Luting cements

luting cements used in dental practice.

1. Presented By :- Krittika Kuhar 1 st year MDS LUTING CEMENTS

2. CONTENTS INTRODUCTION IDEAL REQUIREMENTS OF LUTING CEMENTS CLASSIFICATION CEMENTS USED FOR LUTING -- Zinc Phosphate Cement -- Zinc Polycarboxylate Cement -- Zinc Oxide Eugenol -- Glass Ionomer Cement -- Resin Luting Agent CONCLUSION REFERENCES

3. INTRODUCTION Numerous dental treatments necessiate attachment of indirect restoration and appliances to the teeth by means of a cement. The long- term clinical outcome of fixed prosthodontic treatment depends on the use of adhesives that can provide an impervious seal between the restoration and the tooth .

4. Definitions Cement  Substance that hardens to act as base , liner , filling material , or adhesive to bind devices or prosthesis to tooth structure or to each other. ( Anusavice 11 th Edition) Cementation  Attaching a restoration to natural teeth by means of a cement . (GPT-9) Luting Agent  any material used to attach or cement indirect restorations to prepared teeth. (GPT-9 )

5. Requirements of luting cement Adhesion to restorative material Adequate strength to resist functional forces Lack of solubility in oral tissues Low film thickness Biocompatibility with oral tissues Radio-opaque Anti-cariogenic properties Relative ease of manipulation Esthetic / color stability An ideal luting cement should have physicomechanical properties resembling those of dentine.

6. cLASSIFICATION ISO classification ( BASED ON INGREDIENTS ) Water-based cements Zinc phosphate, glass ionomer , etc. Oil-based cements ZOE and noneugenol cements Resin or polymer-based cements Resin cements, compomer , etc.

7. Classification of cements based on application (ISO 9917-1:2007)* a. Luting b. Bases or lining c. Restoration

8. BONDING MECHANISM According to Schillinburg , the cement , tooth surface and prostheses interface bonding mechanism can be divided into 3 types :- Non Adhesive ( mechanical ) Micromechanical Molecular

9. Non Adhesive (Mechanical) T he luting agent served primarily to fill the gap and prevent entrance of fluids . It holds the restoration in place by engaging small irregularities on the surfaces of both tooth and restoration E xhibits no adhesion on the molecular level . For eg Zinc Phosphate The nearly parallel opposing walls of a correctly prepared tooth make it impossible to remove the restoration without shearing or crushing the minute projections of cement extending into recesses in the surfaces.

10. The crown can be removed only along the path ( large arrow ) determined by the axial walls of the preparation . Cement extending into small irregularities of the adjoining surfaces {shown magnified in the two large circles) prevents removal along any path more vertical than the sides of the irregularities (small arrows).

11. Micromechanical Bonding The deep irregularities necessary for micromechanical bonding can be produced on enamel surfaces by etching with a phosphoric acid solution or gel21, on ceramics by etching with hydrofluoric acicF ; and on metals by electrolytic etching, chemical etching, sandblasting, or by incorporating salt crystals into the preliminary resin pattern. Resin cements have tensile strengths in the range of 30 to 40 MPa , which is approximately five times that of zinc phosphate cement. When used on pitted surfaces, they can provide effective micromechanical bonding

12. Composite resin cements hold the restoration to the tooth by penetrating into deep and small surface pits.

13. Molecular adhesion Molecular adhesion involves physical forces (bipolar, Van der Waals and chemical bonds (ionic, covalent) between the molecules of two different substances. Newer cements, such as polycarboxylates and glass ionomers , possess some adhesive capabilities, although this is limited by their relatively low cohesive strength . They still depend primarily on nearly parallel walls in the preparation to retain restorations .

14. True adhesion is the molecular attraction exerted between the surface of bodies in contact.

15. ZINC PHOSPHATE CEMENT One of the oldest cements Introduced by Dr Otto Hoffman in 1877

16. APPLICATIONS 1. Luting of restorations (inlays, crowns, fixed dental prostheses, etc.) 2. High strength bases. 3. Temporary restorations. 4. Luting of orthodontic bands and brackets . CLASSIFICATION ISO 9917-1:2007 designates them as a. Luting (Maximum film thickness—25 μm ) b. Bases and lining AVAILABLE AS  . Powder and liquid system. . Capsules of preproportioned powder and liquid.

