Dental cement dental material

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Dental cement dental material

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Dental cement dental material

  1. 1. DENTAL CEMENTS 2014
  2. 2. Cements Substances used to glue 2 solid objects together 2014
  3. 3. 2014 In addition to the gluing function, Dental Cements own many different applications
  4. 4. 2014 3 main Categories
  5. 5. 2014 Zinc Oxide Alumino Silicate Glass Phosphoric Acid Polyacrylic Acid Eugenol ZOE & Ca(OH)2 Zinc Polycarboxylate Glass Ionomer Silicate Zinc Phosphate Cements set via Acid-Base Rx
  6. 6. ZINC OXIDE EUGENOL (ZOE) CEMENT 2014
  7. 7. 2014 Presentation forms Powder Liquid • Zinc oxide • Magnesium oxide • Zinc Acetate- Accelerator • Eugenol • Olive oils • Acetic acid- Accelerator Two paste system (Base & Catalyst) Eugenol-Containing Eugenol-Free Single paste – sets in contact with water
  8. 8. 2014 How it sets? via acid-base Rx (Chelation) • ZnO + H2O  Zn(OH)2 (1) • Zn(OH)2 + E  Zinc Eugenolate (2) Mixing on either paper pad or glass slab using a stainless steel spatula at high P/L ratio (4 :1) • Thin mix  for temp. cementation • Thick mix  for temp. filling Set material Matrix of zinc eugenolate (chelate) + Dispersed non-reacted Zinc oxide particles • Presence of water is essential – Saliva could help • Zinc acetate dissolves faster in water  zinc hydroxide
  9. 9. 2014
  10. 10. 2014 1. Biological Characteristics • Bacteriostatic -- kills bacteria of carious cavities • Low thermal diffusivity -- insulate thermal and electrical irritations • Obtundent effect -- reduces the pulpal pain • High sealing ability -- minimize the leakage in temp. restored cavities Material’s Characteristics (BMIECP)
  11. 11. 2014 2. Mechanical Characteristics • Weak cement -- could not withstand either masticatory forces -- could not withstand amalgam’s condensation forces 4. Esthetic Characteristics • Opaque – not used to lute translucent ceramic restorations 3. Interfacial Characteristics • Mechanically-retained -- to both tooth and restorations’ surfaces -- adapt well to cavity walls http://dentala2z.co.uk/Opt10057A2
  12. 12. 2014 5. Chemical Characteristics • Water soluable -- dissolves in oral saliva • Eluted Eugenol -- changes the color of overlying composite restoratives -- retard the polymerization of overlying composite restoratives -- swallowed E causes gastric troubles 6. Practicability • Easily mixed – no special precautions but – it is better to mix it in thick consistency
  13. 13. 2014
  14. 14. 2014 Modified Materials
  15. 15. 2014 CALCIUM HYDROXIDE
  16. 16. 2014 Presentation forms Ca(OH)2 powder Single paste – methyl cellulose- sets in air Light-cured Ca(OH)2 paste – resin matrix Two paste -- the only sets via an acid-base Rx Base Catalyst • Calcium hydroxide • Zinc oxide • Zinc Acetate- Accelerator • Liquid vehicle • di-salicylate, • Radio-opacifers, • Fillers
  17. 17. 2014 1. Biological Characteristics --- related to material’s alkalinity (pH= 11-13) • Bacteriostatic -- kills bacteria of carious cavities • Neutralizes the acids produced by the cariogenic bacteria • Help differentiate pulpal stem cells -- reparative dentin stimulator Material’s Characteristics (BMIECP) 2. Mechanical Characteristics • Weak cement -- could not withstand amalgam’s condensation forces 4. Esthetic Characteristics • Opaque – not used to lute translucent ceramic restorations 3. Interfacial Characteristics • Mechanically-retained -- does not adhere to the tooth structure 5. Chemical Characteristics • Quite soluble -- dissolves in liquids even under leaked restorations
  18. 18. 2014
  19. 19. 2014 ZINC PHOSPHATE CEMENT
  20. 20. 2014 Powder Liquid • Zinc oxide • Magnesium oxide • Other oxides & fluorides • Phosphoric acid (H3PO4) • Water (30-40%) • Buffering agents -- Zinc oxide, zinc hydroxide Presentation forms Mixing on thick, cool glass slab using stainless steel spatula powder is added to the liquid in small increments Mixing over a wide area • Thin mix  for cementation • Thick mix  for cavity base /temp. filling
