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Dental Cements

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Zinc phosphate cement
Zinc polycarboxylate cement
Zinc oxide eugenol cement

Published in: Health & Medicine
  • A well-explained slide on every Dental Cements product . A good read article on types of Dental Cements: http://www.indiasupply.com/blog/article/dental-cement/
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Dental Cements

  1. 1. Cements (Zinc Phosphate Zinc Polycarboxylate & Zinc Oxide Eugenol) PRESENTED BY: ARPIT VIRADIYA GUIDED BY: DR.SANDEEP METGUD DR.DEEPALI AGRAWAL
  2. 2. Contents • Zinc Phosphate Cement • Introduction • Composition • Setting Reaction • Working & Setting Time • Physical Properties • Retention • Biological Properties • Manipulation • Applications • Zinc Polycarboxylate Cement • Introduction • Composition • Chemical Reaction • Bonding to Tooth Structure • Working & Setting Time • Mechanical Properties • Biological Consideration • Manipulation • Applications • Zinc Oxide Eugenol Cement • Introduction • Classification • Composition • Setting Reaction • Manipulation • Physical Properties • Biological Properties • Polymer reinforced ZOE • EBA and Alumina reinforced ZOE • Non Eugenol ZOE • Summary & Conclusin • References
  3. 3. Zinc phosphate cement
  4. 4. Introduction • Oldest of the luting cement • Longest clinical track record • Serves as a standard with which newer materials can be compared • Supplied as a powder and liquid.
  5. 5. Composition  POWDER  Zinc oxide - 90%  Magnesium oxide – 9-10 %  Bismuth trioxide, Barium oxide – traces sintered at temperatures between 1000deg Celsius and 1400 deg Celsius -> cake -> fine powder particle size -> setting time
  6. 6.  Liquid  Phosphoric acid  Water  Aluminium Phosphate  Zinc Phosphate (some times) Water controls the ionization reaction of acid - in turn influence the rate of acid base reaction Acid content of the liquid - 33% approximately.
  7. 7. SETTING REACTION  When the powder is mixed with liquid , the phosphoric acid attacks the surface of the particles - releases zinc ions into the liquid – aluminium, which already forms a complex with the phosphoric acid , reacts with zinc - zinc alumino phosphate gel on the surface of the remaining portions of the particles.  Water is critical to the reaction.  ZnO + H3PO4  Zn3(Po4)2 + H2O
  8. 8.  Changes in composition and reaction rates might occur due to degradation of the liquid or water evaporation from the liquid  Liquid degradation effects are exhibited as clouding of the liquid  Loss of water from acid increases the setting time
  9. 9. Working and Setting Times  Mixing time of 1.5 – 2 mins  Setting time – 2.5 – 8 mins  The following procedures can extend the setting time  Reducing P/L ratio  Mixing in increments  Prolonging the spatulation of last increment.  Cooling the glass slab
  10. 10. Physical Properties  Compressive strength :104MPa  Tensile strength:5.5MPa  Thermal conductivity : 3.11 mcal.cm/cm2.sec.K  Low water solubility 0.04wt%  More soluble in dilute organic acids  Modulus of elasticity:13.7GPa  Quiet stiff & resistant to elastic deformation Loss/Gain water content compressive tensile strength.
  11. 11. Retention Doesn’t involve reaction with surrounding hard tissue/restorative material No chemical interactions Mechanical bonding at interfaces
  12. 12. Biological Properties  Acidity of cement is quite high during the time of application - presence of phosphoric acid 2 min after the start of mixing , Ph is 2 increases rapidly reaches about 5.5 in 24 hrs  Pulpal damage can occur during first few hours.  High heat production during setting of the cement can also cause pulpal injury.
  13. 13. Manipulation  Incorporate powder - liquid  Recommended p/l ratio – 1.4gm - 0.5ml  A cool mixing slab prolongs the working and setting time Liquid dispensed onto the slab evaporation
  14. 14.  Powder -several increments  spatulated : 15 – 20 secs  smaller quantities - first few increments – working - setting time.  middle of the mixing – larger amounts of powder– to further saturate the liquid with newly formed zinc phosphate.  Finally , smaller increments are added – so that the desired ultimate consistency of the cement is not exceeded  begins & ends with small increments
  15. 15. Applications  Luting permanent restorations  Bases  Cementation of orthodontic bands  Provisional restoration
  16. 16. Zinc Polycarboxylate Cement
  17. 17. Introduction  Zinc polyacrylate cement  First - adhesive bond to tooth structure.  Supplied as  Powder and liquid
  18. 18. Composition  Powder Zinc oxide – 72% Basic ingredient Magnesium oxide – 7% Modifier , aids in sintering Other oxides like bismuth and aluminium Stannous fluoride Increase strength, modifies setting time, imparts anticariogenic properties
  19. 19.  Liquid  Liqueous solution of polyacrylic acid (32-48%) Or  Copolymer of acrylic acid with other unsaturated carboxylic acids (itaconic , maleic , tricarballylic acids)  Molecular weight – 25,000 – 50,000
  20. 20. Chemical reaction  When acid comes in contact with powder , acid reacts and releases zinc, magnesium, and tin ions  They bond to the polymer chain , through the carboxyl groups  These ions also react with carboxylic groups of adjacent poly acid chains  Cross inked salts are formed
  21. 21. Bonding to tooth structure  Poly acrylic acid reacts with calcium ions via carboxyl groups on the surface of enamel or dentin.  Bond strength greater on enamel than dentin.  Enamel 3.4-13.1MPA Dentin 2.07MPA
