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  1. 1. Insulating and base materials OR Intermediary bases ( pulp protecting agents )
  2. 2. • No doubt that, dentino-pulpal organ subject to a variety of irritants with different degree due to dental caries itself, restorative procedures and from restorative material being used as fillings to restore carious lesions.
  3. 3. • So, pulp tissues must be protected from any further irritating factor or insult whether it is chemical , microbial or thermal or electrical , or the pulp may be not heal and recovery
  4. 4. • So dentist is responsible for protection of pulp through insulating base material which provide protection against thermal shock , electrical and galvanic shock ,and chemical ingredients which liberated from restorations as well as ovoid ingress and passage of the oral fluids , bacteria and debris inter- facially.
  5. 5. Insulating base materials must fulfill some important requirements which are:
  6. 6. • It must be act as impermeable membrane . • Biologically compatible with D-P organ . • Chemically compatible with restorative filling materials and dentino-pulpal organ . Requirements of insulating base materials……..
  7. 7. •Material should withstand forces of condensation of filling without deformation.
  8. 8. • Should be reduce or stabilize dentin permeability to protect the D-P organ against the toxic ionic exchange after application of filling material. • It have capability to enhance the formation of reparative dentin
  9. 9. • It should be able to produce and maintain a perfect cavity seal to avoid ingress of fluids ,bacteria and debris . • It should have thermal insulating capacity .
  10. 10. • It should have chemical insulating capacity . • It should have electrical and galvanic insulating capacity .
  11. 11. • Have a sedative and antiseptic action • From the esthetic view , did not mask or change the color or translucency of the tooth or permanent restorations.
  12. 12. Classification of intermediary bases ( pulp protecting agents) Sub-bases Film-Forming Resinous Materials: Bases:
  13. 13. • Typical cavity varnish is a natural gum or resins such as copal, rosin, or synthetic resin dissolved in an organic solvent such as acetone, ether, chloroform, alcohol . • applied in a thin film 5 - 10 micr. • and in several applications to insure minimal voids and porosities. specifications Write short notes about varnishes…………………..
  14. 14. • It can be applied to both the enamel and dentin walls of the cavity preparation. Specifications
  15. 15. Varnish applications Like nail polish
  16. 16. • Varnish produce a positive reduction of pulpal irritation through reduce infiltration of irritating fluids and ions through marginal areas of the restoration • Also, varnish can be prevent penetration of corrosion products of amalgam if it is resistant.
  17. 17. • Cavity varnish never be used under resin composite and before application of bonding system because solvent present in varnish may soften resin and discolored the material and on, prevent proper adhesion of bonding agent and the composite resin material to cavity walls and margins .
  18. 18. • A varnish never indicated when glass ionomer filling is used , the varnish coating will prevent the chemical adhesion between filling and tooth structures enamel and dentin.
  19. 19. Liners and sub-bases • Much thicker than varnish. • They are usually applied to dentin only.
  21. 21. • Are therapeutic materials placed in deep portions OF cavity preparation. • has specific pharmacological actions.
  22. 22. • sub-bases should covered with a supporting base.
  23. 23. SUB-BASE
  24. 24. Bases: • Are insulating materials that can used directly on certain areas of dentinal parts of the preparation. • Also be used indirectly as supporting, retaining modes for sub-bases.
  25. 25. BASE
  26. 26. • Varnishes • Zinc oxide and eugenol (ZOE) • Calcium hydroxide (CAOH) • Glass ionomer cement or (ASPA) • Zinc phosphate cement (ZPC) • Polycarboxylate cement (PCC) Materials Used for Intermediary Bases Enumerate different types of insulating base materials…………………………………………
  27. 27. • Calcium hydroxide : can be used as powder condition • in the form of pastes with distilled water or sterile saline . • used as a suspension in distilled water or chloroform or methyl-cellulose . Characters of CAOH as liner and sub-base material……………………………………..
  28. 28. • Calcium hydroxide cement can be supplied as two-paste system. One paste is contain calcium hydroxide + monomer of methyl-cellulose +chemical initiator and other paste contain calcium hydroxide + catalyst. • calcium hydroxide here is not inter in chemical reaction but carried by polymeric meshwork which formed.
  29. 29. • This type can be activated by laser or halogen light, called light -cured one.
  30. 30. • There is calcium hydroxide cement in which calcium hydroxide itself inter a chemical reaction with other ingredients and called acid -base reaction cement .
  31. 31. • Supplied in two separate paste, one acidic paste, formed of a compound salicylate + inert fillers ( titanium oxide and/or barium sulfate) for radiopacity, and the other paste is basic paste formed of calcium hydroxide .
  32. 32. • It is alkaline in nature. • has anti-inflammatory, antiseptic actions . • Also have a bioactive power for stimulation of odontoblasts and undifferentiated reserve cells to deposit reparative dentin.
  33. 33. • Calcium hydroxide cement mass exclusively used for a therapeutic action in the form of a sub-base in deep cavities (or as liner).
  34. 34. Zinc oxide eugenol cement Characters of Zinc oxide eugenol cement……………….
