Intermediate restorative materials

4,906 views
4,435 views

Published on

Applied Dental Material
Second Year

Published in: Health & Medicine
0 Comments
20 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
4,906
On SlideShare
0
From Embeds
0
Number of Embeds
9
Actions
Shares
0
Downloads
0
Comments
0
Likes
20
Embeds 0
No embeds

No notes for slide

Intermediate restorative materials

  1. 1. Dental Cements
  2. 2.  (n): 1. A powder of calcium oxide, silica, and alumina used as an ingredient of mortar and concrete.  2. A binding element. A substance which makes objects adhere to each other or something serving to unite firmly.
  3. 3.     Dental cements are brittle materials. They are supplied mainly as powder & liquid. When mixed to a thin consistency , they are used to retain - indirect restorations. - orthodontic bands & brackets When mixed to a thick consistency , they are used as:- low strength bases [liner] - high strength bases - temporary filling - root canal sealer
  4. 4.  Dental cements can be classified according to the basic constituent of the powder into:  Zinc oxide based cements  Ion leachable glass based cements  Resin based cements  Others
  5. 5.     There are three types : Zinc Oxide - Eugenol Cement Zinc Phosphate Cement Zinc Polycarboxylate Cement
  6. 6. Supplied Form: - Powder & Liquid - Two pastes of contrast colors - One ready made paste  Composition :  Powder: - Zinc oxide [sintered to control its reactivity ] - Magnesium oxide - Zinc acetate [accelerator]  Liquid: - Eugenol [component of oil of cloves ; weak organic acid] - Other oil *to mask taste *to modify viscosity 
  7. 7.        Setting Reaction : It is an acid base reaction [ chelation reaction ]. Base + Acid Salt + H2O It is a surface reaction cored structure P+L Un-reacted ZnO moisture +Free Eugenol +Hydrated Zinc Eugenolate [amorphous matrix ] H20 changes ZnO into Zn(OH)2 to react with eugenol Factors accelerating the setting reaction: * Heat * Moisture .·.It sets quickly in the patient`s mouth The setting reaction is accompanied by slight expansion
  8. 8.       Manipulation: Proportioning according to use . Optimum P/L should be obtained to achieve best properties for the cement or Equal lengths of the two pastes Mixing on oil resistant paper pad or glass slab with stainless steel spatula . Add all the powder into the liquid at once or Mix the two pastes until uniform color is obtained The mix is first putty , then by further mixing a suitable consistency [thick & crumbly] is obtained S.T.~10 min. M.T.~1-1.5 min W.T. long
  9. 9.  Properties: 1.  Biological Properties: Its pH is ~7 [neutral] no chemical irritation It is sedative in deep cavity [Eugenol]  N.B.  It is highly irritant to the exposed pulp   Anti-bactreial effect [ZnO +Eugenol] Thermal insulation when used in thick layer [>0.5mm]
  10. 10. Properties: 2. Consistency & Film Thickness:   They depend on - Powder particle size - Powder/Liquid [application] - Viscosity of the mix
  11. 11. Properties : 2. Consistency & Film Thickness :  For luting application , thin film thickness [free of defects] is required [less than 25µm]  A 2-3 cm string of the mix occurs , when the flat surface of the St. St. spatula is pulled from the mix 
  12. 12. ZnO-E has a moderate film thickness 2535µm  For other applications , a thick film thickness is required [not less than 40µm]  The mix has the consistency of pie dough ; it can be rolled into a ball with fingers [nonsticky] 
  13. 13.  Properties: 3. Dimensional Changes During Setting : There is slight expansion  Excellent initial sealing ability
  14. 14.  Properties: 4. Solubility : It depends on  - Composition - P/L [ high ratio is desirable] - Handling of the mix  ZnO-E is the most soluble dental cement due to: - Leaching of free Eugenol - Hydrolysis of Zinc Eugenolate matrix
  15. 15. Properties : 5. Mechanical Properties :    They depend on - Composition - P/L [high ratio is desirable] - Handling of the mix Poor mechanical properties . - Compressive strength ~15 MPa - Tensile strength ~ 5 MPa . ·.brittle This makes the removal of excess after application & complete setting of the cement easier
