GIC material aspect


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GIC material aspect

  1. 1. GLASS IONOMER CEMENT MATERIAL ASPECT SAGAR HIWALE 1st yr PG Dept. of conservative dentistry & endodontcs JAIPUR DENTAL COLLEGE
  3. 3. Definition Glass-ionomer is the generic name of a group of materials that use silicate glass powder and aqueous solution of polyacrylic acid” -Kenneth J Anusavice.
  4. 4. History •1965 –A.D Wilson mixed dental silicate glass powder & aqueous solutions of various organic acids including poly acrylic acid Set cement is sluggish Not reported or published. • The invention of glass ionomer cement was done in 1969.first reported by Wilson and Kent in 1971.( ASPA I) • First practical material: ASPA II in1972 by Crisp and Wilson,added tartaric acid. • ASPA III- Methyl alcohol was added. • First marketable material, ASPA IV in 1973 • Luting agent ASPA IVa in 1975 by Crisp and Abel
  5. 5. •Metal reinforced cements in 1977 by Sced and Wilson • Cermet ionomer cements in 1978 by Mc Lean and Glasser • Improved traslucency, ASPA X by Crisp, Abel,Wilson in 1979 • Water activated cements, ASPA V in 1982 by Prosser et al.
  6. 6. synonyms • Glass ionomer-term coined by wilson & kent glass-alumino silicate glass particles ionomer-poly carboxylic acid. • ISO terminology- poly alkenoate cement. • Since its co-efficient of thermal expansion similar to dentin and its extensive usage to replace the dentin ,has given different names Dentin substitute Man made dentin Artificial dentin •Introduced into u.s as ASPA-Alumino silicate polyacrylate
  7. 7. Composition • The glass ionomer powder is an acid soluble calcium fluoroaluminosiicate glass- ion leachable glass. • Composition of two commercial glasss ionomers Compound Composition A(wt%) Composition B(wt%) SiO2 41.9 35.2 Al2O3 28.6 20.1 AlF3 1.6 2.4 CaF2 15.6 20.1 NaF 9.3 3.6 AlPO4 3.8 12.8
  8. 8. • The raw materials are fused to a uniform glass by heating them to a temp.of 1100 °C- 1500°C. • Lanthanum,strontium,barium or zinc oxide additions provide radio opacity. • The glass is ground into a powder having particles in the range of 15- 50 µm. •ROLE OF COMPONENTS IN POWDER •The role of Al2O3 & SiO2 of the glass is crucial and is required to be of 1:2 or more by mass for cement formation. •CaF2-Supplemented by the addition of cryolite (Na3AIF6). •This flux -reduces the temperature at which the glass will fuse -increases the translucency of the set cement.
  9. 9. • Fluoride is an essential constituent which - Lowers fusion temp., acts as flux - improves working characteristics & strength - improves translucency - improves therapeutic value of the cement by releasing fluoride over a prolonged period • Al3PO4-Improves translucency. Apparently adds body to the cement paste
  10. 10. •LIQUID •Polyacrylic acid --- 45 % •Water --- 50 % •Modifiers Iticonic acid --- 05 % maleic acid tricarballylic acid viscosity ,inhibits gelation , shelf life. •Tartaric acid --- Working Time & setting time.
  11. 11. • The liquid is an aqueous solution of polymers andcopolymers of acrylic acid. • In most of the current cements,the acid in the form of a coploymer with itaconic ,maleic ,or tricarboxylic acids. • polyacrylic acid-is the most important acid contributing to formation of the cement matrix. • 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.
