Cementation
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Cementation

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Cementation Cementation Presentation Transcript

  • CEMENTATION
  •  The mechanisms that hold a restoration on a prepared tooth can be divided into: nonadhesive (mechanical) luting, micromechanical bonding, and molecular adhesion.
  • Bonding Mechanisms Nonadhesive luting – served primarily to fill the gap and prevent entrance of fluids
  •  Micromechanical bonding – necessary deep irregularities can be produced on enamel surfaces by etching with phosphoric acid solution or gel; on ceramics, by etching with hydrofluoric acid; and on metal, by electrolytic / chemical etching, and sandblasting
  •  Molecular adhesion – involves physical forces and chemical bonds between molecules of two different substances
  • TYPES OF CEMENTS
  • 1. Zinc Phosphate Cement possesses high compressive strength exhibits a pH of 3.5 at the time of cementation which contributes to pulpal irritation needs cavity varnish to reduce exposure of pulp to the cement
  • 2. Polycarboxylate Cement higher tensile strength (resistance to lengthwise stress) pH is also low (4.8) cause little pulpal irritation shows moderately high bond strength to enamel and dentin bonds to stainless steel, but not to gold
  • 3. Zinc Oxide Eugenol cause no pulpal inflammation as long as they make no direct contact with the pulp used as temporary cements soluble than zinc phosphate deteriorates more rapidly in the mouth than other cements
  • 4. Glass Ionomer Cement composed mainly of calcium fluoro- aluminosilicate glass compressive strength and tensile strength are quite good bacteriostatic releases fluoride at a greater rate than silicate cement pH is lower than zinc phosphate which cause post -varnish is not recommended cementation -weakened by early hypersensitivity exposure to moisture
  • 5. Resin Luting Cement composed of resin matrix and a filler of fine inorganic particles low filler content and low viscosity virtually insoluble and much stronger than conventional cements high tensile strength makes them useful for -problems encountered micromechanically include excessive cement bonding etched ceramic film thickness, marginal veneers leakage because of setting dentin bonding agent is shrinkage, and severe pulpal necessary prior to resin reactions when applied to cement application vital dentin
  • 6. Hybrid Ionomer Cements glass filler particles react with the liquid during the hardening process combined the strength and insolubility of resin with the fluoride release of glass ionomer
  • STEPS INCEMENTATION
  • Mix the cement in circular motion
  • Consistency of the cement should not be too flowy or too sticky
  • A BThe inner walls of the crown are coated with a thin layer of cement using the small end of an instrument (A) or a brush (B).
  • Insert the crown on the abutment
  • Remove excess cement
  • Proximal contacts are tested with dental floss toremove excess cement and ensure properinterproximal spaces in between teeth