Cementation
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The document summarizes different types of dental cements used for cementation of restorations. It discusses the bonding mechanisms of nonadhesive luting, micromechanical bonding, and molecular adhesion. It then describes six main types of dental cements - zinc phosphate, polycarboxylate, zinc oxide eugenol, glass ionomer, resin luting, and hybrid ionomer cements - and provides key details about their compositions, strengths, weaknesses, and applications. Finally, it outlines the basic steps for cementation of a restoration, including mixing the cement, coating the crown, placement on the tooth, removing excess, and ensuring proper contacts.
Cementation
- 1. CEMENTATION
- 2. The mechanisms that hold a restoration on a prepared tooth can be divided into: nonadhesive (mechanical) luting, micromechanical bonding, and molecular adhesion.
- 3. Bonding Mechanisms Nonadhesive luting – served primarily to fill the gap and prevent entrance of fluids
- 4. 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
- 5. Molecular adhesion – involves physical forces and chemical bonds between molecules of two different substances
- 7. 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
- 8. 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
- 9. 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
- 10. 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
- 11. 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
- 12. 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
- 14. Mix the cement in circular motion
- 15. Consistency of the cement should not be too flowy or too sticky
- 16. A B The 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).
- 17. Insert the crown on the abutment
- 19. Proximal contacts are tested with dental floss to remove excess cement and ensure proper interproximal spaces in between teeth