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GIC

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DENTISTRY

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GIC

  1. 1. GLASS IONOMER CEMENTS
  2. 2. CONTENTS  INTRODUCTION  DEFINITION  HISTORY  CLASSIFICATIONS  COMPOSITION  SETTING REACTION  PROPERTIES  CLINICAL PROCEDURES  INDICATIONS and CONTRAINDICATIONS  RECENT ADVANCES  CONCLUSION
  3. 3. INTRODUCTION • Since its extensiveusageto replacethe dentin ,hasgiven different names Dentin substitute Man made dentin Artificial dentin
  4. 4. Glass ionomer cements are tooth- colored materials that bond chemically to dental hard tissues and release fluoride for a relatively long period. They have therefore been suggested as the materials of choice for the restoration of carious primary teeth.
  5. 5.  DEFINITION of cement: - A cement is a substance that hardens to act as a base , liner , filling material or adhesive to bind devices or prosthesis to the tooth structure or to each other. - philips’ science of dental materials (12th ed)  GIC: - Water based material that hardens following an acid base reaction between basic fluoroaluminosilicate glass and an aqueous solution of polyacids. (Anusavice)
  6. 6. HISTORICAL BACKGROUND  The search for improved materials initiated numeroussearch for improved materials initiated numerous developments, such that by the 1920s three main, such that by the 1920s three main categories of cements had become established: zinccategories of cements had become established: zinc phosphate cements, zinc oxide eugenol cements, andphosphate cements, zinc oxide eugenol cements, and silicate cements.silicate cements.  In 1966, D.C. Smith introduced yet another class of cement, in which the liquid of the zinc phosphate cement was replaced by aqueous polyacrylic acid. This so-called carboxylate cement opened up new prospects for self- adhesive dental materials.
  7. 7.  On the basis of these developments, Wilson et al. introduced glass ionomer cementing materials in 1969, a material class which remains very successful today.  The first glass ionomer cement product, ASPA (Alumino-Silicate-Poly-Acrylate), introduced in the 1970s, was formulated by adding polyacrylic acid as the liquid component to finely ground silicate pow
  8. 8.  Invention of glass ionomer cement in 1969 Wilson & Kent.  Term to glass ionomer cement was coined by B.E Kent.  1972 Wilson & Crisp found that tartaric acid improves manipulative properties  1974 Mc. Lean & Wilson proposed clinical use of GIC.
  9. 9. CLASSIFICATIONS  Philips  Type I - Luting  Type II - Restorative  Type III - Liner & base  Davidson / Mjor  Conventional / Traditional GIC  Resin Modified GIC  Polyacid Modified Resin Composites
  10. 10. MOUNT: A) Glass Ionomer Cements (i) Glass Polyalkeonates (ii) Glass Polyphosphates B) Resin modified GIC C) Polyacid modified composite resin D)  Auto Cure  Dual Cure  Triple Cure E)  Type I  Type II - Type II 1 (AESTHETIC) - Type II 2 (RESTORATIVE)  Type III
  11. 11. Sturdvent 1.Conventional or Traditional 2. Metal Modified GIC - Miracle Mix - Cermet 3. Light Cured GIC 4. Hybrid (resin modified) GIC 5. Polyacid Modified Resin Composites Mc Lean and Nicholson  Glass ionomer cements  Poly alkeonates  Poly phosphonates  Resin modified GIC  Poly acid modified GIC
  12. 12.  According to clinical use as: Type I- Luting TYPE II- Restorative Type III- Liner/ Base Type IV- Pit & Fissure Sealant Type V- Luting for Orthodontic Purpose Type VI- Core build up material Type VII- High fluoride releasing command set Type VIII- ART Type IX- Geriatric & Paediatric GIC
  13. 13. COMPOSITION POWDER (Calcium Fluroaluminosilicate)  ALUMINA (28.6%) Alumina: Silica --> 1:2  SILICA (41.9%)  FLUORIDE  CALCIUM FLUORIDE (15.7%)  ALUMINIUM PHOSPHATE (3.8%)  CRYOLITE  Na+ , K+ , Ca2+  La2O3, SrO
  14. 14. Liquid: Originally was 40 to 50% aqueous solution of polyacrylic acid. Current cements the acid is in the form of copolymer with Maleic, Increase the reactivity of liquid Itaconic, Decrease the viscosity Tricarboxylic Reduce the tendency for gelatin Tartaric acid improves the handling characteristics & increase working time, but shortens the setting time.