17. Setting reaction When the powder is mixed with liquid, phosphoric acid attacks the surface of the particles and releases zinc ions . The aluminum in the liquid is essential for cement formation. The aluminum complexes with the phosphoric acid and the zinc ions to form a zinc aluminophosphate gel . The reaction is exothermic .

18. Clinical Manipulation

19. MIXING TIME 1.5-2 min (Philips) WORKING TIME 5 min (Philips) SETTING TIME 5-9 min (CRAIG) 5-14 min (O’BREIN) FILM THICKNESS TYPE 1 <25µm TYPE 2 <40µm FROZEN GLASS TECHNIQUE :- To prolong working time and shorten setting time Glass slab is cooled at 6 to -10 degree C 50-75% more powder incorporation Working time increased by 4-11 min Setting time shortened by 20-40% Due to increased P:L ratio , decreased solubility in oral fluids. SLAKING THE FLUID

20. No chemical adhesion Low tensile strength Post cementation sensitivity ( Resin based sealer / liner decreases casting retentive stress by 42% - Johnson et al , 2004) High solubility in oral fluids 0.2% in 24 h  Marginal leakage . Over 100 years of clinical experience Longetivity . (27 fixed prosthesis that were in clinical service from 2 to 43 years) * High initial strength Adequate compressive strength Low cost Can be used in regions of high masticatory stress or long span prosthesis ADVANTAGES DISADVANTAGES * Margerit J, Cluzel B, Leloup JM, Nurit J, Pauvert B, Terol A (1996 ) Chemical characterization of in vivo aged zinc phosphate dental cements. J Mater Sci Mater Med 7:623–628

21. Ceramic inlay Veneer resin bonded FPD Low retentive preparations • Metallic inlay/ onlay •Metal–ceramic feldspathic full crowns •Metal prefabricated or customized post •Partial fixed prosthesis MOST PREFERRED FOR Implant supported crowns Multiple unit implant supported prostheses INDICATIONS CONTRAINDICATIONS Ladha K, Verma M. Conventional and contemporary luting cements: an overview. The Journal of Indian Prosthodontic Society. 2010 Jun 1;10(2):79-88.

22. MODIFIED ZINC PHOSPHATE CEMENT FLUORIDE CEMENT Add stannous fluoride Higher solubility , lower strength ZINC SILICOPHOSPHATE Zinc Phosphate + Silicate Higher strength , lower solubility Fluoride released , high film thickness 88 µm Transluency

23. COPPER Containing Zinc Phosphate CEMENTS (not widely used) Copper (2-97%) was added to Zinc Phosphate cement , historically Pure Copper Phosphate cement  Teeth discoloration and toxic Not used  High acidity , High solubility and Low strength Indicated : deciduous teeth where it was not possible to remove all caries In cementation of cast silver cap splints-in facial fractures Silver cements contained small percentage of silver phosphate.

24. POLYCARBOXYLATE CEMENT DENNIS SMITH in 1968 FIRST CEMENT WITH ADHESIVE BOND TO TOOTH STRUCTURE ALSO KNOWN AS POLYACRYLATE CEMENT

25. Applications Primarily for luting permanent restorations. As bases and liners. Used in orthodontics for cementation of bands. Also used as root canal fillings in endodontics . Cementing SS crown in Peadiatric Dentistry. AVAILABLE AS . Powder and liquid in bottles . Water settable cements As precapsulated powder/liquid system

26. INGREDIENT FUNCTION Zinc Oxide Basic ingredient Magnesium Oxide Principal modifier , aids in sintering Oxides of Bismuth and Aluminum Small amounts Stannous Fluoride adjust the setting time, increase the strength, and enhance the manipulative properties COMPOSITION OF POWDER Liquid - water solution of polyacrylic acid or a copolymer of acrylic acid with other carboxylic acids, such as itaconic Acid. Molecular weight ranges from 30,000 to 50,000 Acid concentration 32-42%

27. Setting REAction When the powder and liquid are mixed, the surface of powder particles are attacked by the acid, releasing zinc, magnesium and tin ions. These ions bind to the polymer chain via the carboxyl groups . They also react with carboxyl groups of adjacent polyacid chains to form cross-linked salts. Structure of set cement The hardened cement consists of an amorphous gel matrix of zinc polyacrylate in which unreacted powder particles are dispersed.