  12. 12. •Glass ionomer cements are water-based materials •Plays a role in transporting calcium and aluminium ions to react with poly acids. •Types: - Lossely bound water -Tightly bound water •With the aging of cement, the ratio of tightly bound to loosely bound water increases •Accompanied by an increase in strength, modulus of elasticity and decrease in plasticity •Cement is only stable in an atmosphere of 80% relative humidity
  13. 13. • In higher humidities the cement absorbs water and the consequent hygroscopic expansion can exceed the setting shrinkage. • Cement can lose water under drying conditions, however leading to shrinking and crazing. • Susceptibility to desiccation decreases as the cement ages • This is prevented if protected for about 10 to 30 mins (depends on manufacturer). • 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
  14. 14. • 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 Maleic acid
  15. 15. • Tartaric acid • The 5% optically active dextro-isomer of tataric acid is incorporated. • It is also hardener that controls the PH of the set cement during setting process, which in turn controls the rate of dissolution of the glass. • It facilitates extraction of ions from the glass. • It typically increases the working time and also aids in snap test.
  16. 16. CLASSIFICATION A.ACCORDING TO A.D. WILSON AND J.W.McLEAN IN 1988 Type I --- luting cements Type II --- restorative cements a.Restorative aesthetic b.Restorative reinforced B. ACCORDING TO SKINNERS Type I – Luting Type II- Restorative Type III- Liner and base
  17. 17. C. ACC.TO CHARACTERISTICS SPECIFIED BY MANUFACTURER • Type I --- Luting cement eg. Fuji I, KETAC • Type II --- Restorative material eg. Ketacfil, Fuji II, fuji IX • Type III --- a. Bases & liners • Type IV --- Admixture --- eg. Ketac silver, miracle mix D. ACCORDING TO J.W.McLEAN et al IN 1994 - Glass ionomer cement (traditional) -Resin modified glass ionomer cement -Poly acid modified composite resins
  18. 18. E. ACCORDING TO INTENDED APPLICATIONS • Type I – Luting • Type II – Restorative • Type III – Liner/base • Type IV – Pit & fissure sealant • Type V – Luting for orthodontic purpose • Type VI – Core buildup material • Type VII – High fluoride releasing command set • Type VIII – Atraumatic restorative treatment • Type IX − Pediatric Glass Ionomer cements
  19. 19. F. NEWER CLASSIFICATION • Traditional glass ionomer a. Type I --- Luting cement b. Type II --- Restorative cements c. Type III --- Liners&Bases • Metal modified Glass Ionomer a. Miracle mix b. Cermet cement • Light cure Glass Ionomer HEMA added to liquid • Hybrid Glass Ionomer/resin modified Glass Ionomer a.Composite resin in which fillers substituted with glass ionomer particles b.Precured glasses blended into composites
  20. 20. Cement placement Conditioning the Tooth Surface • Dentin conditioning prior to placement of a GIC is done primarily to remove the smear layer. •GIC is better able to wet the dentin surface. •Promotes ion exchange. •Chemically cleans dentin. •Increases surface energy.
  21. 21. Agents used Surface treatment Time of application(sec) Citric acid, 50% aq 30 Citric acid, 2% aq/alc 30 Poly (acrylic acid), 25% aq 30 Tannic acid, 25% aq 60 Surface-active solution 60 Dodicin, 0.9% aq 60 Na2EDTA, 2% aq 30 Na2EDTA, 15% aq 30 Sodium flouride, 3% aq 30 Ferric chloride, 2% aq/alc 30
  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
  24. 24. Loss of gloss/ slump test GIC --- 60 – 90 sec Resin-modified GIC --3 – 3.5 min
  25. 25. 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
  26. 26. Mixing capsules • To activate capsule apply pressure 3-4 seconds before placing in machine • Ultrahigh speed machine : 4000 cycles/minute
  27. 27. Finishing technique • Best surface –cement allowed to set under matrix •Carving the cement external to the cavity margins with sharp knives or scalers •Finest abrasive should be used to minimize tearing •Finishing with rotary instruments should be done at subsequent visit
  28. 28. Setting reaction •1. acid-base reaction •2. light activated polymerisation • ACID – BASE REACTION • GIC formed by the reaction of three materials Fluoro alumino silicate glass powder Poly acrylic acid Water • An acid – base reaction occurs between the glass powder and the ionic polymer. • Water is essential because that is the medium through which ion transfer takes place
  29. 29. • Chemistry of cement forming reaction from initial mixing occurs in various stages • The glass particles are attacked at the surface by poly acid which leads to withdrawal of the cations thus the glass network breaks down to silicic acid. • Principally Al3+, Ca2+, F-, are released and migrate into aqueous phase of cement and form complexes Decomposition of glass & migration of ions
  30. 30. • Initially calcium complexes predominate but later Aluminium complexes are more. • pH and viscosity increases • At critical pH and ionic conc. Precipitation of insoluble poly acrylates takes place. • Initial set occurs due to calcium polyacrylate but hardening of cement is due to slow formation of aluminium polyacrylate
  31. 31. • When cement is not fully hardened Al, Ca, F and polyacrylate ions may leach out leading to irretrievable loss of cement matrix • Calcium acrylate is more vulnerable to water. So the freshly set cements are to be protected. • This process continues for about 24 hrs • Undergoes slight expansion and increase in translucency • Cement becomes resistant to dessication and strength also increases for at least a year
  32. 32. •Increase in strength and rigidity are associated with slow increase in cross linking.