  15. 15. FUNCTIONS OF COMPONENTS : POWDER Alumina :  It forms the skeletal structure of the glass. It also increases the opacity of the glass.  Silica :  It forms the skeletal structure of the glass and increases the transparency of the glass  Aluminium Fluoride :  It partially replaces silicon in the glass network providing negative sites, which are vulnerable to acid attack by H+ leading to decomposition of glass and providing cement potential.
  16. 16.  Fluoride :  It contributes to therapeutic value by releasing fluoride over a prolonged period of time. It helps to lower the fusion temperature. It enhances translucency and improves the working characteristics. It also helps to increase the strength of set cement  Calcium Fluoride :  It acts as a flux and provides opacity to the set cement  Phosphate :  It lowers the melting temperature and modifies the setting characteristics of the cement.  Lanthanum, Strontium, Barium :  It provides radio - opacity to the cement  Aluminum phosphate :  It helps to add body to cement and improve the translucency of the cement
  17. 17. LIQUID  The liquid is an aqueous solution of polymers and copolymers of acrylic acid.  A copolymer is a chain consisting of two molecules.  polyacrylic acid, is the most important acid contributing to formation of the cement matrix .
  18. 18. Itaconic acid  Itaconic acid promotes reactivity between the glass and the liquid.  It also prevents gelation of the liquid which can result from hydrogen bonding between two polyacrylic acid chains
  19. 19. Polymaleic acid  a stronger acid than polyacrylic acid  causes the cement to harden and lose its moisture sensitivity faster.  more carboxyl (COOH) groups which lead to more rapid polycarboxylate crosslinking
  20. 20. Tartaric acid  a reaction controlling additive .  it extends the working time.  promotes a snap set.  Strengthens and hardens the cement.
  21. 21. • Water- • It is reaction medium. • It serves to hydrate the siliceous hydrogel and the metal salts formed. • It is essential part of the cement structure. If water is lost from the cement by desiccation while it is setting, the cement- forming reactions will stop.
  22. 22. Mixing of the cement Full spoon, no excess Tip liquid bottle to side, then invert completely If water / tartaric acid, only 1 drop used.
  23. 23. Liquid should not stay on paper pad longer than 1minute (some of it may soak into it) Don’t mix beyond 30 seconds The objective is – only wet the particle – no dissolving it. First half folded into liquid in 10-15seconds Second half incorporated in 15 seconds Small mixing area Mixing
  24. 24. Manipulation consideration for GIC:  To achieve long lasting restoration and retentive fixed prostheses, the following condition for GIC must be satisfied:  The surface of prepared tooth must be clean and dry  Consistency of mixed cement must allow complete coating of surface irregularities and complete sealing of prostheses.  Excess cement must be removed at appropriate time.  Surface must be finished without excessive drying  Protection of restoration be ensured.  These conditions are similar for luting applications except that no surface finishing is needed.
  25. 25.  The powder and liquid should not be dispersed on slab until just before mixing procedure is begun; as prolonged exposure to office atmosphere alters the precise acid: water ratio of liquid.  The powder is incorporated into liquid with stiff, spatula. The mixing time should not exceed 45-60s. At this time mix should have a glossy appearance which indicates residual polyacid  Prolonged mixing leads to dull surface and adhesion will not be achieved.  GIC are also supplied in capsule containing preproportioned powder and liquid. Mixing is accomplished in an amalgamator after the seal that separates the powder and liquid is broken. Capsule also contains a nozzle for placement.