  16. 16.  Modulus of elasticity ~ 5×103 Mpa  Mismatch in the elastic moduli of the base & restoration create tensile stresses at their interface causing fracture of either material .·.The conventional ZnO-E can not be used as a base under amalgam restoration
  17. 17.  Properties : 6. Retention (Bonding) : The bond strength of dental cement depends on :  - Strength of the cement - Film thickness of the cement - Surface texture of the tooth & restoration - Design of the restoration  It bonds by mechanical interlocking
  18. 18. Properties : 7. Optical Properties :  The presence of un-reacted ZnO in the set mass  Opaque cement .·.It is contraindicated to be used with translucent restoration
  19. 19.   1.  Modifications: These are performed either for powder liquid both Zinc Oxide Noneugenol Cement : The liquid is formulated with aromatic oils other than eugenol for patients sensitive to it
  20. 20. Modifications : 2. Polymer Reinforced Zinc Oxide –Eugenol Cement  Powder : - ZnO 80% - Resin 20 %  Liquid : - Eugenol - Polysterene  This is for Solubility Strength  since the polymer is of low water solubility .
  21. 21.  3.     Modifications: EBA –Alumina Reinforced Cement : Powder : - ZnO 70% - Alumina 30% Liquid : - Ethoxybenzoic acid 62% pinkish in colour - Eugenol 38% Alumina in the powder is strong inert additive The EBA in the liquid allows for the formation of stronger crystalline matrix
  22. 22. Modifications 4. Slow & Rapid Setting Cement :  The slow setting cement takes 24 hrs to set .  The fast setting cement takes only 5 min. to set .  This depends on * Nature of the powder * Its particle size * Concentration of accelerator
  23. 23.           Applications : Low strength base [liner] High strength base [modified version] Provisional restoration [ filling & cementation] Final cementation [ modified version] Root canal sealer [ slow setting version] Periodontal dressing Surgical dressing N.B. Never use ZnO-E with resin based restorations , because eugenol inhibits their polymerization strength & aesthetics of C.R.
  24. 24.  Introduction :  It is the oldest & most popular cement , because of : * Its long history of clinical success * Favorable handling properties [i.e. well defined W.T. & rapid S.T.] * Many applications  Supplied Form : Powder & Liquid
  25. 25.    Composition : Powder : - Zinc oxide [sintered to control its reactivity ] - Magnesium oxide - Other oxides * Strength & Smoothness - Fluorides [only when used for cementation in orthodontic ] Liquid : - Aqueous solution of phosphoric acid Dilution is necessary for the ionization of the acid to react with the powder - Aluminum phosphate *Buffer *Cement former
  26. 26.      Setting Reaction : It is an acid base reaction Base + Acid Salt + H2O It is a surface reaction cored structure P + L Mg Un-reacted ZnO AL +Hydrated Zinc-Alumino- Phosphate [ porous amorphous matrix ] The reaction is * exothermic * accompanied by slight shrinkage
  27. 27.  Manipulation :  Proportioning according to use Optimum P/L should be obtained to achieve best properties for the cement  Mixing is done on glass slab with ST.ST. spatula  The setting reaction is exothermic causing the ZnPH mix to set rapidly  S.T.~5-9 min. M.T.~1-1.5 min. W.T. well defined
  28. 28.   1. 2. 3. Manipulation : For heat dissipation , the following should be performed : Use cool dry glass slab , not below the dew point to avoid moisture condensation [ to keep H2O content & reaction rate constant ] Slow addition of small increments of powder to the liquid Mixing is done over large area of the glass slab until the desired consistency is obtained
  29. 29.      1. 2. 3. Manipulation : N.B. Any delay after mixing, the viscosity increases rapidly resulting in larger film thickness This will impair the proper seating of the restoration during cementation Care of the liquid To keep H2O content & reaction rate constant Keep the liquid in stoppered bottles Dispense the liquid just before mixing Discard the last third [clear or cloudy ]