28. Mechanism of adhesion C hemical bond to tooth structure. The polyacrylic acid bonds to calcium ions on the surface of enamel or dentin via Carboxyl group on the surface of enamel and dentin Bond with Enamel ( 3.4–13.1 Mpa ) > Dentin ( 2.07 MPa ) Weak bond with gold No perceptible bond with porcelain MIXING OF CEMENT P/L ratio is 1.5 by weight Non absorbent mixing surface eg glass slab Liquid dispensed just before the mixing (evaporates quickly) Cement must be used before it loses its glossy appearance indicating free carboxylic acid. No gloss - Cobweb

29. INDICATIONS CONTRADICTIONS Cast Crown PFM crown Patient with previous history of sensitivity. Pressed ceramic crown , ceramic inlay , ceramic veneer Resin bonded FPD Cast post and core Crown or FPD

30. Relatively lower compressive strength Need for clean surface for adhesion Short working time Low Irritation Chemical bond to tooth structure and alloys Easy manipulation Adequate strength Low solubility Adequate film thickness Anticariogenic Advantages Disadvantages

31. ZINC OXIDE EUGENOL Provisional luting cement

32. TYPES Type I zinc oxide eugenol for temporary cementation . Type II zinc oxide eugenol cement for temporary restorations Type II I zinc oxide eugenol —cavity liner (was previously Type IV).

33. INGREDIENT WEIGHT % FUNCTION EUGENOL 85 Reacts with Zinc Oxide OLIVE OIL 15 Plasticizer LIQUID

34. manipulation POWDER: LIQUID- 4:1 TO 6:1 by weight . Measured quantity of powder and liquid is dispensed onto a cool glass slab. Powder is incorporated in liquid Spatulated in circular motion.. It exhibits pseudo-thickening . For temporary restorations a thick putty-like consistency is recommended. TWO PASTE SYSTEM Equal length of each paste are dispersed and mixed until the uniform colour is observed.

35. Advantages Disadvantages ideal pulp compatibility ( obtudent and sedative effect on pulp) good initial adaptation to cavity walls lower solubility in most acids low compressive strength poor resistance to abrasion and disintegration continued loss of eugenol by fluid extraction. As such, pure ZOE is not suitable as a permanent luting agent. Going RE, Mitchem JC. Cements for permanent luting: a summarizing review. The Journal of the American Dental Association. 1975 Jul 1;91(1):107-17.

36. MODIFIED ZINC OXIDE EUGENOL CEMENTS EBA-ALUMINA MODIFIED CEMENTS A part of the liquid is substituted by orthoethoxy benzoic acid (EBA) . Alumina is added to the powder. Rigidity of Alumina is more than that of fused quartz . Reinforcing aluminium oxide by substitution of fused quartz :- Mixing properties and compressive strength improved Film thickness reduced. Tensile strength in same range as Zinc Phosphate ADVANTAGES DISADVANTAGES Palliative to pulp Good initial adaptation Exhibit compressive and tensile strengths in the same ranges as ZnP . Poor resistance to abrasion and disintegration Continual loss of eugenol by leaching Questionable long-range clinical performance.

37. GLASS IONOMER CEMENT Generic name of group of materials that use silicate glass powder and an aqueous solution of polyacrylic acid. Biomimetic Developed in 1970s by Wilson and Kent

38. The GICs are classified below: Type I: Luting crowns, bridges, and orthodontic brackets Type IIa : Esthetic restorative cements Type IIb : Reinforced restorative cements Type III: Lining cements, base

39. Composition POWDER INGREDIENT WEIGHT % SILICA 41.9 ALUMINA 28.6 ALUMINIUM FLURIDE 1.6 CALCIUM FLUORIDE 15.7 SODIUM FLUORIDE 9.3 ALUMINIUM PHOSPHATE 3.8 The powder is an acid-soluble calcium fluoroaluminosilicate glass Lanthanum , strontium, barium or zinc oxide additions provide radiopacity

40. LIQUID COMPONENT FUNCTION Polyacrylic acid in the form of copolymer with itaconic acid, maleic acid and tricarballylic acid Copolymerizing with itaconic , maleic acid, etc. tends to increase reactivity of the liquid, decrease viscosity and reduce tendency for gelation Tartaric acid (5% by mass) Improves the handling characteristics, increases working time and shortens setting time. WATER Water is the most important constituent of the cement liquid, it is the medium of reaction and it hydrates the reaction products. The amount of water in the liquid is critical. Too much water results in a weak cement. Too little water impairs the reaction and subsequent hydration

41. SETTING REACTION

42. MECHANISM OF ADHESION

43. Mixing with a stiff spatula on non absorbant pad. 2 increments. First increment is mixed for 5-10 sec  subequent increment. Total mixing time should not exceed 30-40 sec Glossy finish – residual polyacid for adhesion Dull mix : reduced adhesion. DISCARDED.

