Glass ionomer cement

glass ionomer cements ...with all recent advanves
by dr.abhijit pallewar MDS endodontics sibar dental college

1. GLASS IONOMER CEMENT DR. ABHIJIT. PALLEWAR 1 st Year MDS Dept of conservative dentistry & endodontics

2. CONTENTS INTRODUCTION HISTORY CLASSIFICATION INDICATIONS & CONTRAINDICATIONS COMPOSITION CLINICAL PROCEDURES SETTING REACTION PROPERTIES FEW APPLICATIONS OF GIC MODIFICATIONS OF GIC RECENT ADVANCES CONCLUSION

3. INTRODUCTION

4. 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 12 th edition Glass ionomer is a water based cement ADA specification number: 96

5. During the last decades, an increasing variety of dental restorative materials have conquered the market. Gold and ceramics are the main standard material used for indirect restorations, and until the late seventies amalgam was used for direct restorations. Today, the decreased number of amalgam fillings is also influenced by a high demand for tooth-colored and biocompatible restorations.

6. Great strides in dental research have led to a variety of alternatives to amalgam one of which is Glass Ionomer Cement In dentistry adhesion of restorative materials to tooth substance is an important objective. It is believed that a restorative material should resemble the tooth in all respects.

7. The glass ionomer cements are one of the products developed in this direction. Glass ionomer cement are described as a hybrid of dental silicate cements and zinc polycarboxylates . Glass ionomer cements, are materials made of calcium, strontium aluminosilicate glass powder (base) combined with a water-soluble polymer (acid).

8. DEFINITIONS

9. GIC Acquired its name from its composition of glass particles and an ionomer that contains carboxylic acid. Extensive use of this cement to replace dentin , has given it different names: 1) Dentin substitute 2) Man made dentin 3) A rtificial dentin 4) Alumino Silicate Polyacrylic Acid(ASPA)

10. HISTORY

11. Scientific development: D.C. smith in 1968 used poly acrylic acid in zinc polycarboxylate cement 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 First marketable material, ASPA IV in 1973 Luting agent ASPA IVa in 1975

12. 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.

13. Clinical development: First clinical trials in 1970 by Mc Lean Class I restorations, fissure sealing and preventive dentistry in 1974 by Mc Lean and Wilson Erosion lesions, deciduous teeth, lining, luting,composite / ionomer laminates in 1977 by J. W. Mclean & A. D. Wilson.

14. Improved clinical techniques between 1976-77 by G.J.Mount & Makinson,1978 Approximal lesions and minimal cavity preparation in 1980 by Mc Lean Water activated luting cements in 1984 by Mc Lean et al Tunnel class I and II preparations by Hunt and Knight in 1984 Double etch ionomer /composite resin laminates,1985,Mc Lean

15. COMPOSITION

16. POWDER

17. Basic component is a calcium alumino silicate containing fluoride. Glasses are prepared by fusing the components between 1100 c - 1500 c then pouring the melt onto a metal plate or into water. The glass is then ground to a fine powder, size ranging between 20µ for luting to 50µ for restoration. They get decomposed by acids due to the presence Al +3 ions which can easily enter the silica network. It is this property that enables cement formation.

18. Calcium fluoride (Ca F2) - Increase opacity - Acts as flux Aluminium phosphates - Decrease melting temp. - Increase translucency Cryolite (Na3 Al F6) - Increase translucency - Acts as flux Alumina (Al2 O3) - Increase opacity Silica (SiO2) - Increase Translucency Fluoride: Its has 5 functions - Decrease fusion temp. - Anticariogenecity - Increase translucency - Increase working time - Increase strength Glass ionomer cements in dentistry : a review International journal of plant, animal and environmental sciences 2011;1(1)

19. LIQUID water is an important constituent of GIC, It is the reaction medium and helps in hydrating the matrix. The three acids itaconic , maleic and tricarboxylic acid decrease viscosity of liquid , Promote reactivity, prevent gelation of liquid.