  30. 30. Properties : 1. Biological Properties :  ZnPH is irritant to the pulp because of - Its initial acidic pH reaching neutrality within 48 hrs - No anti bacterial effect - Slight setting shrinkage .˙. ZnPH base should be preceded in deep cavity by - Cavity varnish - Subbase [cavity liner] - Dentin bonding agent  Thermal insulation when used in thick layer [>0.5mm]  Fluoride release in certain formulations
  31. 31.  1.   1. 2. Properties : Biological Properties : N.B. The patient may feel some pain during cementation This can be the result of: Acidic pH of the cement ; especially for too thin mix Osmotic pressure developed by the movement of fluid through the dentinal tubules This pain is only transient & should subside within few hrs
  32. 32.     pH @ 3 minutes ~ 4 pH @ 1 hour ~ 6 pH @ 48 hours ~ 7 Low remaining dentin thickness (RDT) requires pulp protection
  33. 33.  Properties : 2. Consistency & Film Thickness: They depend on - Powder particle size - Powder/Liquid [application]  - Viscosity of the mix
  34. 34. Properties : 2. Consistency & Film Thickness :  For luting application , a thin film thickness [free of defects] is required [less than 25µm]  A 2-3 cm string of the mix occurs , when the flat surface of the St St spatula is pulled from the mix  ZnPh is known as Crown & Bridge Cement , because it has the thinnest film thickness  For other applications , a thick film thickness is required [not less than 40µm]  The mix has the consistency of pie dough ; it can be rolled into a ball with fingers [nonsticky] 
  35. 35.  Properties: 3. Dimensional Changes During Setting :  There is slight shrinkage during setting
  36. 36. Properties : 4. Solubility :  It depends on     - Composition - P/L [ high ratio is desirable] - Handling of the mix ZnPH is soluble in water for the first 24 hrs after setting ~ 0.04 - 0.2% Then the solubility is much reduced The fluoride containing type shows some fluoride release decalcification around cemented orthodontic bands
  37. 37. Properties : Mechanical Properties : They depend on - Composition - P/L [high ratio is desirable] - Handling of the mix - Compressive strength ~100-150 MPa - Tensile strength ~ 3-4 MPa . ·. Brittle This makes the removal of excess after application & complete setting of the cement easier - Modulus of elasticity ~ 13×103 MPa [~to dentin] Mismatch in elastic moduli of the base & restoration create tensile stresses at their interface causing fracture of either material  .·.It can be used as a base under amalgam  5. 
  38. 38.  Properties : 6. Retention (Bonding) :  The bond strength of dental cement depends on : - Strength of the cement - Film thickness of the cement - Surface texture of the tooth & restoration - Design of the restoration  It bonds by mechanical interlocking
  39. 39. Properties : 7. Optical Properties :  The presence of un-reacted ZnO in the set mass  Opaque cement .·.It is contraindicated to be used with translucent restoration
  40. 40.  Applications :  High strength base  Provisional restoration [ filling]  Final cementation of - Metallic restorations - Ceramometallic restorations - Orthodontic bands
  41. 41.     Supplied Form : Powder & Liquid Preproportioned capsule for mechanical mixing Water settable cement The liquid is freeze dried & added to the powder This mixture will be only mixed with distilled H2O This supplied form has been developed - To achieve correct P/L , because the viscous liquid does not make independent drops thus giving inaccurate amount - To avoid thickening of the liquid
  42. 42.   Composition : Powder : -Zinc oxide [ sintered to control its reactivity ] - Magnesium oxide - Other oxides * Strength Smoothness - Fluorides [ only when used for cementation in orthodontics ]
  43. 43.  Composition :  Liquid : -Aqueous solution of polycarboxylic acid copolymer Dilution is necessary for the ionization of the acid to react with powder Copolymerization is necessary to avoid thickening of the liquid - Sodium Hydroxide *Buffer - Tartaric acid *To control S.T. by controlling the dissolution of powder surface