  26. 26. Working time & setting time • It sets rapidly in the mouth that is within 3-5 min and hardens to form a body having translucency that matches enamel • Setting time for type I –GIC – 5 -7 min • Setting time for type II–GIC --10 min • Film thickness should not exceed 20µm for luting agents
  27. 27. STAGES OF THE SETTING REACTION OF GLASS IONOMER CEMENTS
  28. 28.  SETTING REACTION:  The setting reaction of glass Ionomer cements involves three overlapping stages.  Stage1: Dissolution  Stage2: Precipitation of salt, gelation and hardening  Stage3: Hydration of salts.
  29. 29.  Stage1: Dissolution:  At the beginning of the reaction the surface of the glass particles is attacked by the polyacid.  This results in the dissolution of the glass particles releasing calcium and aluminium ions leading to the formination of the cement sol
  30. 30.  Stage2: Precipitation of Salts, Gelation and Hardening:  During this stage calcium and aluminum ions bind to polycarboxylate groups. The initial set is achieved by cross-linking of the more readily available calcium ions with the carboxyl of the acid.  This is the gelation phase and this reaction is relatively rapid, usually forming a clinically “hard” surface within 4-10 minutes from the start of mixing.  Maturation occurs over the next 24 hours as the less mobile aluminium ions become bound within the cement matrix, leading to more rigid cross lining between the poly (alkenoic acid) chains.  Fluoride and phosphate ions donot particpate in the crosslinking of the cement the unreacted portions of the glass particles are sheated by the silica gel which developes during the removal of the cations friom the surface of the particles.
  31. 31.  Stage 3: Hydration of Salts:  Associated with the maturation phase is a progressive hydration of the matrix salts, leading to sharp improvement in the physical properties
  32. 32.  *) Factors affecting the setting mechanism:  Glass Composition: Higher the alumima/Silica ratio, faster the set and shorter the W.T.  Powder particle size: The finer the powder, faster the set and shorter the W.T.  Addition of Tartaric acid sharpens the set without reduction in W.T.  Temperature of mix: Increase the temperature, faster the set and shorter the W.T.  Relative proportion of constituent in the mix: The greater proportion of glass and lower the proportion of H2O; faster the set and shorter the W.T
  33. 33. INDICATIONS AND CONTRAINDICATIONS:  Indications:  Restorative Materials:  Restoration of erosive/abrasive lesions without cavity preparation.  Sealing and filling of occlusal pit and fissures  Restoration of primary teeth.  Restoration of Class V carious lesions.  Restoration of Class III carious lesions, preferably using lingual approach.  Repair of defective margins in restorations  Minimal cavity preparations in approximal lesions through buccal and occlusal approach (tunnel preparations)
  34. 34. Contraindications for Use:  Class IV carious lesions (or) fractured incisors  Lesions involving large areas of labial enamel where esthetics is of major importance.  Class II carious lesion where conventional cavities are prepared, for replacement of existing amalgam restorations.  Lost cusp areas.
  35. 35. PROPERTIES  Mechanical Properties:  Strength: Glass Ionomer cements lacks sufficient strength. Improving its strength is clearly desirable and progress is being made through several approaches.  Mechanical mixing using capsules containing pre proportioned amounts of the components will statistically improve the performance of any Glass Ionomer Cement.  The strength of Glass Ionomer cement is increased as the filer content is increased and the water content is reduced.  However increased strength is accompanied by an acceleration of setting and loss of workability.
  36. 36. Compressive Strength:  Glass Ionomer compressive strength is 150-200 Mpa compressive strength is increased by increasing alumina content but this is achieved at the expense of translucency. The finer the particles the more will be the compressive strength.  Tensile Strength: Glass ionomers has a higher tensile strength when compared with silicates tensile strength 6.5 Mpa –17.4 Mpa.  Hardness:It is less than that of silicates the value is 48 KHN.  Fracture Toughness: Glass Ionomer cements are much inferior to composites in this aspect. 