20. Tartaric acid - Increases WT - Increases translucency - Improves manipulability - Increases strength 5-15% of optically active isomer of TA is added. Polyphosphates: extends Working Time . Metal oxides: accelerates Setting Time. Glass ionomer cements in dentistry : a review International journal of plant, animal and environmental sciences 2011;1(1)

21. CLASSIFICATION

22. 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 .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 --weak with less acidic b . Bases & liners --stronger but more acidic c . Bases & liners --strong even in thin layer Type IV --- Admixture eg . Ketac s ilver, miracle mix

23. C. ACCORDING TO SKINNERS Type I – Luting Type II- Restorative Type III- Liner and base D. ACCORDING TO J.W.McLEAN et al IN 1994 Glass ionomer cement (traditional) Resin modified glass ionomer cement Poly acid modified composite resins  

24.   E. ACCORDING TO USES: 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

25. 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  

26. MODE OF SUPPLY Powder, liquid Pre proportioned capsules   ANHYDROUS CEMENT Anhydrous cement was introduced in order to avoid increased viscosity due to Increasing molecular weight of polyacids . In this freeze dried polyacid powder and glass powder are placed in the same bottle Liquid is water or water with tartaric acid Also called as water settable cement Facilitates mixing and extends shelf life  

27. 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 . INDICATIONS

28. Repair of defective margins in restorations Minimal cavity preparations – Approximal lesions, Buccal and Occlusal approach (tunnel preparation) Core build-up Provisional restorations where future veneer crowns are contemplated Sealing of root surfaces for overdentures .

29. Lining of all types of cavities where a biological seal and cariostatic action are required Replacement of carious dentin and the attachment of composite resins using the acid etch technique . Sealing and filling of occlusal fissures showing early signs of caries. 2 . Fast setting lining cement and bases:

30. 3. Luting cement: Fine grain versions of the glass ionomer cement are used. Useful in patients with high caries index

31. CONTRAINDICATIONS 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.

32. To ensure successful Glass Ionomer restoration following parameters are to considered:- 1.Preparation of tooth surface 2.Proportioning & mixing 3. Protection of cement during setting 4. Finishing 5.Protection of cement after setting CLINICAL PROCEDURE FOR PLACEMENT

33. 1. Select the appropriate shade of the cement. Isolate the tooth with rubber dam where there is any risk of gingival seepage or bleeding. Prepare the cavity- erosion/abrasion lesion:-clean only with pumice slurry -Carious lesion: conventional instrumentation to remove caries and provide some mechanical retention.

34. Where there is less than 0.5mm of remaining dentin , line the cavity with a fast setting Ca(OH)2 5.Apply a surface conditioner to the cavity to remove the smear layer and improve the adhesion. 6. Dispense the cement on a cooled glass slab and mix quickly (30 secs for hand mixing and 10 secs for machine mixing). Alternatively a paper pad can be used. The mix should have a glossy appearance

35. Full spoon, no excess Tip liquid bottle to side, then invert completely If water / tartaric acid, only 1 drop used. Hand dispensing

36. Hand mixing Liquid should not stay on paper pad longer than 1minute (some of it may soak into it) First half folded into liquid in 10-15seconds Second half incorporated in 15 seconds Small mixing area Don’t mix beyond 30 seconds The objective is – only wet the particle – no dissolving it.

37. Correct consistency for hand mixed Type I : Luting : string up to 3-4cm from slab Type II : string 1cm + gloss Type III : As lining for amalgam : 1.5:1 P/L ratio 3-4 cm string As a base for composite : 3:1 P/L ratio 1-1.5 cm string

38. Mixing of capsules To activate capsule apply pressure 3-4 seconds before placing in machine Ultrahigh speed machine : 4000 cycles/minute (< 3000 cycles/minute – not desirable)

39. Wash and lightly dry the cavity. The surface should be dried but not desiccated as this tends to reduce the wettability . Insert the cement using a spatula or a syringe 8. Place a preshaped matrix wherever possible. 9. Allow to set. Remove the matrix and immediately apply varnish or bonding agent .

40. 11. Trim any excess, external to the cavity with scalpel blade. 12. Reapply varnish or bonding agent. 13. The final polishing should be delayed till the next appointment or at least 24hours. 14. Reapply varnish or bonding agent after polishing .

41. - Best surface finish obtained – if 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. FINISHING OF GIC

42. SETTING REACTION

43. IT IS AN ACID BASE REACTION BETWEEN ACIDIC POLYELECTROLYTE AND BASIC GLASS POWDER.

44. STAGES OF SETTING REACTION

45. 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 I nitially calcium complexes predominate but later aluminium complexes are more. pH and viscosity increases DECOMPOSTION OF GLASS AND MIGRATION OF IONS

46. 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 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. Gelation and vulnerability to water

47. Hardening and slow maturation 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. Increase in strength and rigidity are associated with slow increase in cross linking..