  44. 44.  Setting Reaction :  It is an acid base reaction Base + Acid  Salt +H2O It is a surface reaction P+L cored structure - Un-reacted ZnO +Hydrated Zinc Polycarboxylate [amorphous matrix ]  Factors affecting setting reaction * Heat
  45. 45.     Manipulation : Proportioning according to use Optimum P/L should be obtained to achieve best properties for the cement Mixing is done on glass slab with plastic spatula , because ZnPolyc. adheres to the ST. ST. spatula S.T.~7-9 min. [long] M.T.~30-60 sec. W.T. short
  46. 46.   1. 2.  1. 2. Manipulation : Extend the W.T. by Use of cool dry glass slab , not below the dew point to avoid moisture condensation [to keep both H2O content & reaction rate constant ] The powder is added to the liquid in only two halves N.B. The correct consistency of the mix is viscous , but the mix will flow under pressure The mix should be only used as long as it has glossy surface , otherwise there will be * Initial setting of the cement * No free COOH groups for adhesion
  47. 47.  Manipulation :  Care of liquid :  To keep both H2O content & reaction rate constant 1. Keep the liquid in stoppered bottles 2. Dispense the liquid just before mixing 3. Discard the last third [ clear or cloudy ]
  48. 48. Properties : 1. Biological Properties :  Its pH is acidic chemical irritation It is less irritant than ZnPh , because the following : 1. Polycarboxylic acid is weaker than phosphoric acid 2. Rapid rise to neutrality within 24 hrs 3. Large molecular size of the acid Difficult penetration inside the dentinal tubules 
  49. 49.  Properties : 1. Biological Properties : Some antibacterial effect [ZnO]   Thermal insulation when used in thick layer [>0.5mm]  Fluoride release in certain formulations
  50. 50.  Properties : 2. Consistency & Film Thickness: They depend on - Powder particle size - Powder/Liquid [application]  - Viscosity of the mix
  51. 51.  2.      Properties : Consistency & Film Thickness : For luting application , thin film thickness [free of defects] is required [less than 25µm] A 2-3 cm string of the mix occurs , when the flat surface of the plastic spatula is pulled from the mix ZnPolyc. has the highest film thickness 25-48µm .·.It is difficult to completely seat a retentive well fitting restoration For other applications , a thick film thickness is required [not less than 40µm] The mix has the consistency of pie dough ; it can be rolled into a ball with fingers [nonsticky]
  52. 52.  Properties : 3. Dimensional Changes During Setting : There is slight shrinkage during setting 
  53. 53. Properties: 4. Solubility :  It depends on    - Composition - P/L [ high ratio is desirable] - Handling of the mix ZnPolyc. is ~as soluble as ZnPh The fluoride containing type shows some fluoride release decalcification around cemented orthodontic bands
  54. 54. Properties : 5. Mechanical Properties :   They depend on - Composition - P/L [high ratio is desirable] - Handling of the mix - Compressive strength ~55-95 MPa - Tensile strength ~ 3-6 MPa .·. Brittle This makes the removal of excess after application & complete setting of the cement easier - Modulus of elasticity ~ 4×103 MPa Mismatch in elastic moduli of the base & restoration create tensile stresses causing fracture of either material
  55. 55.  6.   1. 2. Properties : Bonding : The bond strength of dental cement depends on: - Strength of the cement - Film thickness of the cement - Surface texture of the tooth & restoration - Design of the restoration It bonds by chemical bonding of COOH group to Inorganic portion in enamel & dentin Bond to enamel> Bond to dentin [ higher inorganic % in enamel ] Base metal alloys [ presence of surface oxide ]
  56. 56. Properties : 6. Bonding :  N.B.  Chemical bond of ZnPolyc>Chemical bond of G.I. due to moisture sensitivity of G.I.  ZnPolyc. does not bond chemically to gold alloy restorations It bonds by mechanical interlocking 