  22. 22. Working and Setting time  Working time : 2.5 min  Setting time : 6-9 min  Lowering the temperature of chemical reaction can increase the setting time.
  23. 23. Mechanical Properties  Comprssive strength : 55-67 Mpa  Tensile strength : 2.4-4.4 Gpa  Modules of elasticity is lower then zinc phosphate cement 5.1GPa  More soluble than zinc phosphate cement 0.06%  More soluble in organic acids.  Not as brittle as zinc phosphate cement  Excess removal is difficult.
  24. 24. Biological Consideration  Pulpal response termed as mild  Ph of liquid is 1- 1.7  Freshly mixed cement – 3-4  After 24 hrs – 5 -6
  25. 25. Manipulation  A cooled glass slab / powder  1.5 parts of powder to 1 part of liquid by weight  Liquid not dispensed , before the start  Loss of water, increases viscosity  Powder is rapidly incorporated into the liquid in large quantities  Mixing time is with in 30 – 60 sec ,with half to all of powder incorporated at once to provide the maximum length of working time  Surface - glossy , acid present to provide sufficient carboxylic groups to bond.
  26. 26. Glossy Appearance Dull Appearance
  27. 27. Applications  Primarily for luting permanent restorations  As bases and liners  Cementation in orthodontic treatment
  28. 28. Zinc Oxide Eugenol Cement
  29. 29. Introduction  These cements have been extensively used in dentistry since 1890’ s  They are least irritant of all dental cements  Have an obtundant or sedative effect  Compatible with the hard and soft tissues of the mouth
  30. 30. Classification  Type 1 ZOE – for temporary cementation  Type 2 ZOE – permanent cementation  Type 3 ZOE – temporary filling material , thermal insulation  Type 4 ZOE – Cavity liners
  31. 31. Composition  Powder Zinc oxide – 69% Principle ingredient White rosin – 29.3% Reduce brittleness Zinc stearate – 1% Accelerator , plasticizer Zinc acetate – 0.7% Accelerator , improves strength Magnesium oxide Added in some powders
  32. 32.  Liquid:  Eugenol – 85% - reacts with zinc oxide  Olive oil – 15% - plasticizer
  33. 33. Setting reaction  First , hydrolysis of zinc oxide to its hydroxide  Water is essential for reaction to proceed  reaction is a acid base one,  Zinc hydroxide combines with eugenol to form a chelate ZnO + H2O → Zn(OH)2  ZINC EUGENOLATE  Forms an amorphous gel, which later tends to crystallize.  Structure : particles of unreacted zinc oxide embedded in a matrix of zinc eugenolate Zn(OH)2 + 2HE → ZnE2 + 2H2O
  34. 34. Manipulation  p/l ratio 4:1 to 6:1 by wt  the bulk - incorporated into the liquid -spatulated thoroughly in a circular motion - a stiff bladed spatula  Small increments - until the mix is complete – consistency
  35. 35.  Setting time - 4-10 mins  Complete setting reaction between zinc oxide and eugenol takes about 12 hrs Factors affecting setting time:  Particle size – smaller particle size, set faster  Accelerators – alcohol , glacial acetic acid , and small amounts of water  Retarders – glycol, glycerine  Temperature – high temperature , accelerate setting  Powder/ liquid ratio – higher the ratio, faster the set
  36. 36. Physical properties  Relatively week cements  Compressive strength : Ranges from 3-4mpa to 50- 55mpa  Tensile strength : 0.32 to 5.8mpa  Modules of elasticity : 0.22 – 5.4 mpa  Excellent thermal conductivity  Solubility of the set cement is high - disintegrate in oral fluids - Solubility is reduced by increasing p/l ratio
  37. 37. Biological properties  Least irritating of all dental cements  Ph is 6.6 – 8  Pulp response is termed as mild  They inhibit the growth of bacteria , have an anodyne or soothing effect on pulp , in deep cavities, hence reduces pain
  38. 38. Modified Materials  Polymer reinforced ZOE  introduced in an effort to increase the mechanical properties of zoe.  Contains Zinc Oxide and finely divided natural or synthetic resin like poly methyl methacrylate resulting in good strength, improved abrasion resistance and increased toughness  Luting agent, Base, temporary filling material and as a cavity liner.
  39. 39.  EBA and alumina modified ZOE cement  Powder :  ZnO 70%  Alumina 30%  Liquid:  EBA 62.5%  Eugenol 37.5% Properties are better than unmodified zoe Compressive strength increased 55 mpa Tensile strength – 4.1mpa Modulus of elasticity – 2.5 gpa Solubility and disintegration – 0.05% wt
  40. 40.  Non eugenol Zinc Oxide cement  Suitabe for patients sensitive to eugenol.  Eugenol acts as an inhibitor for free redical polymerized materials
  41. 41.  ZOE based periodontal pack  It protects the wound from mechanical trauma and stabilize the surgical site.  It also prevents post operative hemorrhage and infection; decreases tooth hypersensitivity in first few hours after suurgery.
  42. 42. Conclusion  Though cements are used in small quantities in oral cavity, it should be used with at most care, as it is very important. There are innumerable cements present with different properties, one should know all the properties to use it in order to give a successful restoration to the patient
  43. 43. References  PHILLIPS , SCIENCE OF DENTAL MATERIALS  11TH EDITION  CRAIG’ S RESTORAIVE DENTAL MATERIALS  12TH EDITION  STURDEVANTS ART AND SCIENCE OF OPERATIVE DENTISTRY  5TH EDITION  DENTAL CLINICS OF NORTH AMERICA  JULY 2007 51:3 SAUNDERS  DENTAL CLINICS OF NORTH AMERICA  OCTOBER 1983 27:4 SAUNDERS
  44. 44. THANK YOU

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