48. Cored filler is bound together by a hydrogel of Ca and Al poly acrylates that contain fluorine :- FLUORO ALUMINO CALCIUM POLYACRYLATE CEMENT STRUCTURE

49. WORKING TIME AND 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   CONSISTENCY AND FILM THICKNESS : Film thickness should not exceed 20µm for luting agents It is similar to or less than zinc phosphate cement and is suitable for cementation .

50. Factors affecting setting characteristics Role of fluoride Effect of tartaric acid Factors affecting rate of setting Glass composition Particle size Addition of tartaric acid Relative proportions of constituents Temperature of mixing

51. Plays an important role in setting reacton and structure of cement. Acts as reaction medium Hydrates the siliceous microgel and metal poly acrylate salts. THE ROLE OF WATER

52. Early contamination Loss of calcium polyacrylate chains Loss of translucency Loss of physical properties Leaves cement susceptible to erosion Dehydration Cracking & fissuring of cement Softening of surface Loss of matrix-forming ions CRACK IN UNPROTECTED GIC

53. Water present in set cement can be classified in to two forms: a ) loosely bound water b) tightly bound water : Its is the water which is readily removed by desiccation . Water is easily lost and gained by the cement as the loosely bound water is labile. LOOSELY BOUND WATER

54. Its is the water which cannot be removed . Its is associated with the hydration shell of cation-polyacrylate bond. As the cement ages the degree of of hydration ↑ that is the ratio of tightly bound to loosely bound water increases which in turn increases strength and modulus of elasticity and decrease plasticity (according to wilson et al 1981). TIGHTLY BOUND WATER

55. RESIN COATING(protection of cement) Water plays a key role for proper maturation of GIC. water contamination and dehydration during the initial setting stages can compromise the physical properties of the restoration. It is recommended to strictly exclude water during the vulnerable setting stage, which is reported to last for atleast one hour until even two weeks after placement. Petroleum jelly, cocoa butter, waterproof varnishes, and even nail varnishes have been recommended as suitable surface coating agents. Coatings are lost by oral masticative wear, but by this time the cements become more resistant to variations in water balance due to their post-hardening. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

56. Among the coating strategies, light-polymerized resin coatings have been considered the optimal surface protecting agent. Hotta et al. found, that the use of light-polymerized bonding or glazing agents are able to limit water movement across the setting cement surface. Recently, a new restorative concept has been marketed ( Equia ®, GC Europe, Leuven, Belgium), a system application consisting of a posterior restorative GIC combined with a novel nanofilled coating material. This self-adhesive, nanofilled resin coating that provides a high hydrophilicity combined with an extremely low viscosity, accounts for a perfect seal of a GIC surface, as shown in Figure 6 Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

57. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

58. Linear-Elastic Mechanical Properties The compressive strength of GIC is commonly measured after 24 hours wet storage. Compressive strength ranges between 60 and 300 Mpa and flexural strength up to 50 Mpa . GIC exhibit a significant increase (approximately 100%) in flexural as well as in compressive strength when exposed to water in the period between 24 hours and one year after mixing . When exposed to aqueous solutions of varying pH, GIC exhibited a high acid erosion resistance compared to other restorative materials. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

59. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

60. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ULRICH LOHBAUER et al Materials 2010,3,76-96

61. Properties Of Restorative Gic 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.Solubility(ANSI/ ADA Test) 0.4 - - 5.Pulp response mild mild mild

62. 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 Properties Of Luting Gic

63. WEAR AND FATIGUE Deterioration is described in general terms of wear, marginal breakdown and fatigue fracture due to cyclic loading. Braem et al. proposed average human chewing stresses between 5 MPa and 20 MPa at a chewing frequency of approximately 2 Hz. The number of occlusal contacts per day at medium chewing forces was estimated to range between 300 to 700 cycles. In dentistry, the loss of material due to non-antagonistic contacts have been defined as occlusal contact free area (CFA ) wear. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

64. Occlusal contact area (OCA) wear has been designated as material loss by direct interaction of an antagonist with the restorative material. GIC exhibit a CFA wear five times higher than amalgam and three times higher than resin composite materials. Failure mechanisms such as void nucleation, crack propagation and detachment of particles or sudden, subcritical failure are common features in wear and fatigue. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

65. THERMAL COMPATIBILITY The tooth structure and restorative materials in the mouth will expand upon heating by hot foods and beverages but will contract when exposed to cold substances. Such expansions and contractions may break the marginal seal of an inlay or other fillings in the tooth, particularly if the difference in coefficient of thermal expansion (CTE) is great between the tooth and the restorative material. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

66. practically relevant temperature range between 20 °C and 60 °C, materials such as resinous composites and amalgam expand more than the tooth tissue, whereas porcelain and glass ionomer cements are well adapted to the tooth tissue.