  37. 37. PHYSICAL PROPERTIES:  Biocompatibility:  The biocompatibility of Glass-ionomer cements with the living tissues is a subject of importance because the glass Ionomer cements have to be in direct contact with dentin because they were designed to adhere to tooth materials by molecular bonding.  The adhesion to tooth material endures that they provide an excellent and enduring marginal seal, thus eliminating secondary caries.  Sustained release of fluoride confers resistance to caries on adjacent tooth material.
  38. 38. Fluoride Release:  The prolonged and substantial release of fluoride ions from all glass Ionomer cements is of major clinical significance.  Fluoride ions released from the restorative materials become incorporated in hydroxyapatite crystals of adjacent tooth structure to from to structure such as fluorapatite that is more resistant to acid mediated decalcification.  The fluoride originates from that used in preparing the alumino silicate glass, which can contain upto 23% fluoride.  Thickly mixed cements used for restorations release more fluoride than thinly mixed ones used for luting because they contain proportionately more glasses and hence more fluoride.
  39. 39. DURATION OF FLUORIDE RELEASE:  Large amounts of fluorides are released during the first few days after placement after which it gradually declines during the first week and stabilizes after 2-3 months and continues for a long time that is 8 years after placement and certainly longer.
  40. 40. Fluoride release
  41. 41. Sandwich techinque  The sandwich technique is developed by mclean to combine the benifical properties of gic and composite .presentely is called as bilayered or laminate techinque, it is done in large class 3 , classs 5 class4.  Clinical steps: After cavity preparation condition the cavity to develop adhension with glassinomer  Fast setting type 3glassinnomer cement is used to replace the lost dentin in sufficent bulk,  either autocured or resin modified glassinommer used.glass inomer is placed subgingivally.  Once it has set ,cut back to expose the enamel margins and allow enough bulk for composite  Etch enamel ad autocure gic for 15 sec using phosporic acid , this improes micromechinal bond to composite resins
  42. 42.  Etching is not done for resin modified gic ,when they are used etch enamel alone for 15 sec.  Wash and gentle dry  Apply enamel bonding agent ad gic base ad light cure for 20 sec processed the composite resin buildup  Advantages : flouride nfrom gic minimizes recurrent caries.  Favourable pulpal responses due to biocompatibility of gic  Better strength  excellent subgingival responses  Disadvantages: time consuming  Techinque sensitive
  43. 43. Tunnel preparation  It first described by jiks in 1963 as a conservative alternative class 2 cavity preparation in primary molars.  later hunt modifies the technique for restoring small proximal caries using glassionomercement in deciduous and permanent teeth
  44. 44. Clinical technique : Following rubber dam Isolation access is gained to the proximal caries through the occlusal aspect.  Using a no.2 round but in a high speed handplece, the preparation is started 2mm away from the marginal ridge on the involved side.  A “tunnel” is prepared diagonally under the marginal ridge into the proximal carious dentin.  Removal of the carious dentin can be done using a no.2 round bur in a slow speed hand piece.  Since access is limited loupes and caries disclosing dyes are valuable aid s in verifying whether the caries is completely removed during restoration sectional matrix band is adapted and wedge is placed cermet cement is usually used for these cavities
  45. 45. Tunnel restorations  Indications : patients with high esthetic demands and low caries rate who exhbit small proximal caries without involving marginal ridges  Contraindications: large proximal caries involving marginal ridges  Difficulty in access  Marginal ridges subjected to high occlusal loads
  46. 46. Tunnel restorations Advantages:  Conservative  Conservative preparation allos easy retention of restoration.  Less time consuming than tradition Cl II preparation  Less traumatizing to pulp  Maintenance of intact MR.  Minimal esthetic change to tooth.  Is considered not to alter interarch/Intra-arch relations.  Disadvantages:  Difficulty in complete caries removal  Collapse of MR or enamel wall may occur
  47. 47. ART Techinque  Modem restorative dentistry requirres electrically powered equipment to perform various procedures. Unfortunately, basic restorative procedures such as restoring carious lesions are not possible in developing countries especially in remote areas due to the lack of infrastructure to provide water, electricity and equipment.  In such areas, the atraumatic restorative treatment (ART) technique has proved to be a valuable method to retain as many teeth as possible under these adverse circumstances.  The ART technique was first evaluated in Tanzania in the mid 19805 and since then has become popular in several parts of the world.
