Glass ionomer cement report


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Glass ionomer cement report

  1. 1.  Glass ionomer cement is a tooth coloured material, introduced by Wilson & Kent in 1972.  -a.k.a glass polyalkenoate Silicate Glass Powder Polyacrylic acid GIC
  2. 2. Type I. For luting Type II. For restoration Type II.1 Restorative esthetic Type II.2 Restorative reinforced Type III. For liner & bases Type IV. Fissure & sealent Type V. As Orthodontic cement Type VI. For core build up
  3. 3. Powder: Acid soluble calcium fluroalumino silicate glass. Silica - 41.9% Alumina - 28.6% Aluminum fluoride - 1.6% Calcium fluoride - 15.7% Sodium fluoride - 9.3% Aluminum phosphate - 3.8% Fluoride portion act as ceramic flux. Strontium, barium or zinc oxide provide radio opacity.
  4. 4. Liquid: 1.Polyacrylic acid in the form co-polymer with itaconic acid & maleic acid . 2.Tartaric acid: improves handling characteristic & increase working time. 3.Water : Medium of reaction & hydrates the reaction products
  5. 5.  When the powder & liquid are mixed, surface of glass particles are attacked by acid. Then Ca, Al, sodium, & fluoride ions are leached into aqueous medium.
  6. 6.  Calcium poly salts are formed first, then followed by aluminum poly salts which cross link with poly anion chain.  Set cement consist of unreacted powder particle surrounded by silica gel in amorphous matrix of hydrated calcium & aluminum poly salts.  Calcium poly salts are responsible for initial set.  Aluminum poly salts form the dominant phase.
  7. 7.  Water plays an important role in structure of cement.  After hardening, fresh cement is extremely prone to the cracking & crazing, due to drying of loosely bound water .  Hence these cements must be protected by application of varnish.
  8. 8.  Type I 4 - 5 minutes  Type II 7 minutes
  9. 9.  Handling characteristics:  Previous versions of GIC had problems with inappropriate working and setting time. Tartaric acid inclusion resulted in: ▪ Tartaric acid reacting with calcium as it was released which extends working time to reasonable values ▪ Enhances rate of formation of aluminum polyacrylate crosslinks which speeds up setting.
  10. 10. Solubility and disintegration:  Initial solubility is high due to leaching of intermediate products.  The complete setting reaction takes place in 24 hrs, cement should be protected from saliva during this period.
  11. 11.  Adhesion:  Glass ionomer cement bonds chemically to the tooth structure.  Bonding is due to reaction occur between carboxyl group of poly acid & calcium of hydroxyl apatite.  Bonding with enamel is higher than that of dentin, due to greater inorganic content.
  12. 12.  Esthetics:  GIC is tooth coloured material & available in different shades.  Inferior to composites.  They lack translucency & rough surface texture.  Potential for discolouration & staining.
  13. 13.  Biocompatibility:  Pulpal response to glass ionomer cement is favorable.  Pulpal response is mild due to ▪ High buffering capacity of hydroxy apatite. ▪ Large molecular weight of the polyacrylic acid , which prevents entry into dentinal tubules
  14. 14.  Anticariogenic effect:  Fluoride is released from glass ionomer at the time of mixing & lies with in matrix. Fluoride can be released out without affecting the physical properties of cement.
  15. 15.  Initial release is high. But declines after 3 months. After this, fluoride release continuous for a long period.  Fluoride can also be taken up into the cement during topical fluoride treatment and released again ,thus GIC act as fluoride reservoir.
  16. 16.  Strength:  Compressive strength - 150 mpa  Tensile strength - 6.6 mpa.  Hardness - 49 KHN.
  17. 17. ADVANTAGES: ♣ ♣ ♣ ♣ ♣ Inherent adhesion to the tooth surface. Good marginal seal. Anticariogenic property. Biocompatibilty Minimal cavity preparation required. DISADVANTAGES: Low fracture resistance. Low wear resistance. Water sensitive during setting phase . ♦ Less esthetic compared to composite. ♦ ♦ ♦
  18. 18. 1. 2. 3. 4. 5. 6. 7. 8. Anterior esthetic restoration material for class III & V restorations. For luting. For core build up. For eroded area . For atraumatic restorative treatment. As an orthodontic bracket adhesive. As restoration for deciduous teeth. Used in lamination/ Sandwich technique.