67. ANTICARIOGENIC PROPERTIES Fluoride is the most effective agent in caries prevention. The metabolism of the bacteria that cause caries is inhibited and the resistance of enamel and dentin is increased due to the remineralization of porous or softened enamel and dentin. Sustained, long-term fluoride release especially in marginal gaps between filling material and tooth help prevent secondary caries of the dental tissues. For conventional GIC, an initial release of up to 10 ppm and a constant long-term release of 1 to 3 ppm over 100 months was reported. Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

68. 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 is restricted by sodium and to some,extent by calcium content. Water plays a critical role in the fluoride release of GIC , the aqueous phases of the set GIC exist in he form of hydrogels that allow chemical equilibrium with an ion movement between GIC and the oral cavity & surrounding tooth structures. FLUORIDE RELEASE

69. GIC is also described as ‘smart” restorative material because apart from releasing fluoride to surrounding tooth structure, they can also “recharge” themselves by fluorides. This is also referred to “reservoir effect”. From saliva there is an ion exchange of fluoride ions diffusing from GIC (area of high conc.) to the tooth (area of low fl conc.). Released fluoride is incorporated in to hydroxyapatite crystals of the enamel and dentin over an area of approx. 1-3 mm surrounding the restoration forming hydroxyfluorapatite .

70. Fluoride containing oral care products including topical fluoride gel applications , tooth pastes and mouth rinses can recharge the GIC restoration with fluoride. .

71. 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. Because of slow hydration reactions glass ionomer cements take at least 24 hrs to fully mature & develop translucency. Early contamination with water reduces translucency. AESTHETICS

72. Dark shades are less translucent . 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 - 0.90 (for optimum aesthetics it is between 0.35 – 0.90 )

73. Glass ionomers bond permanently to tooth structure and also to other polar substrates such as base metals. Barriers of adhesion 1) water 2) dynamic nature of tooth material. ADHESION

74. Mechanism Of Adhesion According To Different Authors: .

75. 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.

76. IMPROVING ADHESION Tensile bond strength to enamel- 2.6 to 9.6 MPa dentin- 1.1 to 4.5 Mpa Surface Conditioning Smoothing of surface irregularities 1) Prevent air entrapment 2) Minimizes areas of stress concentration 3) Improves bond strength esp. to dentin

77. 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

78. SEM of dentin without surface conditioning SEM of dentine after treatment with citric acid

79. Erosion is as a result of chemical attack and mechanical wear Chemical erosion is due to acids generated by dental plaque,or contained in food and beverages Acid erosion –glass ionomer < silicate < zinc phosphate < poly carboxylate Silicate cement Glass ionomer cement EROSION

80. BIOCOMPATABILITY

81. 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). Reasons for blandness (Mc Lean and Wilson, 1974) - 1.poly acrylic acid is weak acid 2.Tendency of acid to dissociate in to H+ and polyacrylate ions is reduced after partial neutralization wjich makes the acid weaker. 3.Acid is readily neutralized by Ca2+ ions in tubules. 4. Because of its higher molecular weight and chain entanglement there is unlikely of diffusion of polyacid in to dentinal tubules. Reference book :Glass Ionomer Cement :Alan D Wilson/ john w.McLean chapter 8 page no.126

82.   First described By Mc Lean & Wilson In 1977. The procedure involves :- Placing GIC as base of cavity . Etching with 37% phosphoric acid for 1 min causes surface roughness Dentin bonding agent is applied. Placing composite restoration. SANDWICH TECHNIQUE

83. Advantages included:   GIC acts as a dentin substitute The high contraction stresses produced (2.8 – 3.9 Mpa ) by the polymerization shrinkage are reduced as the amount of composite is reduced . Microleakage is reduced. Minimization of no. of composite increments, therefore time is saved. Close sandwich technique Open sandwich technique

84.   A cariostatic action is essential for caries ,preventive material GIC is recommended as a P and F sealant where the orifices of the fissure are patent . The size of the fissure should allow sharp explorer tip to enter the crevice which should be > 100 µ wide. Otherwise, GIC can get lost through erosion due to its low wear resistance and solubility. PIT AND FISSURE SEALANTS

85. The metal reinforced glass ionomer cements are used for this purpose Glass ionomer cements reinforce the teeth &prevent root fracture when root canals are over widened. CORE BUILD UP

86. TUNNEL PREPARATION First described in 1963 Conservative alternative cavity preparation in primary molars. Indication:- Small proximal caries with out involvement of marginal ridges.

