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  1. 1. Dental Cements Dr.Mohammad Abdulsamad Prosthodontics department
  2. 2. Outlines Introduction Mechanisms Of bonding Zinc Phosphate cement Zinc Oxide Eugenol Cement Zinc Polycarboxylate Glass Ionomer Cement Resin cements Recent advancements in dental cements Conclusion
  3. 3. “Although dental cements are used only in small quantities, they are perhaps the most important materials in clinical dentistry because of their application as luting cements, Cavity liners, bases, and as restorative materials”
  4. 4. Ideal cement properties Biologically compatible Release of fluoride and other minerals (Ca-PO) Good manipulation properties High strength in compression, tension and shear Strong bond: Chemical and micromechanical interlocking Good fracture Toughness
  5. 5. Mechanisms of Bonding Non Adhesive (mechanical bonding) Micromechanical bonding Chemical bonding (molecular Adhesion)
  6. 6. Non adhesive (mechanical) luting ● It holds the restoration in place by engaging small irregularities on the surfaces of both tooth and restoration.
  7. 7. Micromechanical bonding ● Requires etching on enamel surfaces with a phosphoric acid solution or gel, and with a hydrofluoric acid on ceramics ● on metals, electrolytic etching, chemical etching, air abrading can be used to obtain the microporosity
  8. 8. Chemical bonding (Molecular adhesion) ● Involves chemical bonds between molecules ( ionic, covalent ) ● Because of the low physical properties this bond have, it’s considered an Auxiliary bond to enhance mechanical or micromechanical retention and reduce microleakage.
  9. 9. Timeline of dental cements Zinc Phosphate Zinc oxide eugenol Zinc polycarboxylate Glass Ionomer Resin cement (8th generation) 1902 1964 2010 1950 - 1960 1972
  10. 10. Zinc Phosphate Disadvantages Advantages • Pulpal irritation • Lack of antimicrobial effect • Brittleness • Mixed easily (manipulation is less critical ) • Good physical strength • Relatively cheap •Powder : mainly Zinc Oxide + Magnesium oxide + pigments •Liquid : Phosphoric acid + Water + Aluminum Composition
  11. 11. Zinc Phosphate cement applications The historic zinc phosphate cement has fallen out of use. ● Used to be the standard in permanent fixed cast alloy and porcelain restorations ● liner or base
  12. 12. Zinc Phosphate cementation considerations ● Mixing ratio: 2.5 powder / 3.5 liquid ● Dry field is a must until complete hardening ● A fresh mix is highly acidic 1 – 2 Ph > pulp may need protection > varnish > reduced retention
  13. 13. Zinc Phosphate cementation considerations ● The Reaction is Exothermic = reduced setting time > cold glass slap needed ● Powder is divided to small increments and each increment is mixed slowly and across a wide area = Reduce the acidity ● Excess cement is removed after hardening ● Will irritate the gingiva if left in the sulcus
  14. 14. Advantages Disadvantages • Sedative and non irritating effect on the pulp • High sealing capacity • Antibacterial action Zinc oxide eugenol • Low strength and abrasion resistance • High solubility in oral fluids • Potential allergic reaction Composition • Powder : Zinc oxide • Liquid : Purified eugenol or clove oil + >1% alcohol or acetic acid
  15. 15. Zinc oxide eugenol applications ● provisional cementation of crowns and fixed partial dentures ● as a cavity liner ● for retaining fixed prostheses on implant- supported abutments, which facilitates retrievability of the prostheses ● Mixing ratio: 3.1 Powder / 4.1 liquid
  16. 16. Advantages • Chemical bond to tooth structure • Non irritant effect on the pulp Disadvantages • Critical manipulation • Short working time • Lower compressive strength • Viscous nature (not easy to handle and clean) Zinc poly carboxylate Composition • Powder : zinc oxide + tin or magnesium oxide • Liquid : 40% aqueous solution of polyacrylic acid
  17. 17. Zinc poly carboxylate applications much like zinc phosphate this cement is not widely used anymore. ● Could be used for the cementation of cast alloy and porcelain restorations ● orthodontic bands ● cavity liner and base material ● provisional restorative materials
  18. 18. Zinc poly carboxylate cementation considerations ● Mixing ratio: 1.5 powder / 1.0 liquid ● The tooth is isolated and dry until the complete setting of cement. ● Accurate proportions are important ● Rapid mixing 30 – 40 sec ● The mix is placed on both, tooth and restoration while still glossy ● Excess is removed after complete setting