  33. 33. Mechanism of adhesion • Polyalkenoic acid attacks dentine and enamel: displaces PO4,Ca ions • Migrate into cement and develop an ion enriched layer firmly attached to tooth structure. • The bond strength to enamel is always higher than that to dentin because of the greater inorganic content & greater homogenity.
  34. 34. MECHANISM • Smith – chelation of calcium(1968) • Beech – interaction between apatite and poly acrylic acid polyacrylate ions Ionic bonds with calcium ions in enamel and dentin
  35. 35. • Acc. to Wilson(1974) • Initial adhesion is by hydrogen bonding from free carboxylic groups • Progressively these bonds are replaced by ionic bonds • Polymeric polar chains of acids bridge the interface between cement and substrate • Acc. to Wilson, Prosser and Powis(1983) • Polyacrylate displaces and replaces surface phosphate and calcium from hydroxyapatite • An intermediate layer of Ca and Al phosphates and polyacrylates is formed.
  36. 36. Properties of Glass Ionomer cement luting cement PROPERTY VALUES 1.Setting time(min) 7.0 2.Film thickness(µm) 24 3.24 hr compressive strength(Mpa) 86 4.24 hr diametrical tensile strength(Mpa) 6.2 5.Elastic modulus(Gpa) 7.3 6.Solubility in water(Wt%) 1.25 7.Pulp response Mild to moderate
  37. 37. Restorative cements PROPERTY GLASS IONOMER II CERMET HYBRID IONOMER 1.Compressive strength(Mpa) 150 150 105 2.Diametrcal tensile strength(Mpa) 6.6 6.7 20 3.Knoop hardness(KHN) 48 39 40 4.Pulp response mild mild mild
  38. 38. •Biocompatibility • Resistance to plaque because presence of F • Pulp response to GIC is favorable • Freshly mixed --- acidic pH 0.9 – 1.6 -- mild inflammation resolve 10 -20 days * used to protect mech / traumatic exposure of healthy pulp • Glass ionomer cement showed greater inflammatory response than ZOE but less than Zn phosphate cement & other cements but it resolved in 30 days (Garcia et al, 1981)
  39. 39. • The influence of fluoride action is seen of at least 3 mm around the glass ionomer restoration • Released for a sustained period of 18 months (Wilson et al 1985) • Thickly mixed cements release more flouride than thinly mixed ones. Fluoride release
  40. 40. Fluoride recharge • Glass ionomers may have synergistic effects when used with extrinsic fluorides • In the presence of an inverse fluoride concentration gradient, glass ionomers may absorb fluoride from the environment and release it again under specific conditions • topical APF (acidulated phosphate fluoride), with fluoride rinses and fluoridated dentifrices recharging takes place
  41. 41. • ESTHETICS • Glass ionomer cement has got a degree of translucency because of its glass filler • Unlike composite resins, glass ionomer cement will not be affected by oral fluids
  42. 42. • The esthetic quotient depends upon 1.Refractive index of glass particles and matrix 2.Particle size 3.translucency of glass particles • Specification limits of GIC 0.35 -.90 (for optimum aesthetics it is between 0.35 – 0.90 )
  43. 43. Durability Affected by the factors • Inadequate preparation of the cement • Inadequate protection of restoration • Variable conditions of mouth Failure rate is more a measure of clinician’s skill than inherent quality of the material • One of the longest observation periods for the conventional glass ionomers in non-carious cervicallesions showed retention in the order of 90% after 10 yrs for KetacFil
