Dentin Bonding Agent PDF

# Dentin Bonding Agent - The relatively thin intermediate layer between dentin or enamel and unfilled resin is known as dentin bonding agent. ## Classification ### First generation bonding agent - 1956, Bond strength ~ 2-3MPa - Weak bond strength - Enamel etching was not considered - Bond was u...

# Dentin Bonding Agent - The relatively thin intermediate layer between dentin or enamel and unfilled resin is known as dentin bonding agent. ## Classification ### First generation bonding agent - 1956, Bond strength ~ 2-3MPa - Weak bond strength - Enamel etching was not considered - Bond was unstable in water - The commercially available 1 GDBA was based on NPG-GMA which theoretically bonded to enamel and dentin by chelation with calcium on tooth surface ### Second generation bonding agent - 1978. Bond strength 5-6 MPa. - Adhesion was by means of ionic interaction between negatively charged phosphate groups and positively charged calcium ions in smear layer. - Weak bond strength - Primary bond to smear layer rather than underlying dentin - Failure ### Third generation bonding agent - Focused on removal of smear layer using phosphoric acid. - Components of 3G DBA are etchant, conditioner, primer, adhesive: - *Etchant:* - Etching of both enamel and dentin together was contraindicated - Enamel was etched with 37% phosphoric acid - Dentin was treated with mild acid - conditioner - *Conditioner:* - Weak organic acid (maleic acid), low conc. of strong inorganic acid (phosphoric or nitric acid), ethylenediaminetetraacetic acid - It removes smear layer - Demineralize peritubular, intertubular dentin, thereby exposing collagen fibrils. - Increases dentin permeability 5 to 9 times - *Primer:* - Contains bifunctional hydrophilic monomer dissolved in organic solvent - Solvents displace water from moist collagen network to allow infiltration of monomer through nanospaces of exposed collagen network ### Fourth generation bonding agent - Bond strength 16 MPa - 26 MPa - Adhesive - Unfilled or partially filled resin that penetrate the dentin and form resin tags and provide methacrylate group that bonds with the composite resin. - Though bond strength was improved, their application was very complex and time consuming. - Also focused on total elimination of smear layer and smear plug - Clinical steps were simplified using phosphoric acid to etch both enamel and dentin. (37% phosphoric acid.) - This generation is known as etch and rinse adhesives - Has three components - phosphoric acid etchant, primer, adhesive - 3-step total etch and rinse DBA. - Penetration of primer and bonding resin into intertubular dentin - Formation of Hybrid layer. - Wet bonding is observed here. - Etchant & Primer + Adhesive ### Fifth generation bonding agent - Two step etch and rinse DBA. - Provides primer and adhesive as a single bottle. - Etch and rinse phase was followed by application of primer - adhesive solution. - Adv - simple application procedure - less technique sensitive - increased bond strength - Disadv - multiple layer application - sensitive to overwetting and overdrying ### Sixth generation bonding agent - Contains self-etch primer containing acidic monomer and a separate adhesive system. - Two categories are available - 1) Two step system - self etch primer - in 1 bottle - adhesive - another bottle - 2) Single step system - contains acidic monomer, primer and adhesive resin, all in one bottle. - Adv- Time saving - Simultaneous demineralization and resin penetration - No separate etching, rinsing or drying. - Disadv - incompatibility with chemical curing composites. - contains water which influences polymerization. ### Seventh generation bonding agent - Also called all-in-one adhesives or one-bottle adhesives - Etching + priming + adhesion - all in one step. - Adv- more time efficient application procedure - Simultaneous demineralisation and resin penetration - Disadv- Reduced shelf life - less sealing capacity - incompatible with chemical curing composites ### Eighth generation bonding agent - Nano fillers with particle size of 12 nm. - Inc penetration of resin monomer. - All in one step - High bond strength and long shelf life. | Generation | | |---|---| | 4th | Acid, Primer, Adhesive | | 5th | Acid, Primer, Adhesive | | 6th | Acid, Primer, Adhesive | | 7th | Acid, Primer, Adhesive | | | | |:--:|:--:| | | Etch and Rinse system | | | Self etch system |