87. They are used for : Root end fillngs Root canal sealer Perforation repair Intraorifice barriers Temporary coronal restorations GIC is used because of : Its capacity to bond which enhances seal & reinforce the tooth Its good biocompatibility , which would minimize irritation to peri radicular tissues Its F release ability, which imparts an antimicrobial effect to combat root canal infection.   GIC IN ENDODONTICS Clincal application of glass ionomers in endodontics : a review – zahed mohammadi at al International dental journal 2012;62:244-250

88. Developed by Antonucci , Mc Kinney and SB mitra . It was developed in between late 1980s and early 1990s . Resin modification of glass ionomer cement was designed to produce favourable physical properties similar to those of resin composites while maintaining basic features of conventional GIC. RESIN MODIFIED GIC 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

89. Powder Liquid Purpose for their inclusion Barium, strontium or aluminosilicate glass   Improved strengthImparts radiopacity Vacuum-dried polyacrylic acid Polyacrylic acid Reacts with the glass to form the poly salt matrix Potassium persulphate   Redox catalyst system to provide the methacrylate (dark) cure Ascorbic acid   Pigments   Varies shade   HEMA Water miscible resin   Polyacrylic acid with pendant methacrylates (copolymer) Ability to undergo both acid–base and polymerization reactions Helps form interpenetrating network   Tartaric acid Sharpens the acid–base reaction set   Water Permits reaction between the polyacid and the glass   Photo-initiators Achieves light curing COMPOSITION

90. Addition of polymerizable resins to the formulation is done to import additional curing process to the original acid base reactions . 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 These products are considered to be dual –cure cements if only one polymerization mechanism is used , if both mechanisms are used they are considered to be tri-cure cements.

91.   The sequence of the two setting reactions in a dual-cured resin modified glass ionomer cement. The boxes coloured in pink indicate the glass ionomer cement reaction, while those in blue indicate the resin polymerization reaction initiated by light. SETTING REACTION OF RMGIC

92. SETTING REACTION OF TRICURE RMGIC Tri-cured : acid-base reaction + light activation + dark redox .

93. PROPERTIES: Esthetics : According to the 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.

94. 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 Due to reduced water and carboxylic acid content , reduces its wetting capacity.

95. Water sensitivity is considerably reduced. The biocompatibility is controversial and precautions such as placing Ca (OH) 2 in deep preparations should be taken and the transient t rise during setting is also a concern. INDICATIONS :- Luting cement in orthodontics Liner and base Pit and fissure sealant Core build up material For amalgam repair

96. ADVANTAGES Long Working time and Snap setting Early water sensitivity is reduced Rapid development of early strength 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

97. 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.

98. MIRACLE MIX / SILVER CERMET Silver cermet was introduced by Simmons in year 1983. 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% METAL MODIFIED GIC

99. Disadvantages Poor resistance to abrasion Resistant to burnishing Poor aesthetics

100. 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 800 C which is ground to fine powder particle size of 3.5 µ 5% titanium dioxide is added as whitening agent to improve aesthetics. It has excellent handling characteristics.

101. Indications Core build –up material Root caps of teeth under over dentures class I cavities in 1 teeth Lining for class SAF Preventive restoration Temporary posterior restoration Contraindications Anterior restorations. Areas subjected to high occlusal loading

102. 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 Radiopacity : silver cermet radio opacity is equal to that of dental amalgam.

103. According to a study conducted By Sinha S.P et al they found photomicrographs of scanning electron microscope (500x) of silver amalgam showed more marginal gap than glass ionomer and cermet ionomer cements. In this study cermet glass ionomer showed the least microleakage and the best sealing ability among other retrograde filling materials.