  19. 19. Advantages • Chemical bonding to the tooth • Easy manipulation • High strength • Fluoride release Disadvantages • Pulp irritation and hypersensitivity • High solubility in oral fluids • Slow setting process • High moisture sensitivity Glass Ionomer cement Composition • Powder : Calcium fluoroaluminosilicate glass (fluoride content 10%- 16%) • Liquid : Aqueous solution of Polyacrylic acid + 5% - 10% tartaric acid
  20. 20. Resin modified glass ionomer cement Resin is added to the conventional GIC with less polyacrylic acid which results in Advantages Faster setting Increased resistance to moisture Bonding to composite materials More Translucency Disadvantages More water absorption and expansion Less fluoride release
  21. 21. Glass ionomer cement applications Recently the RMGI is used more commonly than the conventional GIC to : ● Permanent cementation of metal and porcelain crowns and bridges especially in patients with poor plaque control or an active carious lesions ● Orthodontic bands ● liners and base materials ● Restorative material
  22. 22. Glass ionomer cement applications Conventional GIC Powder and liquid RMGI Capsules of RMGI
  23. 23. Glass ionomer cementation considerations ● Mixing ratio: 1.3 Powder / 1.0 liquid ● Tooth surface should be clean and free from saliva (but not completely dehydrated) ● Moisture = weakening of the cement isolation required ● Crowns margins should be protected by a varnish or a sealant for 24 hours to prevent the cement from absorbing water before the complete setting. ● Excess cement is removed as soon as the seating is complete.
  24. 24. Resin luting cements Resin luting cements composition Cement (composite) - A composite made of resin matrix and an inorganic filler •- (lower filler content and lower viscosity than the restorative composites) Adhesive system 1 - Etchants : most commonly 37% phosphoric acid or ( acidic monomer = etchant + primer) in self etch systems 2 - Primer : monomers in water soluble solvents (acetone, ethanol and water) 3 - bonding agent : unfilled fluid resin
  25. 25. Resin luting cements (Adhesives classifications) Source : E. Sofan et al Classification review of dental adhesive systems: from the IV generation to the universal type Annali di Stomatologia 2017;VIII (1):1-17 Generation Number of steps Surface pre- treatment Components Shear bond strength (MPa) 1st 2 Enamel etch 2 2 2nd 2 Enamel etch 2 5 3rd 3 Dentine conditioning 2 - 3 12 - 15 4th 3 Total etch 3 25 5th 2 Total etch 2 25 6th 1 Self-etch adhesive 2 20 7th 1 Self-etch adhesive 1 25 8th 1 Self-etch adhesive 1 Over 30
  26. 26. Resin luting cements (Adhesives classifications) Source : Catherine Stamatacos, DDS; and James F. Simon, DDS, Med. Cementation of Indirect Restorations: An Overview of Resin Cements. Compendium January 2013 Volume 34, Issue 1 Resin cement Curing method Characteristics Indications Light-Cure • Photo-initiator. Activated by light • Increased working time • Decreased finishing time • Color stability • Esthetic restorations • Metal free restorations • Cementing thin, translucent ceramics Dual-Cure • Chemical and light • Bond strength • Esthetics • Ease of use • Cementing thick opaque ceramic • Metal-free restorations Chemical-Cure • Chemical reaction of two materials mixed (self curing) • Useful in areas where light- curing is difficult • Metal restorations • Endodontic posts • Ceramic restorations that prohibit curing unit from adequately polymarizing the resin cement
  27. 27. Resin luting cements (Adhesives classifications) Source : Catherine Stamatacos, DDS; and James F. Simon, DDS, Med. Cementation of Indirect Restorations: An Overview of Resin Cements. Compendium January 2013 Volume 34, Issue 1 Resin cement Adhesive scheme Characteristics Total-Etch 30-40% phosphoric acid-etch, then adhesive is applied • Excellent cement to tooth bond strength • Reduced microleakage • Long term predictability • Requiers multi-steps application technique Self- Etch Self-etching primer, then mixed cement is applied • Ease of use • Less technique sensitivity • Good bond strength Self- Adhesive "One component" phosphoric acid grafted into resin • Able to bond to untreated tooth surfaces • "Selective etching" can be incorporated for improved bond strength
  28. 28. Advantages • Chemical and micromechanical bonding to tooth • Insoluble in the oral fluids • Higher physical strength Disadvantages • Pulpal sensitivity • Microleakage due to shrinkage • Complicated excess removal especially in subgingival margins • High film thickness • Technique sensitive Resin luting cement
  29. 29. Resin luting cements applications ● most useful in anterior ceramic veneers. ● for all-ceramic prostheses where the esthetic demand is very high. ● For post and core build up and cementation. ● For orthodontic brackets.