  44. 44. • Some other properties • Low exothermic reaction • Adheres chemically to the tooth structure • Less shrinkage than polymerizing resins • Dimensional stability at high humidity • F release discourages microbial infiltration • Early moisture sensitive --- requires protection • Poor abrasion resistance • Average esthetic
  45. 45. Indications • 1. Restorative materials: • Restoring of erosion/ abrasion lesions without cavity preparation. • Sealing and filling of occlusal pits and fissures • Restoration of deciduous teeth. • Restoration of class III lesions, preferably using a lingual approach with labial plate intact. • Repair of defective margins in restorations • Minimal cavity preparations – Approximal lesions, Buccal and Occlusal approach (tunnel preparation) • Core build-up
  46. 46. 2. Fast setting lining cement and bases: • Lining of all types of cavities where a biological seal and cariostatic action are required • replacement of carious dentin the attachment of composite resins using the acid etch technique • Sealing and filling of occlusal fissures showing early signs of caries. 3. Luting cement: • Fine grain versions of the glass ionomer Cements are used. • Useful in patients with high caries index
  47. 47. Tunnel preparation
  48. 48. Sandwich technique • Devolped by Mclean, • To combine the beneficial properties of GIC & composite. Clinical steps:-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 phosphoric acid for 15 seconds. •This will improve micromechanical bond to composite resin. •Apply a thin layer of low viscosity dentin bonding agent & finally place the composite resin over GIC & light cure it.
  49. 49. 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. • Microleakage is reduced • Minimization of no. of composite increments, therefore time is saved
  50. 50. GIC IN ENDODONTICS They are used for: • Sealing root canals orthogradely , retrogradely • Restoring pulps chamber • Perforation repair • Sometimes for repairing vertical fracture GIC was used because of : • Its capacity to bond which enhances seal & reinforce the tooth • Its good bio compatibility, which would minimize irritation to peri radicular tissues • Its F release, which imports an anti microbial effect to combat root canal infection
  51. 51. Contra indications • Class IV carious lesions or fractured incisors. • Lesions involving large areas of labial enamel where esthetics is of major importance • class II carious lesions where conventional cavities are prepared. • replacement of existing amalgam restorations. • Lost cusp areas.
  52. 52. Modifications of GIC 1.1.WaterWater settable glasssettable glass ionomer cement :-ionomer cement :- • Liquid is delivered in a freeze dried form ,which is incorporated into the powder. • Liquid used is clean water. 2.The low viscosity/flowable GIC – • For lining, pit and fissure sealing • endodontic sealers • for sealing of hypersensitive cervical areas These had a low P:L ratio and possessed increase flow. eg: Fuji lining LC, Fuji III and IV, Ketac – Endo.