104. RECENT ADVANCES IN GIC

105. IMPROVED TRADITIONAL GIC : - HIGHLY VISCOUS/ PACKABLE GIC - LOW VISCOSITY GIC POLYACID MODIFIED GIC /COMPOMER SELF HARDENING GIC  NEW FLUORIDE RELEASING GIC: A) FLUORIDE CHARGED GIC B) LOW PH ‘SMART’ MATERIALS

106. BIOACTIVE GLASS FIBRE-REINFORCED GIC GIOMER ZIRCONOMER HAINOMER AMALGOMER CHLORHEXIDINE IMPREGNATED GIC

107. Highly viscous/ packable / condensable GIC - alternative to amalgam in posterior preventive restoration. Fast setting Auto cure cement. 10-15% better physical properties than resin modified glass ionomer Available as “normal set” or “fast set” Particularly useful as transitional restoration Changes :powder particle size particle size distribution Heat history of glass (improvement in surface reactivity of powder) IMPROVED TRADITIONAL GIC

108. Polyacrylic acid is made to finer grain size so that higher powder liquid ratio can be used. SIGNIFICANT FACTORS P/L ratio:3:1 to 4:1 Resistance to water uptake/ loss as soon as set. Adhesion is stronger. Release of ions: similar to other types of autocure , therefore useful for root surface caries, tunnels.

109. PHYSICAL PROPERTIES: Tensile strength & fracture resistance substantially better than autocure , marginally better than resin modified glass ionomer Abrasion resistance – as they mature they match that of amalgam, composite resin Radioopacity - adequate Used in - ART procedure - Restorations for deciduous teeth. - Intermediate restoration - core build- up materials Eg . Ketac molar, Hi- Fi , Fuji VIII and IX

110. . CC bonifac et al conducted a study between six commercially available GIC and the aim of there study was to investigate the mechanical properties of GICs used for ART i.e Wear resistance, flexural and compressive strength and Knoop hardness were evaluated. They concluded that Ketac Molar Easymix and Fuji IX presented the best performance in all the tests. Physical-mechanical properties of glass ionomer cements indicated for atraumatic restorative treatment - CC Bonifac et al Australian Dental Journal 2009; 54: 233–237

111. Letícia Busanello et al conducted a study to compare & evaluate compressive strength of glass ionomer cements used for atraumatic restorative treatment. The found that among all Fuji IX presented the best results after 1 hour. Following 24-hour storage, Fuji IX, Ketac Molar, and Vitro Molar had similar performance. Except for Fuji IX, all materials presented higher compressive strength values after 24 hours than after 1 hour. Compressive strength of glass ionomer cements used for atraumatic restorative treatment - Letícia Busanello et al Rev. odonto ciênc 2009;24(3):295-298

112. ii) The low viscosity/ flowable GIC – For lining, pit and fissure sealing endodontic sealers for sealing of hypersensitive cervical areas These have a low P:L ratio and posses increase flow. eg : Fuji lining LC, Fuji III and IV, Ketac – Endo.

113. POLYACID MODIFIED GIC /COMPOMER

114. Definition : Compomer can be defined as a material that contains both the essential components of GIC but at levels insufficient to promote the acid –base curing reaction in the dark . Compomer is a combination of the word ‘comp’ for composite “ omer ” for ionomer . Though introduced as type of GIC, it became apparent that terms in of clinical use and performance it is best considered as a composite.

115. COMPOSITION Compomers are essentially a one – paste system containing ion leachable glass & polymerizable acidic monomers with functional groups of polyacrylic acid & methacrylates in 1 molecule. NaF and some other fillers are also present for additional F release and Radio opacity. There is no water in the formulation. Glass particles are partially silanated to ensure bonding.

116. SETTING REACTION Setting reaction occurs in 2 stages Stage 1 : In contrast to RMGIC, a typical composite resin network around filler particles forms on light activation . Stage II : occurs over 2-3 months when the water from the saliva gets absorbed and initiates a slow acid base reaction with formation of hydro gels within the resin and low level fluoride release.

117. PROPERTIES ADHESION : to tooth requires acid –etching because acid base reaction for ion exchange requires water which does not occur for some time after placement. Bond strengths achieved usually approach the typical resin bonding systems. It is = 18-24Mpa   FLUORIDE RELEASE : is limited. It is significantly less than Type II or RMGIC. F release usually starts after about 2-3 months; it peaks initially and then falls rapidly. PHYSICAL PROPERTIES : fracture toughness, flexural strength and wear resistance are better than GIC but less than composite.