  48. 48.  The ART technique consists of a simplified approach to caries management. Hand instruments are used to excavate the soft caries followed by restoring the cavities with the acutocure gic.  Indications : occlusal piit and fissure cavities of small to moderate sizes with adequate tooth structure to surroujnd the restoration  Physically or mentally handicapped patients
  49. 49. Clinical procedure  Teeth are isolated with cotton rolls  Undermined enamel is broken away using hand instruments such as hatchets.  Caries is excavated using spoon excavators.  A highly viscous glass ionomer cement is placed into the cavity and pressed by means of a gloved finger to fill the adjacent pits and fissure also  Occlusion is checked and excess material is removed before it hardens.  The restoration is finally coated with vasaline or petroleum jelly.  Advantages :max preserving tooth structure ,minimal intervention procedure, lowcost, minimal discomfort, gic{biocompatiability ,fluoride release}  Disadvantages: hand fatigue during instrumentationlack of proper access
  50. 50. RECENT ADVANCES IN GIC
  51. 51. HIGH VISCOSITY GIC Developed as an alternative to amalgam. Packable / condensable glass ionomer cements Composition: Powder: Ca,,Al fluorosilicate glass Liquid: PA,TA,water and benzoic acid INDICATIONS: Molar restoration of primary teeth Intermediate restoration Core build up material For A R T ADVANTAGES: Packable or condensable Improved wear resistance Easy to use Low solubility Rapid finishing possible Decrease moisture sensitivity DISADVANTAGES: Limited life Moderately polishable Not esthetic .
  52. 52. LOW VISCOSITY GIC 1. Also called as Flowable GIC 2. Low P:L ratio thus increase flow. 3. Use for lining, pit and fisure sealer, endodontic sealer and for sealing hyper sensitive cervical area. Eg fuji lining LC, Ketac – endo etc. Fuji lining LC Ketac-Endo
  53. 53. CERMET Cermet: this is formed by fusing the glass powder to the fine precious metal powders like silver or gold through sintering . MIRACLE MIX: 1 Seed & Wilson (1980) invented miracle mix 2 Spherical silver amalgam alloy+ G I C in ratio 1:7,and mixing it with GIC liqiuid Improves strength and abrasion resistance of the cement
  54. 54. Indications: Class I cavities in primary teeth Core build up material Lining of class II amalgam restorations Root caps for teeth under over dentures As a preventive restoration Contraindications: Anterior restoration In areas of high occlusal loading Advantages: Ease for placement Adhesion to tooth structure and anticariogenic potential Crown cutting can be done immediately Increased wear resistance Disadvantages: Esthetically poor Tooth discoloration Rough surface
  55. 55. Miracle mix COMMERCIAL PRODUCTS Ketac Silver
  56. 56. RESIN MODIFIED GIC Objective: To overcome low early strength and moisture sensitivity 1. Defined as hybrid cement that sets partly by acid base reaction and partly by polymerisation reaction (Mc Lean) 2. Powder – Ion leachable glass and initiators liquid – water, Poly acrylic acid, HEMA (15-25%), methacrylate monomers.
  57. 57. Advantages  Long working time due to photo curing  Improved setting characteristics  Decrease sensitivity to water (but not significantly, Journal of Conservative Dentistry, June 2005)  Increase early strength  Finishing & polishing can be done immediately  Improved tensile strength.  Better adhesion to composite restoration  Increase fluoride release.  Repairable.