  19. 19.  For luting:  Advantages: ▪ Fluoride release ▪ Low film thickness ▪ Kind to pulp ▪ Bond to tooth structure  Their use decreased after hybrid ionomers and resin cements were introduced since they are stronger
  20. 20.  As restorative material:  used in non-stress bearing areas: ▪ Root caries ▪ Occlusal lesions in primary teeth ▪ Temporary restorations ▪ Cervical cavities (abrasion and erosion lesions) ▪ Anterior class III when color matching is not an issue
  21. 21.  As liners and bases:  used to protect the pulp from: ▪ Temperature changes ▪ Chemicals from other restorative materials ▪ Acid etchants  Liners have lower powder: liquid ratio and weak.  GIC bases are used to rebuild missing tooth structure, stronger than liners and have a higher powder: liquid ratio
  22. 22.  As pits and fissure sealants:  The use of GICs as sealants have been suggested due to: ▪ Fluoride release. ▪ Adhesion to moist tooth structure  Disadvantages: ▪ Inability to fully penetrate fissures ▪ Brittleness ▪ Low wear resistance
  23. 23.  Core build up materials:  cermet GICs are usually used for this purpose. They are used: ▪ In locations were esthetics are not important ▪ To replace missing tooth structure where the permanent restoration is crown.
  24. 24.  Devolped by Mclean,  To combine the beneficial properties of GIC & composite.
  25. 25.    An effective technique for both anterior and posterior resin based restorations. For pulpal protection from the acid-etch technique. And as a mechanism for sealing the cavity in the absence of good dentin adhesion available with the materials of the time.
  26. 26.  Clinical steps:  After cavity preparation, condition the cavity to develop good adhesion with GIC.  Place Type III GIC into prepared cavity.  After setting, etch the enamel & GIC with orthophosphoric acid for 15 seconds. This will improve micromechanical bond to composite resin.  Apply a thin layer of low viscosity enamel bonding agent & finally place the composite resin over GIC & light cure it.
  27. 27.  Advantages:  Polymerisation shrinkage is less,due to reduced bulk of composite.  Favorable pulpal response.  Chemical bond to the tooth and composite increasing retention form.  Provides better seal when used at nonenamel margins.
  28. 28.  Advantages:  Anticariogenic property  Potential for recurrent caries low.  Decreased microleakage and gap formation.  Better strength, finishing, esthetics of overlying composite resin.
  29. 29.  Advantages for the flowable composite: (as a liner under a composite)  Acts as a shock absorber, distributing stresses applied to the more rigid composite.  Reduce some of the negative effects of polymerization shrinkage.
  30. 30. TWO TECHNIQUES: 1. Closed Technique - The traditional technique. -Involves the placement of GIC at the base of the proximal box so as it falls just short of the external cavo surface. After setting, the GIC is etched with phosphoric acid and dentin bonding agent is applied before placing composite resin into the proximal box and occlusal surface. 
  31. 31. 2. Open Technique - Involves the placement of GIC into the base of a proximal cavity and filling the preparation with glass ionomer upto the DEJ. The last portion of the restoration is placed with composite resin to provide wear resistance and esthetics on the occlusal surface. - For clinical situations where a portion of the restoration would have a dentin only margin (as in a deep class II or a class V on a root surface).
  32. 32. - Advantage of Open Technique: a. The large area of GIC available for buffering any changes in acidic pH. -Disadvantage of Open Technique: b. Over time the GIC succumbs to acid breakdown over the surface resulting in food packing and recurrent caries within glass ionomer.
  33. 33.  Factors necessary for successful tooth restoration:  Removal of infected dentin and enamel completely  Treating the enamel and dentin appropriately with bonding materials.  Manipulating properly the to-be-bonded restorative material.  Contouring the restoration to provide proper form and function.
  34. 34.  Advantages:  Polymerisation shrinkage is less,due to reduced bulk     of composite. Favorable pulpal response. Chemical bond to the tooth. Anticariogenic property Better strength, finishing, esthetics of overlying composite resin.
  35. 35. 1. Water settable glass ionomer cement:  Liquid is delivered in a freeze dried form, which is incorporated into the powder.  Liquid used is clean water.
  36. 36.  Advantages:  low viscosity in the early mixing stages  improved shelf  Improved strength
  37. 37. 2. Resin modified glass ionomer cement:  Resin composite + conventional GIC  Powder component consist of ion leachable fluroalumino silicate glass particles & initator for light curing.  Liquid component consist of water & poly acrylic acid with methacrylate & hydroxyl ethyl methacrylate monomer.