118. The in vitro study conducted by vishnu et al found that the highest tensile bond strength for compomers and the least tensile bond strength for chemically cured glass ionomer cement. They concluded that the tensile bond strength of Compoglass ( compomer ) is significantly greater than Fuji IX GP and Fuji II LC(RMGIC) Comparative evaluation of tensile bond strength and microleakage of conventional glass ionomer cement, resin modified glass ionomer cement and compomer : An in vitro study C. Vishnu Rekha et al Contemporary Clinical Dentistry2012;3(4)

119. INDICATIONS P& F sealant Restoration of 1 teeth, class III and V lesions along with cervical abrasions and erosions and intermediate restorations. Bases for composites, liners Small core build ups Filling of pot holes & undercuts in old crown preparations Root surface sealing

120. ADVANTAGES Superior working characteristics to RMGIC Ease of use Easily adapts to the tooth Good esthetics CONTRAINDICATIONS Class IV lesions Conventional class II cavities Lost cusp areas Restorations involving large labial surface

121. Recently, a 2 component compomer is being marketed as a P: L system or 2 paste system meant exclusively for luting . These are self adhesive due to the presence of water which starts off the acid base reaction. The powder contains the glasses, fluoride & chemical / light initiators . liquid contains the monomers, Polyacrylic acid, water and activators. These set via light chemical polymer as well acid base reaction.

122. These are basically, purely chemically activated RMGIC with no light activation at all. Developed mainly for luting purposes, they contain monomers and chemical initiatiors such a the benzoyl peroxide and t- amines to allow self polymerization. It is used mainly in paediatric dentistry for cementation of stainless steel crowns, space maintainers, bands and brackets. SELF HARDENING RMGIC

123. ADVANTAGES Its advantages include: Ease of handling No post- cementation sensitivity Fluoride release Higher compressive strength No additional step of light activation

124. Hench -1969 and various studies were performed to ensure that bioactive glasses are safe for clinical applications , Wilson et al (1981) reviewed these studies & proposed that this are safe for clinical use. Bioactive glass can form intimate bioactive bonds with the bone cells and get fully integrated with the bone. Bio-active glass (BAG) can act as a source of a large amount of CaO and P2O5 in a Na2O–SiO2 matrix with a rapid dissolution rate and high ionic concentration. BIO ACTIVE GLASS

125. BAG 45S5 exhibits a high bioactivity index (IB = 12.5) compared to other bio-active materials such as hydroxyapatite (IB = 3), and therefore it has the potential to remineralise enamel white spot lesions with an increased rate of HA formation. According to study conducted by hussam et al they found that BAG exhibited a potential of remineralisation of white spot lesions to an extent and further modification has a potential to promote entire mineral gain of treated lesions. Enamel white spot lesions can remineralise using bio-active glass and polyacrylic acid-modified bio-active glass powders hussam mily et al JCD 2014;14

126. It is being used experimentally as Bone cement Air abrasive powder in MID. Retrograde filling material For perforation repair Augmentation of alveolar ridges in edentulous ridges. implant cementation Infra- bony pocket correction

127. Incorporation of alumina fibres into the glass powder to improve upon its flexural strength This technology called the Polymeric Rigid Inorganic Matrix Material or PRIMM developed by Dr. Lars Ehrnsford It involves incorporation of a continuous network / scaffold of alumina and SiO 2 ceramic fibres . FIBRE REINFORCED GIC

128. ADVANTAGES: Due to the ceramic fibers there is increased depth of cure as light conduction and penetration is enhanced. Polymerization shrinkage is reduced as resin is confined within the chambers. There is also improved wear resistance Increase in flexural strength.  

129. Developed by Shofu Recently ,a new category of hybrid aesthetic restorative material,which differs from both resin modified GICs and compomers has been introduced known as GIOMERS Giomers are available in market as one paste form and these are light polymerizing and require bonding agents for adhesion to tooth structure.. Commercially available as Reactmer ( shofu,japan ), beautifil ( shofu,japan ) & beautifil II ( shofu , japan ).

130. Chemical Nature Giomer utilizes the hybridization of GIC and composite by using a unique technology called the pre-reacted glass ionomer technology. The fluoro aluminosilicate glass is reacted with polyalkenoic acid to yield a stable phase of GIC this pre reacted glass is then mixed with the resin. Depending on the amount of glass which is reacted, the PRG technology can be 2 types: F- PRG = Full reaction type / entire glass S- PRG = Surface reaction type

131. . Recently single application bonding system that combine the function of self etching primer and bonding agent have been developed. Reactmer ( shofu,japan ) bond is a single application bonding agent ,it’s a glass ionomer based all-in-one filled adhesive based on PRG technology.