  21. 21. 2014 How it sets? Through a Fast , exothermic acid-base Rx (Crystallisation) ZnO + H3PO4  Zn3(Po4)2 + H2O Set material matrix of zinc phosphate salt+ dispersed non-reacted zinc oxide particles Controlling the Rx speed (setting time) 1. ↓ Powder particle size   reaction 2.  Temperature   reaction 3. ↓ Buffers   reaction 4.  P/L ratio   reaction 5.  Mixing rate (speed or time)   reaction 6.  Acid concentration   reaction
  22. 22. 2014 1. Biological Characteristics • Pulp irritant -- fresh mix is highly acidic (pH 1.6-3.6) -- Ca(OH)2 liner is needed in deep cavities -- Thin mix is more irritant than the thick mix -- Set material becomes neutral in 48 hrs • Low thermal diffusivity -- insulate thermal and electrical irritations Material’s Characteristics (BMIECP) 2. Mechanical Characteritics • Stronger than ZOE and weaker than GI -- withstand amalgam’s condensation forces (cavity bases) -- could withstand masticatory forces ( permanent cementation /temp filling) 3. Interfacial Characteristics • Mechanically-retained -- to both tooth and restorations’ surfaces • Film thickness similar to that of zinc phosphate cement (15μm)
  23. 23. 4. Esthetic Characteristics • Opaque – not used to lute translucent ceramic restorations 5. Chemical Characteristics • Water soluble -- dissolves in oral saliva -- thin mix dissolves more than the thick mix 2014 6. Practicability • Material is successfully used for a long time • Needs well-trained operator due to its short S.T. • precautions – 1. Liquid bottle should be tightly closed all the time 2. Liquid with cloudy appearance should be discarded 3. Shake the powder bottle before dispensing the correct ratio 4. never use powder of other cements (e.g. ZOE…) or of other manufacturer
  24. 24. 2014
  25. 25. 2014 POLY-ACARYLIC ACID in comparison to phosphoric acid • Has lower acidity • Has higher molecular weight --More viscous • Bonds chemically to the inorganic part of tooth structure
  26. 26. 2014 ZINC POLYCARBOXYLATE CEMENT
  27. 27. 2014 1. Powder Liquid • Zinc oxide • Magnesium oxide • Flourides • Poly-acrylic acid (30-40%) • Water 2. Powder in a single bottle water settable material Freeze dried acid is blended with the powder 3. Capsules Presentation forms
  28. 28. 2014 Mixing On a glass slab using stainless steel spatula PAA is viscous and needs more effort during material’s mixing • Thin mix ( P/L ratio 1.5:1) for cementation • Thick mix ( P/L ratio 2.5:1) for cavity base /temp. filling How it sets? Through a acid-base Rx ZnO + PAA  Zn-polyacarylate + H2O Set material matrix of zinc polyacrylate salt+ dispersed non-reacted zinc oxide particles
  29. 29. 2014
  30. 30. 2014 1. Biological Characteristics • Pulp irritant -- fresh mix is acidic But less than zinc phosphate cement is -- Ca(OH)2 liner is needed in deep cavities -- Thin mix is more irritant than the thick one -- Set material becomes neutral in 48 hrs • Low thermal diffusivity -- insulate thermal and electrical irritations Material’s Characteristics (BMIECP) 2. Mechanical Characteristics • Its strength is comparable to that of zinc phosphate cement -- withstand amalgam’s condensation forces (cavity bases) -- could withstand masticatory forces ( permanent cementation /temp filling) 3. Interfacial Characteristics • Chemically adhere -- to the tooth and base metal restorations • Film thickness similar to that of zinc phosphate cement (15μm)
  31. 31. 2014 4. Esthetic Characteristics • Opaque – not used to lute translucent ceramic restorations 5. Chemical Characteristics • More soluble in water than zinc phosphate cement -- thin mix dissolves more than the thick mix 6. Practicability • Viscous liquid make the mixing process a little pit difficult • All metallic instruments should be cleaned up while the cement still unset • To achieve better bonding 1. Tooth surface should be cleaned and dried from saliva 2. Mixed cement should be applied to tooth structure as fresh as possible
  32. 32. 2014
  33. 33. 2014

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