  53. 53. METAL MODIFIED GIC MIRACLE MIX / SILVER ALLOY ADMIX GIC • Sced and Wilson in 1980 incorporated spherical silver amalgam alloy into Type II GIC powder in a ratio of 7:1 Powder • Glass –17.5% • Silver –82.5% Particle size of silver is 3 – 4µm Liquid • Aqueous solution of copolymer of acrylic acid and or maleic acid—37% • Tartaric acid 9%
  54. 54. Disadvantages • Resistant to burnishing • Poor aesthetics
  55. 55. GLASS CERMET • Also called as cermet ionomer cements • McLean and Gasser in 1985 first developed • Fusing the glass powder to silver particles through sintering that can be made to react with polyacid to form the cement • Sintering is done at high pressure more than 300MPa and at a temperature of 8000 C which is ground to fine powder particle size of 3.5 µm • 5%titanium dioxide is added to improve aesthetics • It has excellent handling characteristics
  56. 56. Indications • Core build –up material • Root caps of teeth under over dentures • Class I cavities. • Preventive restoration • Temporary posterior restoration Contraindications • Anterior restorations. • Areas subjected to high occlusal loading
  57. 57. PROPERTIES Strength- • Both tensile and compressive strength is greater than conventional glass ionomer cement Modulus of elasticity- • tends to be relatively lower than conventional GIC Abrasion resistance- • greater than conventional GIC due to silver particle incorporartion
  58. 58. Radiopacity: silver cermet radio opacity is equal to that of dental amalgam Fluoride release Type II cermet miracle mix • 2 weeks 440 mg 200 mg 3350mg • 1 months 650 mg 300 mg 4040 mg
  60. 60. RESIN MODIFIED GLASS IONOMER CEMENTS • developed by Antonucci, Mc Kinney and SB Mitra. • Addition of polymerizable resins to the formulation to import additional curing process to the original acid base reactions. Definition: RMGIC can be defined as a hybrid cement that sets via an acid base reaction and partly via a photo- chemical polymerization reaction. Eg:Fuji II LC, Vitrebond, Photac –Fil, Vitremer, FujiV.
  61. 61. Composition • Powder: Ion leachable glass and initiators for light / chemical / both types of curing • Liquid : water + Polyacrylic acid modified with HEMA monomers. • The HEMA content is around 15-25% and water content is low to accommodate the polymerizable ingredients. • It is a powder : liquid system with P:L = 3:1
  62. 62. Setting reaction 2 distinct setting reactions occur • Acid base neutralization • Free radicle cure. This can occur purely via light cure or by a combination of LC and chemical cure. • Thus a cement can be termed - dual cure if cross linking is via acid base + LC or - tri cure if its via acid base + Light cure + chemical cure
  63. 63. properties • Esthetics: According to the latest Skinners, there is a definite improvement in translucency as the monomer brings the refractive index of the liquid close to that of the glass particle. • Fluoride release: is same as that of the conventional but the lining version shows higher F release • Strength: The diametrical tensile strength is much higher but compressive strength and hardness is lesser.
  64. 64. • Adhesion: to tooth is reduced. This is expected because of reduction in carboxylic acid in the liquid and interruption of chemical bonding due to the resin matrix. -Adhesion to composites is increased due to the presence of residual non-polymerized functional groups within the RMGIC • Micro leakage: A higher degree of Microleakage is seen due to polymerization shrinkage • also due to reduced water and carboxylic acid content and reduces its wetting capacity
  65. 65. • Water sensitivity is considerably reduced. • The biocompatibility is controversial and precautions such as placing Ca (OH)2 in deep preparations should be taken. The transient t0 rise during setting is also a concern
  66. 66. INDICATIONS • Luting cement esp in orthodontics • Liner and base • Pit and fissure sealant • Core build up material - For amalgam repair ADVANTAGES • Long Working time and Snap setting • Early water sensitivity is reduced • Rapid development of early strength
  67. 67. • No etching is needed either to tooth for adhesion or for the material if composite lamination is to be done. • Bonding to composite is higher • Finishing can be done immediately • F release • Diametrical tensile strength is higher • DRAWBACKS • Of course some drawbacks still need to be tackled such as increased shrinkage with concurrent microleakage Low wear resistance as compared to composites Its controversial biocompatibility
  68. 68. • References  Glass ionomer cement by Alan D.Wilson and John W. Mclean  Philips science of dental materials, Eleventh edition  Sturdevant’s Art and science of operative dentistry, Fifth edition  Craig’s Restorative dental materials, Twelfth edition  G J Mount and R W Hume Text book of Minimal intervention dentistry  Advances in Glass ionomer cement , Carel L. Davidson, J Minim Interv Dent 2009; 2 (1)  Clinical evaluation of glass-ionomer Cement restorations, Martin John TYAS J Appl Oral Sci. 2006;14(sp.issue):10-3