44. SETTING TIME- Type 1 - 4 to 5 mins Type 2- 7 mins SURFACE PREPARATION- The tooth should be cleaned for effective adhesion. A pumice slurry is used to remove the smear layer. Conditioning :- with 10% polyacrylic acid or 37% phosphoric acid for 10-20 seconds. Rinse with water for 20 seconds. After rinsing the preparation the surface should be dried but not dessicated and it should remain uncontaminated by saliva or blood.

45. • Initial solubility (1.25% wt ) • Sensitivity to humidity Post-op sensitivity ( Woznaik 1984 ) esp with anhydrous freeze dried polyacid (Simmons 1986) Friendly handling •Fluidity •Adhesion to tooth structure and metals •Fluoride release and uptake •Adequate translucency •Adequate strength (85MPa for luting) •Relative low cost ADVANTAGES DISADVANTAGES

46. I ntraradicular posts •Partial fixed prosthesis in areas of high occlusal load Class 2 and 6 cavities , lack fracture toughness. Metallic crowns •Metal–ceramic crowns •High strength metal-free crowns (alumina and zirconia) INDICATIONS CONTRAINDICATIONS

47. Hybrid Ionomer cement Self cure or light cure ( or resin modified glass ionomers are present for cementation ) Composition The powder contains: Radioopaque fluroaluminosilicate glass Photo-initiators or Chemical initiators or both Polymerizable resin Micro encapsulated potassium persulphate Ascorbic acid as catalyst The Liquid contains : Aqueous solution of Polycarboxylic acid modified with pendant methacrylate group Tartaric acid 2 , hydroxyethyl methacrylate monomers (HEMA)

48. Setting reaction Setting includes both polymerization and acid-base reaction. The initial setting occurs by polymerization of the methacrylate groups giving it a high early strength. Polymerization may be light cured or chemical cured depending on the type of cement. Subsequently the acid-base reaction sets it thereby completing the setting reaction and giving the cement its final strength. Working time >2.5 min Setting time about - 5 min from placement (depends on brand)

49. Mechanism of retention Several RMGI systems (e.g. RelyXTM Luting Cement and RelyXTM Luting Plus Cement, 3M ESPE) do not require any etching, priming or conditioning of the tooth and thus can be considered as self-adhesive cements . Others, such as AdvanceTM (Caulk/ Dentsply ) and FujiTM CEM or FujiTM Plus (GC Dental), suggest the use of additional conditioning agents. Adhesion is a combination of 2 factors :- the modification of the dentinal smear layer and interpenetration of the dentinal tubules by the fluid cement followed by polymerization and entanglement with collagen fibers ; • ionic reaction of the polycarboxylate with the calcium ions of hydroxyapatite

50. application Restoration of Class I, III or V cavities. Bases and liners. As adhesives for orthodontic brackets. Cementation of crowns and FDPs. Repair of damaged amalgam cores or cusps. Retrograde root filling. ( Uses vary according to brand .)

51. Less biocompatible compared to GIC Hygroscopic expansion (HEMA) High solubility (4 times in lactic acid as GIC) CONTRAINDICATIONS Metal-free ceramic restorations, susceptible to erosion • Intraradicular post Fluoride release similar to GIC •Improved compressive and diametral strength INDICATIONS Metallic restorations • Metal–ceramic , FPD , GIC core build up , amalgam , composites ADVANTAGES DISADVANTAGES

52. The term Compomer is derived from composite and GIC Fluoride releasing ability of conventional GIC and durability of composite. COMPOMER

53. COMPOSITION Compomers for luting purposes are available as a two component system, either powder/liquid or as two pastes Powder : strontium aluminofluorosilicate , metallic oxides, chemical-activated and/or light-activated initiators. Liquid : polymerizable methacrylate/carboxylic acid monomers , multifunctional acrylate monomers, water

54. PROPERTIES Tensile strength , flexural strength and wear resistance of compomer is superior. Glass ionomer cement but less effective than resin composites. Cementation of metal prostheses Hygroscopic expansion – all ceramic veneers (C/I)

