Bonding Systems 1

DLA 1201, exam 5

1. Bonding Systems, Modes of Cure, Oxygen-Inhibited Layer Chapter 5 1

2. Bonding Systems History of the development of bonding systems First generation: 1970s Second generation: Early 1980s Third generation: Late 1980s Fourth and fifth generation: Early 1990s Total etch Sixth generation: Late 1990s Self-etching systems Seventh generation: Early 2000s Eighth generation: Not on market Each generation has consisted of better materials or simpler procedures 2

3. Bonding Systems The first generation bonding agents are those dentists used in the 1970s. The dentist would etch the enamel with acid and place a self-cured, unfilled bonding resin on the enamel only. 3

4. Bonding Systems By the late 1970s and early 1980s, both enamel and dentin bonding agents ( second generation ) were being used, and they were light-cured. The dentin still was not etched. This only allowed bonding to the smear layer of the dentin and resulted in a weak bond. 4

5. Bonding Systems In third generation bonding systems, the dentin was etched but not for a long enough period and then it was dried. So , bonding resin did not penetrate the dentin surface correctly. 5

6. Bonding Generations 6

7. Bonding Systems In the early 1990s, etching both enamel and dentin with phosphoric acid (called total etch ) was an accepted technique. Not only was the smear layer removed, but the surface of the dentin was etched and kept moist, allowing for the penetration of the hydrophilic resin primers into etched dentin surfaces. 7

8. Total Etch Systems The bond strength to dentin increased to about 20-30 MPa . The “wet” dentin bonding technique was introduced in the United States by Jon Kanca . Primer and bonding resins were applied separately Two bottles (4 th gen) Primer and bonding resins together One bottle (5 th gen) 8

9. Fourth and Fifth Generation Bonding Systems Total-etch (AKA all-etch or etch-and-rinse) refers to phosphoric acid etching of both enamel and dentin with a separate step that includes rinsing off the acid and lightly drying the tooth to leave the dentin moist. Dentin is composed of approximately 70% mineral and 30% collagen and water. When the mineral is removed from the surface of the dentin by the acid etchant, collagen fibrils are exposed and the remaining mineral is roughened on its surface When the acid is rinsed, the dentin is left slightly moist (glistening but no water puddles), so that the collagen fibrils stay fluffed up. 9

10. Fourth and Fifth Generation Bonding Systems The total-etch technique became successful when hydrophilic (water-loving) resin monomers (2 hydroxymethyl methacrylate, or HEMA) were added to the primer and adhesive The hydrophilic monomer facilitated the penetration of the adhesive resin into the moist dentinal tubules and peritubular dentin. When dentin bonding resins are applied to moist dentin, the solvents in which the resins are dissolved allow the resins to penetrate through the water and around the fluffed-up collagen fibrils, into the dentinal tubules and etched dentin surface. Drying with are is done at this stage to remove the volatile solvents from the resin and any remaining water. The resin is then light-cured 10

11. Hydrophilic monomer= primer Hydrophobic adhesive= bond 11

12. Fourth and Fifth Generation Bonding Systems The layer that is formed by the intermixing of dentin bonding resin with collagen fibrils and the etched dentin surface is called the hybrid layer . Because of its combination (or hybrid) of dentin components and resin The resin rich hybrid layer facilitates bonding of the composite resin to the tooth through a chemical resin-to-resin bond 12

13. Fourth Generation Two-bottle adhesive system Three basic steps Acid etch (rinse) Application of primer (dry) Application of bonding resin (cured) Two-bottle total etch systems provide the strongest bonds to dentin of all the bonding systems, assuming the technique is followed carefully. If over-etching, under-etching, over-drying, under-drying of the dentin occurs, the bond strength can be diminished. 13

14. Fourth Generation two-bottle 14 Fourth Generation: 2 Bottles (3 steps) Step 1: Etch, Rinse, and gently air dry. Leave dentin moist Step 2: Apply primer (A) gently air dry Step 3: Apply bonding resin, gently air dry, light cure Strongest, most reliable bonds to enamel and dentin Reliably etches enamel Brands: Scotchbond , Multi-Purpose, ALL BOND Bond-It DenTASTIC All-purpose Gluma Solid Bond OptiBOND ProBOND Syntac

15. Bonding Systems The fifth generation is a one bottle system where the primer and bonding resins are combined. Etch is separate step Many bonding systems have a chemical activator that can be mixed 15

16. Fifth Generation One Bottle Fifth Generation: 1 Bottle (2 steps) Step 1: Etch, rinse, gently air dry. Leave dentin moist Step 2: Apply primer and bonding resin, gently air dry, light cure Strong bonds to enamel and dentin Reliably etches to enamel Brands: ONE-STEP PLUS Adper Bond-1 DenTASTIC ExciTE Gluma Comfort Bond OptiBond Solo Plus PQ1 Prime & Bond NT 16

17. Self-Etch Bonding Systems Generation 6 and 7 These systems have been developed to not require the use of phosphoric acid etching and the rinsing and partial drying steps. One- and two-bottle systems incorporate acidic groups (typically carboxylic acid) in the bonding agent that will etch eneamel and dentin and allow penetration of the resin with out the need for rinsing and drying. These are called self-etching bonding systems 17

18. Self- Etch Bonding Systems 6 th and 7 th gen https :// www.youtube.com/watch?v=lc0X5uWW8dg&feature=player_detailpage The primers use water as a solvent to ionize the acidic monomer. Etching of the dentin with acidic primers dissolves the smear layer without deeply demineralizing the dentin and opening the tubules. Etching is not as deep as with total etch systems The acid component gradually shifts in pH to neutral and is incorporated in to the polymerized resin, as are the tooth mineral and smear layer 18

