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  1. 1. Enamel & Dentin Adhesives
  2. 2. Introduction  Advent of composite resin has shifed us to the age of adhesive dentistry  Adhesives have modified cavity preparation concept from “ extension for prevention” to “restriction with conviction” with the invention of acid etching with 85% phosphoric acid in 1955 by Bunocore.
  3. 3. Adhesion  Refers to micromechanical coupling of restoration to tooth structure  Dental adhesive system consists of a conditioner ,primer and bonding agent
  4. 4. hydrophobic hydrophilic compdentin Dentin bonding agent
  5. 5. Ideal Bonding Agent  Eliminates post-operative sensitivity  Thin film thickness  No marginal discoloration  Ease of use  Reasonable shelf life  Bond strength  Moderate cost (Christenseen 2005)
  6. 6. Generations of Adhesives  8 generations :  1st & 2nd without etching  3rd acid etch,separate primer margin staining  4th hybrid layer, concept of wet bonding  5th primer and adhesive in 1 bottle  6th self –etchprimers,decreased sensitivity,bond strength lower than 5th  7th All in one  8th self-etch self-adhere flowable composite (Optibond [Kerr]
  7. 7. New Classification  Etch and Rinse system  Self –Etch - Two bottles applied separately - Two bottles mixed as one solution - All -in-one
  8. 8. Interaction With Dental Hard Tissues  With Enamel  With Dentin  Quality of dentin bonds thought to be determined by the depth of demineralization and extent of the diffusion and impregnation of the monomer (Tay FR et al 2001)  This zone of exposed collagen may be unstable and subjected to hydrolysis (Sano H et al)
  9. 9. - To avoid this ,self etching systems that donot require smear layer removal these latest adhesives based on simplification and application time (Oper Dent 2003)
  10. 10. Smear layer 0.5-5Um
  11. 11. Self-Etching Scheme
  12. 12. Single bottle two-step total etch (wet bonding technique) -Acid etching to remove smear layer - Application of primed adhesive
  13. 13. Total etch
  14. 14. Mode of Demineralization and Hybridization
  15. 15. Adhesion depends upon  Surface area  High surface energy  Wettability
  16. 16. Nano Interaction Zone  Verse hybrid layer  G Bond a type of the 7th generation
  17. 17. Ion Exchange Layer
  18. 18. • Although the smear layer thickness had no effect on resin-dentin bond strength, thick smear layers adversely affected the mean gap width,The etch-and-rinse adhesive systems showed higher microBS and lower mean gap widths (Kenshima et al 2005) • the one-step, low pH, acetone-based self- etching adhesive promoted the higher bond strength values, which were statistically similar to those obtained with the two-step, water-based self-etching adhesive (Pegado et al 2010)
  19. 19. Glass Ionomer Adhesives  Based on resin-modified GIC  Conditioner polyalkanoic acid hybrid layer 0.5um  The shear bond strength of the glass-ionomer adhesive to dentin proved to be independent of the smear layer thickness (El Askary et al 2008)
  20. 20.  Newer generations of adhesives appear to be more tolerant of saliva contamination (Dunn 2004)  Shear bond str. & numbers of gap-free restorations increased significantly with drying time (Jacobsen et al 2006)  Following a correct application procedure, the etch-and-rinse, self-etch and self- adhesive luting agents are equally effective in bonding to enamel and dentin (Van Merbeek 2007)
  21. 21.  Wettability is similar between self-etching and total-etch adhesives.The smear layer affects slightly the wettability of self-etching adhesives (Rosales et al 2008)  Enamel bonding was generally more effective with phosphoric-acid etching. Enamel bonding performance of 2-step self-etching adhesives was improved when phosphoric acid was applied on enamel selectively (Frankenberger et al 2008)
  22. 22. Bond Strength
  23. 23. Thank You