55. RESIN CEMENTS Low viscosity composite materials with filler distribution and initiator content adjusted to allow for a low film thickness and suitable working and setting time. ISO specification 4049 (2009) classifies resin cement as :- CLASS 1 – Self Cured CLASS 2 – Light cured CLASS 3 – Dual Cured (most commercially used)

56. COMPOSITION High molecular weight molecules like Bis -GMA , UDMA and Bis -EMA are combined with smaller molecules DEGDMA , TEGDMA  High conversion and low volumetric shrinkage . Filler (30-66%) contains silanted radiopaque glasses such as barium , strontium , zirconia with silica particles . Avg filler size 0.5-8 micrometers . Camphorquinone and tertiary amine – Initiate light activated reaction Self cure activator – Benzoyl peroxide

57. Manipulation use of dental bonding agents is essential to obtain adequate bond strength of the cement to the tooth structure . the use of an etchant , e.g. 37 % phosphoric acid gel moisture control is critical . surface of the prosthetic device also has to be prepared by sand-blasting or chemical treatments, e.g. with a silane primer . Working time is 2–4 min while set time is 5–10 min It is very important to clean up the cement within the window of time specified by the manufacturer, otherwise the cement sets very hard and the excess is extremely difficult to remove.

58. PROPERTIES Compressive strength : 180 MPa (26000 Psi) Tensile strength : 30 MPa (4000 Psi) Film thickness : 10–25 μ m Biological properties : Irritating to the pulp. Pulp protection with calcium hydroxide or GIC liner is necessary for areas close to the pulp. Solubility : Insoluble in oral fluids . Polymerization shrinkage : Is high Adhesion properties : They do not adhere to tooth structure , which may lead to microleakage if used without etching and bonding. Bond strength to enamel : 7.4 MPa (1070 Psi ). Bond strength to enamel is usually strong. Failure most often occurs at the metal-resin interphase .

59. SELF ADHESIVE RESIN CEMENTS Combining advantages of GIC ( adhesion and fluoride release) with mechanical properties of Resin cements. Presented as 2 paste or powder and liquid.

60. indications Cementation of cast Single alloy restoration and bridges Ceramic metal crown and bridges Ceramic (except veneers) Indirect Composite restoration Prefabricated posts High Strength Ceramics

61. Properties Higher cytotoxicity than resin cements and acid-base cements Flexural strength – 50-100 Mpa Compressive strength – 200-240Mpa Film thickness – 15 and 20 micrometer Bonding mechanism with tooth :- Micromechanical Interlocking and chemical Interaction between acidic groups and hydroxyapatite Fluoride content is low (10%) and its beneficial effects have not been clinically proven.

62. conclusion No single luting agent is ideal in all the clinical situations. Several new materials are available differing each other in content and physical attributions. Therefore it may be difficult to the dentist to make a choice amongst so many alternative products. Each luting agent has different physical, mechanical and biological characteristics resulting from its chemical structure. So, to achieve a clinical success, the clinician should be aware of the qualities, advantages and disadvantages of each type of cement.

63. References Anusavice KJ,  Phillip’s Science of Dental Materials , WB Saunders Co., Philadelphia, 2003, 11 th  Edition, 443-493 . Sakaguchi RL, Powers JM,  Craig’s Restorative Dental Materials , Elsevier, Mosby, Philadelphia, 2011, 12 th  Edition, 327-348 . Herbert T. Schillinberg – Fundamentals of Fixed Prosthodontics – 3 rd Edition Going RE, Mitchem JC. Cements for permanent luting: a summarizing review. The Journal of the American Dental Association. 1975 Jul 1;91(1):107-17 . Ladha K, Verma M. Conventional and contemporary luting cements: an overview. The Journal of Indian Prosthodontic Society. 2010 Jun 1;10(2):79-88.

64. Petrich A, VanDercreek CJ, Kenny CK. Dental luting cements. Clinical Update (National Naval Dental Center). 2004 Mar;26:31-2 . Going RE, Mitchem JC. Cements for permanent luting: a summarizing review. The Journal of the American Dental Association. 1975 Jul 1;91(1):107-17 Margerit J, Cluzel B, Leloup JM, Nurit J, Pauvert B, Terol A (1996) Chemical characterization of in vivo aged zinc phosphate dental cements. J Mater Sci Mater Med 7:623–628 Mitra SB. Dental cements: formulations and handling techniques. InDental Biomaterials 2008 Jan 1 (pp. 162-193). Woodhead Publishing.