19. Self- Etch Bonding Systems 6th and 7th gen When the solvent has evaporated, the adhesive layer is thin and not very strong. Applying two coats of adhesive resin can increase the bond strength While total-etch systems have the highest bond strengths, self-etch systems have less postoperative sensitivity because they directly seal the dentin without rinsing and drying steps. Because self-etch systems use acidic primers to demineralize dentin and there is no rinsing, it is easier for the primer and adhesive resin to penetrate the full depth of demineralization. With total-etch systems, the phosphoric acid may be left on too long and the primer cannot penetrate the more deeply etched surfaces, or if the etched surface is dried to much the collagen will collapse and prevent primer and adhesive penetration. The unsealed dentin can contribute to post-operative sensitivity 19

20. Self- Etch Bonding Systems 6th and 7th gen To ensure a good bond to uncut enamel, some manufacturers recommend “selective etching” meaning that enamel only shoul dbe etched with phosphoric acid before the application of the self-etching bonding materials. If dentin is also etched with phosphoric acid, and then a self-etching bonding system is used, a good seal with the dentin may not occur. The phosphoric acid will etch dentin deeper than the primer and bonding resin from the self-etch system can penetrate. 20

21. 6 th Generation Bonding System Two-bottle, self-etch bonding system Two different methods, depending on how they were manufactured Type 1 self-etch: an acidic water-soluble primer is applied first, and hen covered with a light-cured adhesive resin that contains Nanosized filler particles. Example of type 1: Clearfil liner Bond Type 2 self etch: a drop of acidic primer from one bottle is mixed with one drop of adhesive resin from the othe rbottle , and applied to the prepared tooth Example of type 2: ALL-BOND SE So you either mix equal amounts, then apply, or apply in two layers then cure 21

22. 6 th Gen Sixth Generation: 2 Bottles or Chambers (2 steps) Step 1: etch and apply acidic monomer (primer), lightly air dry Step 2: apply bonding resin, gently air dry, light cure Strong bonds to dentin Bonds to enamel are not strong, especially uncut enamel. “selective etch” advisable Brands: AdheSE Adper Primpt L-pop ALL-BOND Brush&Bond 22

23. 7 th Generation Bonding Systems One bottle, “all-in-one” In the early 2000s, the seventh generation systems were self-etching materials, which were improved so that adhesive resin and acidic primer are contained in one bottle, and does not require mixing. Many 7 th gen one-bottle bonding systems require refrigeration to prevent the bonding agent from degrading. https:// www.youtube.com/watch?feature=player_detailpage&v=s4U4dVbT0wY 23

24. 7 th Gen Seventh Generation: 1 Bottle (1 Step) Step 1: Etch, prime, and bond (all in one bottle), gently air dry, light cure Strong bonds to dentin Only a few products reliably etch enamel “Selective Etch” advisable Brands: AdheSE One Adper Easy Bond Clearfil S3 Bond Plus Futurabond DS G-Bond iBond OptiBond All-in-One 24

25. 8 th Generation Bonding Systems The eighth generation is most recent. It is anticipated to be a more universal bonding system that is compatible with all light, self, and dual-cured resins. Universal adhesives will bond not only to tooth but to all dental restorative materials https:// www.youtube.com/watch?feature=player_detailpage&v=8wh5knE398Q 25

26. Clinical Tip To achieve a better seal of the dentin, the adhesives should be scrubbed on the dentin rather than just passively placed on the surface. 26

27. Three Main Steps of Bonding Systems All bonding systems have three main steps in common. Etching with either phosphoric acid or an acid primer Priming with hydro philic monomers in a solvent that penetrates etched surfaces Bonding with hydro phobic bonding resins to seal etched surfaces and to chemically bond to composite resin or resin luting cements 27

28. Modes of Cure Three modes of curing are used for resin bonding agents: Light-cure process Uses a light in the blue wave range to activate a chemical (photosensitizer, camphorquinone ) that reacts with an initiator (tertiary amine) to set off the polymerization reaction. Self-cure process Chemical reaction occurs when two resins are mixed together, one of with contains benzoyl peroxide as an initiator Dual-cure process Uses a combination of self-cure and light-cure ingredients. Dual cure resins can be activated by light or can cure chemically without the application of the light The selection of a resin bonding agent and its mode of cure is dependent on the type of restorative materials being used. 28

29. Oxygen-Inhibited Layer On the surface of the polymerized bonding resin is a very thing coating of uncured resin. The resins used for composites and sealants will also form this layer on their surfaces Polymerization is inhibited where the surface is exposed to air (this layer is called the oxygen-inhibited layer) Once the composite is placed over the bonding resin, its presence will exclude air, and that uncured layer on the bonding resin will cure when the composite is cured. The uncured layer will actually help facilitate a chemical bond between the bonding resin and the composite resin 29

30. Biocompatibility Components of the bonding systems can irritate the skin, mucosa, and eyes. Acidic components can cause burns. Some dental personnel develop allergies to the materials, especially HEMA. PPE should be used when handling these materials. Use of a rubber dam will minimize contact with the patient’s oral mucosa. Any area of contact with the skin should be washed with soap and water An eyewash station should be available to treat accidental exposure to the eyes. Most of the undesirable effects are the result of contact with the unpolymerized components. Once the materials are polymerized the risks of problematic reactions are much lest 30