  30. 30. Cement properties Film thickness (mm) Setting time (min) Solubility (Wt%) Strength (MPa) Compressive Tensile Mechanism of bonding Biologic effect on pulp (Indirect) Effect on bacteria Zinc Phosphate 25 - 35 5 - 14 0.2 80 - 100 5 - 7 Mechanical Irritant Non Zinc Oxide Eugenol 25 - 35 2 - 10 1.5 2 - 35 1 - 2 Mechanical Sedative Antimicrobial Zinc polycarboxylate 20 - 25 6 - 9 0.06 55 - 85 8 - 12 Mechanical + chemical Non-irritant Non Glass Ionomer Cement 25 - 35 6 - 9 1 90 - 140 6 - 7 Mechanical + chemical Irritant Bacteriostatic * Resin cement < 25 2 - 4 0 - 0.01 70 - 172 30 - 40 Micromechanicl + chemical Irritant Non
  31. 31. Recent advancements in dental cements Nanomodifications of glass ionomer cement powder Nanomodified resin-modified glass ionomer cements 7% arginine addition to The adhesive systems Bioactive glass (BAG) as a filler in adhesive systems Source: Advanced Dental biomaterials (2019)
  32. 32. Recent advancements in dental cements Nanomodifications of glass ionomer cement powder • The addition of Nanosized fluoroaluminosilicate glass : • Decreased the setting time • Improved the mechanical properties of the set GIC • Increase the chemical bond strength between the tooth and GIC
  33. 33. Recent advancements in dental cements Nanomodified resin-modified glass ionomer cements • Less susceptible for fracture and expansion • Better esthetics • But still inferior mechanical properties to resin cements and lower fluoride release to conventional GIC • Studies indicates no significant difference between the survival rates of RMGICs and nano-RMGICs • To date, no statistically significant difference has been observed between the fluoride Release from nano-RMGICs and conventional RMGICs.
  34. 34. Recent advancements in dental cements 7% arginine addition to The adhesive systems • Adding 7% arginine to an adhesive systems retain appropriate physical and mechanical properties. Moreover, it showed controlled release and moderate recharge of arginine over a prolonged period of time. • Arginine was released from the adhesive system at a rate and concentration to exhibit Antibacterial effect
  35. 35. Recent advancements in dental cements Bioactive glass (BAG) as a filler in adhesive systems • Bioactiv glass (BAG) it consists mainly of silicon, calcium, sodium, phosphorous,and oxygen • have been used as dental adhesive to remineralize the tooth surface • Bonds chemically to the tooth • Releases calcium and phosphate ions, which have remineralization effects on the demineralized Tooth • dissolution of BAG in an aqueous environment releases alkali ions, resulting in an increase in pH which gives BAG Antibacterial and acid neutralizing properties • BAG addition in the adhesives has been shown to prevent demineralization of enamel due to the Ca and P ion releasing ability, thereby preventing WSL.
  36. 36. Conclusion Increase the physical and chemical properties Enhance the biological potential Implement antibacterial and remineralizing effects We can say that so far, the advancements in dental cements and adhesives are tremendous, but further research is required to optimize the performance in clinical application fully.
  37. 37. Thank You