  57. 57. Properties : 7. Optical Properties :  The presence of un-reacted ZnO in the set mass  Opaque cement .·.It is contraindicated to be used with translucent restoration
  58. 58.  Applications :  High strength bases  Provisional restorations [ filling]  Final cementation of - Metallic restorations - Ceramometallic restorations - Pediatric stainless steel crown - Orthodontic bands
  59. 59. Non-resin Permanent luting cements Liquid Phosphoric acid Powder Zinc Phosphate Polycarboxylate (Zinc polyacrylate) Zinc Silicophosphate Polyacrylic acid Zinc oxide Glass Ionomer Fluoroaluminosilicate glass
  60. 60. Cement Base    Used to encourage recovery of the injured pulp and to protect it against further chemical or thermal insult Serves as a substitute for dentin lost due to decay or preparation Primary difference between liners and bases  THICKNESS (>0.75 mm)
  61. 61.     Calcium hydroxide (Dycal) ZOE (zinc oxide-eugenol) Glass ionomer Resin-modified glass ionomer (Vitrebond)   Light-cured glass ionomer Hybrid ionomer
  62. 62.  Materials that have been used   Zinc phosphate cement Reinforced zinc oxide-eugenol cement     IRM (Intermediate Restorative Material) Zinc polycarboxylate Glass ionomer cement Resin-modified glass ionomer cement
  63. 63.  Supplied Form : -Two pastes  Composition :  Base Paste : - Calcium Hydroxide - Filler *Strength *Radioopacity  Catalyst Paste : -Glycol Salicylate [weak acid]
  64. 64.     Setting Reaction : It is an acid base reaction [chelation reaction] Base + Acid Salt + H2O It is a surface reaction cored structure P+P - Un-reacted Calcium Hydroxide + Calcium Disalicylate [amorphous matrix] Factors affecting setting reaction : *Moisture .·.It sets quickly in the patient`s mouth
  65. 65.  Manipulation :  Equal lengths of the two pastes are dispensed on a paper pad  They are mixed with ST.ST. spatula to uniform color  The mix is applied only to the cavity floor , as it is highly soluble  S.T.~2-5min. M.T.~30 sec.
  66. 66.  Properties : 1. Biological Properties :  Its pH is alkaline un-reacted Ca(OH) 2 .·. It stimulates secondary dentin precipitation , when placed in contact to minute traumatic pulp exposure [direct pulp capping]  Antibacterial effect  Thermal insulation when used in thick layer
  67. 67. Properties : 2. Consistency & Film Thickness :  Creamy consistency Thin film thickness  3.  4.  Dimensional Changes on Setting : Not mentioned Solubility : It is highly soluble .·.It should not be left on cavity walls or margins
  68. 68.  Properties : 5. Mechanical Properties :  Low mechanical properties Compressive strength ~20 MPa Tensile strength ~1 MPa .·. Brittle Modulus of elasticity ~0.5×103 MPa 6. Bonding : 7. Optical Properties :
  69. 69.  Modification :  Light Cured Calcium Hydroxide :  It is supplied as one paste  It consists of - Ca (OH)2 - UDMA * Solubility - Photoinitiator
  70. 70.  Applications :  Cavity liner under C.R. , G.I. & ZnPh  Pulp capping material  Root canal sealer
  71. 71.   Supplied Form : - Liquid [clear ;yellowish] Composition : - Resin [natural or synthetic] dissolved in organic solvent [ alcohol ,acetone or ether ]
  72. 72.       Manipulation : It is applied by a disposable brush [to avoid contamination] to all cavity walls The solvent will evaporate leaving a thin coating of resin Use a gentle stream of air for drying Repeat the application up to three times to ensure a thin uniform coating of resin [more protective than one thick application] Tightly cap the cavity varnish bottle immediately after use to avoid evaporation of solvent
  73. 73.        Applications : It decreases marginal leakage around restorations It decreases the passage of chemicals from irritating base, cement or restoration It protects against the loss of constituents from the surface of the filling N.B. It should not be used under C.R. because it interferes with the action of the bonding agent which already seal the dentinal tubules It should not be used under G.I. because it interferes with fluoride uptake & chemical bonding

×