  38. 38.  Advantages:  greater working time  command set on application of visible light  good adaptation and adhesion  acceptable fluoride release  aesthetics similar to those of composites  superior strength characteristics
  39. 39.  Disadvantages:  setting shrinkage  limited depth of cure especially with more opaque lining cements.
  40. 40. 3. Metal modified glass ionomer cement:  Glass ionomer have been modified by addition of filler particles to improve strength , fracture toughness & resistance to wear. Silver alloy mix / miracle mix: This is made by mixing of spherical silver amalgam alloy powder with glass ionomer powder. Cermet:  Bonding of silver particles to glass ionomer particles by fusion through high temperature sintering.
  41. 41.  Cermets  Grey in color  Greater value of compressive strength and fatigue limit than conventional glass ionomers  Flexural strength and resistance to abrasive wear appear no better than values recorded for conventional GIC  Rapid setting  improved erosion resistance  Lower Fl release
  42. 42. 4. Giomer  It is basically a modified Glass Ionomer.  It is a hybrid of Glass Ionomer and Composite.  The GIOMER concept is based on the novel PRG (Pre-Reacted Glass Ionomer) technology, where special PRG fillers are included in the resin matrix which differs it from Compomer making it possess both properties of Composite and Glass Ionomer.
  43. 43.  PRG technology is used in production of two types of fillers.  S-PRG(Surface Pre-reacted GI) eg. Beautiful by Shofu  F-PRG(Full Pre-reacted GI) eg. Reactimer by shofu
  44. 44.  Properties         Fluoride release Esthetics (shade conformity) Ease in Polishing Strength (resistance to wear) High radiopacity Anti-Plaque Effect Biocompatibility Long term clinical stability
  45. 45.  Composition  Bisphenol A Glycidyl Dimethacrylate  TEGDMA  Inorganic Glass Filler  Aluminuoxide  Silica  PRG filler  DL-camphorquinone
  46. 46.  Indications  Diastema Closure  Discoloration  Non-Carious Defect(attrition/ abrasion/ surface     defects Carious Defect Fracture Malformation Faulty and Old Restoration
  47. 47.  Compomer  These are recently introduced products marketed as a new class of dental materials.  These materials are said to provide the combined benefits of composites (the “comp” in their name) and glass ionomers (“omer”).
  48. 48.  These materials have two main constituents:  dimethacrylate monomer(s) with two carboxylic groups present in their structure and  filler that is similar to the ion-leachable glass present in GICs.
  49. 49.  The ratio of carboxylic groups to backbone carbon atoms is approximately 1:8.  There is no water in the composition of these materials, and the ion-leachable glass is partially silanized to ensure some bonding with the matrix. These materials set via a free radical polymerization reaction, do not have the ability to bond to hard tooth tissues, and have significantly lower levels of fluoride release than GICs.
  50. 50.  Although low, the level of fluoride release has been reported to last at least 300 days.  They do not set via an acid-base reaction and do not bond to hard-tooth tissues, they cannot and should not be classified with GICs.
  51. 51. Properties          Fluoride release, Radiopaque, Quick cure time and Good handling characteristics (no slumping, easy to shape/polish, no sticking) Can be light-cure or self-cure Packaging can be unit dose (capsule) or multi-dose (syringe) Curing time: 10-20 secs (depending on brand) Esthetics
  52. 52.  Indications  Deciduous teeth  Cervical defects
  53. 53.  Disadvantages  Lower flexural modulus of elasticity,  Compressive strength,  Flexural strength,  Fracture toughness and hardness,  Higher wear rates
  54. 54.  Davidson, C. (2009) Advances in glass-ionomer cements. Journal of Minimum Intervention Dentistry.  Forsten L. Fluoride release of glass ionomers. J Esthet Dent 1994; 6:21622.  Forsten L. Resin-modified glass ionomer cements: fluoride release and uptake. Acta Odontol Scand 1995; 53:222-5.  McCabe, J. and Walls, A. Applied Dental Materials 9th edition Chap.24 pp.245-256  Millar BJ, Abiden F, Nicholson JW. In vitro caries inhibition by polyacidmodified composite resins (‘compomers’). J Dent 1998; 26:133-6.  Nagaraja Upadhya P and Kishore G. (2005) Glass Ionomer Cement – The Different Generations. Trends Biomater. Artif. Organs, Vol 18 (2)