.
  12. 12. #. THERMAL PROPERTIES: Good Thermal Insulator. #. ADHESION PROPERTIES: Not form a chemical bond with enamel or dentin. #.BIOLOGICAL PROPERTIES: -At the time of cementation the pH is 2. -Starting pH is 3.5. -After 24 hours the pH is 5.5.
  13. 13. #. OPTICAL PROPERTIES: OPAQUE.
  14. 14. 1. Stainless steel spatula and clean cool glass slab are use for mixing.
  15. 15. 2. Mixing Time:- 1 min. 15 sec. 3. P/L Ratio:- 1.4gm/0.5ml.
  16. 16. 4. The powder is added in small increments.
  17. 17. 5. Mixing is done with stainless steel spatula using brisk circular motion. 6. Each increments is mixed for 15-20 sec.
  18. 18. 7. A large area is covered during mixing in order to dissipate the exothermic heat.
  19. 19. }{. Good compressive strength. }{. Good thermal insulation ability. }{. Dose not dissolve in oral fluids.
  20. 20. }{. No chemical adhesion. }{. Pulp irritation. }{. Poor esthetics.
  21. 21. ::- Luting for restoration. ::- High strength bases. ::- Temporary restoration. ::- Luting for orthodontic bands and brackets.

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