132. INDICATIONS Restoration of root caries Non carious cervical lesions Class v cavities Caries deciduous teeth . ADVANTAGES Fluoride release Fluoride recharging Biocompatibility Smooth surface finish & esthetics Excellent bonding Clinical stability

133. Beautifil II is a second generation giomer introduced into market claiming better optical properties than RMGIC. Jyothi KN et al compared and evaluated giomer and RMGIC in class V noncarious cervical lesions in an in vivo study and they found that giomer restorations exhibited superior surface finish and greater color stability when compared to that of RMGIC. They also conclude both mechanical properties of RMGIC and GIOMER are similar. Clinical evaluation of giomer and resin modified glass ionomer cement in class V noncarious Lesions: An in vivo study jyothi et al JCD2011;14(4)

134. Zirconomer defines a new class of restorative glass ionomer that promises the strength and durability of amalgam with the protective benefits of glass ionomer while completely eliminating the hazard of mercury. Its is also called as “ WHITE AMALGAM ”. The inclusion of zirconia fillers in the glass component of Zirconomer reinforces the structural integrity of the restoration and imparts superior mechanical properties for the restoration of posterior load bearing areas where the conventional restorative of choice is amalgam.

135. Combination of outstanding strength, durability and sustained fluoride protection deems it ideal for permanent posterior restoration in patients with high caries incidence as well as cases where strong structural cores and bases are required.

136. Ideal for Restoration of Class I & II cavities Structural base in sandwich restorations All classes of cavities where radiopacity is a prime requirement Core build-up under indirect restorations Root surfaces where overdentures rest Pediatric and Geriatric restorations Long-term temporary replacement for fractured cusps Fractured amalgam restoration Suitable for ART techniques

137. Zirconomer Benefits • Reinforced with special zirconia fillers to match the strength and durability of amalgam. • Sustained high fluoride release for anti- cariogenic benefits especially in cases with high caries risk. • Packable and condensable like amalgam without the hazard of mercury, the risk of corrosion, expansion and thermal conductivity. • High flexural modulus and compressive strength ensures longevity in stress bearing areas.

138. • Chemically bonds to enamel/dentin and has tooth-like co-efficient of thermal expansion resulting in low interfacial stresses and long-lasting restorations. Ceramic fillers impart remarkable radiopacity for accurate follow up and diagnosis • Adequate working time with snap-set reaction • Easy mixing and handling characteristics minimize chair time and enables ease of bulk placement • Excellent resistance to abrasion and erosion

139. These are restoratives which are glass ionomer based but with the strength of amalgam. They also provide F - release, natural adhesion to tooth structure, good compatibility and prevent shrinkage, creep, corrosion or thermal conductivity problems associated with other filling materials They have been found to have exceptional wear characteristics, along with other advantages of GIC

140. According to bahadure et al conducted a study to estimate fluoride release of six different dental restorative materials namely Amalgomer CR, Fuji II, Fuji IX, Beautifil II, Dyract extra, and Coltene Synergy. They concluded Amalgomer CR was found to have significantly highest fluoride releasing capacity among the all experimental dental restorative materials. An estimation of fluoride release from various dental restorative materials at different pH: In vitro study Bahadure , et al JOURNAL OF INDIAN SOCIETY OF PEDODONTICS AND PREVENTIVE DENTISTRY 2012 ;30(2)

141. These are newer bioactive materials developed by incorporating hydroxyapatite within glass ionomer powder. These are mainly being used as bone cements in ora maxillofacial surgery and may have a future role as retrograde filling material. Studies have shown that they have a role in bonding directly to bone and affect its growth and developement HAINOMERS

142. 1. Fluoride charged materials : This is a 2 part material comprising of A restorative part and A charge part The restorative part is used is the usual way. When the first burst of fluoride is expended, the material is given a fluoride charge using the second part New Fluoride Releasing GIC’s 2.Low pH “Smart” Material developed to enable release fluoride when the oral pH is low. Aptly called “Smart” materials, the F release is episodic and not continuous which helps to prolong the therapeutic usefulness of the material.

143. To increase the anticariogenic action of GIC Still under experimental stage. Experiments conducted on cariogenic organisms CHLORHEXIDINE IMPEGRENATED GIC

144. 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. Let us wish GIC all the best for the coming years conclusion

145. 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