  58. 58. Disadvantage  Biocompatibility is controversial  More setting shrinkage leading increase microleakage and poor marginal adaptation
  59. 59. POLYACID MODIFIED COMPOSITE RESIN  Also called as compomer  Defined as : material that contain both the essential components of GIC but in an amount insufficient to carry out acid base reaction in dark.  They are developed to combine fluoride release of GIC and durability of composite
  60. 60.  Composition: one paste system containing ion leach able glass, sodium fluoride, polyacid modified monomer but no water  Recently 2 paste or powder liquid system is introduced.  Powder:  Strontium aluminium flurosilicate glass particles, metal oxides,and intiators  Liquid:  Polymerizable methacrylate/caboxylic acidic monomers multi functional acrylate monomers and water ;
  61. 61.  Setting reaction 1. Initially light curing forms resin network around the glass 2. After 2 to 3 month there is water uptake which initiates slow acid base reaction and fluoride release.
  62. 62. Properties  Adhesion –Micromechanical, absence of water thus no self adhesion  Fluoride release minimal.  Physical properties better than conventional GIC but less than composite.  Optical properties superior to conventional GIC.
  63. 63. Indications  Pit and fissure sealant  Restoration of primary teeth  Liners and bases  Core build up material  For class III & V lesions  Cervical erosion / abrasion  Repair of defective margins in restorations  Sealing of root surfaces for over dentures  Reterograde filling material.
  64. 64. Contraindications  Class IV carious lesions  Large areas of labial surfaces  Class II cavities where conventional cavity is prepared  Lost cusp areas  Under full crown or PFM crowns.
  65. 65. Advantages  Ease of use  Easy adaptation to the tooth  Good esthetics  More working time than RM GIC
  66. 66. Commercial Products Compoglass F Principle Compoglass Flow
  67. 67. Fiber-reinforced Glass Ionomer Cements  Al and Sio2 fibers added to glass powder,polymer rigid inorganic matrix material (PRIMM)  Diameter of fiber is 2µm.  Advantages:  Increased wear resistance.  Improved handling characteristics  Increased depth of cure  Reduction of polymerization shrinkage  Improved flexure strength(50Mpa)
  68. 68. GIOMERS  True hybridization of GIC and composite  Combine fluoride release and fluoride recharge of GIC with esthetic easy polishability and strength of composite  Based on PRG technique.  Two types:  S- PRG :Reaction of entire glass  S-PRG: Reaction with glass surface
  69. 69. INDICATIONS  Class I, II, III, IV, and Class V cavities  Restoration of cervical erosion and Root caries  Laminates and core build up  Restoration of primary teeth.  Repair of fracture of porcelain and composites
  70. 70. Advantages  Increase wear resistance  Increase Radiopacity (glass filler)  Ideal shade match (improved light diffusion and fluorescence)  High and sustained fluoride release and recharge  Provide almost complete seal against bacterial microleakage  Little mechanical and chemical pulp irritation  Inhibit demineralization
  71. 71. Example BEAUTIFUL (SHOFU)
  72. 72. CONCLUSION  GIC’s have come a long ways since its modest beginning in 1969. Even though research can boast of substantial improvements, certain essential properties still seem to be wanting and further clinical trials are warranted for a majority of these developments. At this point of time, we are left wondering if GIC will ever be able to dominate tomorrow’s restorative scene or will it go into total oblivion. Who knows? Only the future will tell. Let us wish GIC all the best for the coming years.
  73. 73. References  Skinner’sSciencesof dental materials--- Ralph W. Phillips--- 9th Edition  Phillips’ Sciencesof dental materials---- 11th Edition  Restoration & Prevention of Tooth Structure--- Graham J. mount ; W R. Hume  Browning WD. Thebenefitsof glassionomer self-adhesivematerialsin restorativedentistry. Compend Contin Educ Dent 2006 May;27(5):308-14  operativedentitry----vimal k sikri

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