  35. 35. • Supplied as powder and liquid or a ready made paste or two paste system . The principle components of cement are zinc oxide and eugenol oil (oil of clove may replace eugenol oil)
  36. 36. Examples of modifiers used with ZOE: 1. Rosin used to improve strength, homogeneity, and smoothness of mix while decreasing flow, brittleness and solubility. 2. Ethoxy Benzoic Acid Increases strength of material, but also increases solubility.
  37. 37. 3.Fillers physically imbedded within the mass, substantially improve mechanical properties of material. Multiple fillers can be used. Examples of Polystyrene, Silica, Alumina, Diatomaceous earth, Cotton Fibers.
  38. 38. 4. Medicaments Including coagulants, and bactericidal and bacteriostatic agents, may be incorporated .
  39. 39. • It is used in operative dentistry •as temporary luting agent, •as temporary and inter- mediate restorations, •as a liner under certain filling material except resin material due to bad effect of eugenol. specifications
  40. 40. • Also ,can be used as root canal sealer •and periodontal dressings. •The reinforced cement may be used as a cement base under amalgam . specifications
  41. 41. • The pH is approximately 7-8 at the time they inserted in the cavity and considered one of the least irritating cement material and provide an excellent seal of the cavity against micro-leakage of bacteria , fluids and debris . specifications
  42. 42. • It has anti-inflammatory, antiseptic, sedative actions and a palliative and obtundent response • It has an effective thermal insulating capacity. specifications
  43. 43. • In case of deep carious lesions , it is prefer to leave the last layer of carious dentin and then sealed the cavity by temporary ZOE cement for a time ( REST TREATMENT). •Why ? specifications
  44. 44. We have four types according to the formulations : •Type I &II which are used as temporary and inter-mediate luting agents , •Type III which used as temporary restoration •and Type IV which used as cavity liner . specifications
  45. 45. this material take it's name from the formulation of glass powder and ionomeric acid (polyacrylic acid) that contain a carboxyl groups which essential for the chemical union with tooth structures enamel and dentin specifications
  46. 46. • used as esthetic restorative material •as luting agents • as a liner under composite resin (sandwich technique ) . specifications
  47. 47. • as pit and fissure sealant material as preventive agent to caries • as root canal sealer •and as core material buildups . specifications
  48. 48. So, according to the formulation of the cement we have three types, •Type I as a luting agent , •Type II as a filling material and •Type III as a liner or base material specifications
  49. 49. • It is composed of powder and liquid • or powder and water (acid is freezing and added to powder in one bottle) . specifications
  50. 50. • The powder is acid-soluble calcium alumino-fluoro-silicate glass . Barium , strontium or particles of zinc oxide is added to provide radio-opacity • liquid is composed of aqueous solution of poly-acrylic acid with other acids of maleic, itaconic and tartaric acids for decrease viscosity and tendency for gellation of poly-acrylic acid . specifications
  51. 51. • When powder and liquid are mixed, surface of powder particles attacked by poly-acid Initiation the formation of silica gel incorporated powder particles . • Calcium , aluminum , sodium and fluorine ions are leached into aqueous medium (dispersed phase) • calcium ions begin to cross linked chain of poly-acrylic acid and form a solid mass (gellation phase) . Chemistry of setting :
  52. 52. • Within first 24 hours, aluminum ions interfere within reaction with poly-acrylic acid and bonded to cement matrix and lead to more rigid and set cement . • Sodium and fluoride ions not interfere within reaction But present in form of free ions or in form of sodium fluoride dispersed within set cement . Chemistry of setting :
  53. 53. • Some specifications of GI cement e.g., reasonably bio-compatible to pulp tissues, but it is better to put a layer of calcium hydroxide liner before in case of deep cavities, • chemically bond to the tooth structures • have anti-cariogenic effect due to the presence of fluoride salts • and it has an insulating capacity.
  54. 54. Dental cement bases
  55. 55. Zinc phosphate cement zinc poly-carboxylate cement Glass ionomer cement
  56. 56. • ZPC is supplied in form of a powder and a liquid. powder is almost 90% zinc oxide, with magnesium oxide and traces of tribismuth oxide and silicone dioxide. • The reactivity of powder is controlled by temperature, time, and by particle size and shape. ZPC (Zinc Phosphate cement):
  57. 57. • The liquid is a 33% aqueous solution of orthophosphoric acid.
  58. 58. • setting reaction, mainly between zinc oxide and phosphoric acid, is an ordinary acid-base reaction. The mass has very poor packing characteristics and is extremely porous. The material is used only as a base or as a luting agent.
  59. 59. • PCC is supplied in form of a powder and a liquid. The powder is primarily zinc oxide, with small amounts (10%) of magnesium oxide and traces of alumina. • The liquid is an aqueous (40-50%) solution of polyacrylic acid. PCC (Polycarboxylate Cements):
  60. 60. • Sodium fluorides are added to some cements. They do not enter the setting reaction, but they can be released to surrounding tooth structure.
  61. 61. •As we can predict, the matrix structure is amorphous and porous to some extent, but it has better packing characteristics than ZPC. • The material is used only as a base or as a luting agent.